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• WOL for Asus M5A97 built in Realtek Network Adapter

  - by madphp

  I cant get wake on lan to work for my built in network adapter. Its a ASUS M5A97 motherboard, and the network adapter is a Realtek PCIe GBE. I have Shutdown WakeOnLan - Enabled Wake on Magic Packet - Enabled Wake on Pattern Match - Enabled WOL & Shutdown Link Speed - 10 Mbps First I have set up a magic packet client to listen, and the packet is getting through. I have also checked these in Power Management for the network adapter. Allow the computer to turn off this device to save power Allow this device to wake the computer Allow a magic packet to wake the computer.

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• Can't join OS X Mavericks to AD Domain

  - by watkipet

  I'm attempting to join an OS X Mavericks (10.9) client to a Windows Server 2008 Active Directory domain, however the bind fails with this error in the OS X client's system.log: Oct 24 15:03:15 host.domain.com com.apple.preferences.users.remoteservice[5547]: -[ODCAddServerSheetController handleOtherActionError: gotError: Error Domain=com.apple.OpenDirectory Code=5202 "Authentication server encountered an error while attempting the requested operation." UserInfo=0x7f9e6cb3e180 {NSLocalizedDescription=Authentication server encountered an error while attempting the requested operation., NSLocalizedFailureReason=Authentication server encountered an error while attempting the requested operation.}, Authentication server encountered an error while attempting the requested operation. I've joined (bound) Ubuntu Linux clients to the same domain with net ads join in the past with no problems (using the same administrative user). I don't have access to any server logs. Here's the GUI error (from Directory Utility) on the OS X client: Here's the GUI error (from User's and Groups) in System Preferences on the OS X client: Update After some Wiresharking I've got some more info: OS X Client - KDC (over UDP): AS_REQ (no padata) OS X Client <- KDC (over UDP): KRB5KDC_ERR_PREAUTH_REQUIRED OS X Client - KDC (over UDP): AS_REQ (this time with PA-ENC-TIMESTAMP in padata) OS X Client <- KDC (over UDP): KRB5KDC_ERR_RESPONSE_TOO_BIG OS X Client - KDC (over TCP): AS_REQ (also with PA-ENC-TIMESTAMP in padata) OS X Client <- KDC (over TCP): KDC_ERR_ETYPE_NOSUPP ...and that's it. This is what I think is going on: The OS X client sends a kerberos request. The KDC says, "You need to pre-authenticate. Try again" The OS X client tries to pre-authenticate (all this so far is over UDP) Something gets lost on our network and the KDC says, "Oops something went wrong" The OS X client switches to TCP and tries again. Over TCP, the KDC says, "You're using an encryption type I don't support" Note that in its padata records, the OS X client is always using "aes256-cts-hmac-sha1-96" as its encryption type. However, in its KDC_REQ_BODY record it lists the aes256-cts-hmac-sha1-96, aes128-cts-hmac-sha1-96, des3-cbc-sha1, and rc4-hmac encryption types. When the KDC comes back with KDC_ERR_ETYPE_NOSUPP, it uses rc4-hmac as its encryption type in its padata record. I know next to nothing about Kerberos, but it seems to me that the OS X client should go ahead and try the rc4-hmac encryption type. However, it does nothing after this. Update 2 Here's the debug log from Directory Services on the OS X client. Sorry--it's long. 2013-10-25 14:19:13.219128 PDT - 10544.20463 - ODNodeCustomCall request, NodeID: 52A65FAE-4B24-455D-86EC-2199A780D234, Code: 80 2013-10-25 14:19:13.220409 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - client requested OU - 'CN=Computers,DC=domain,DC=com' 2013-10-25 14:19:13.220427 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - Binding using '[email protected]' for kerberos ID 2013-10-25 14:19:13.220571 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - new kerberos credential cache 'MEMORY:0x7fa713635470' for '[email protected]' 2013-10-25 14:19:13.220623 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: loop 1 2013-10-25 14:19:13.220639 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - KDC send 0 patypes 2013-10-25 14:19:13.220653 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - fast disabled, not doing any fast wrapping 2013-10-25 14:19:13.220699 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - Trying to find service kdc for realm DOMAIN.COM flags 0 2013-10-25 14:19:13.221275 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - submissing new requests to new host 2013-10-25 14:19:13.221326 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - connecting to host: udp 192.168.0.1:kerberos (192.168.0.1) tid: 00000001 2013-10-25 14:19:13.221373 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - writing packet: udp 192.168.0.1:kerberos (192.168.0.1) tid: 00000001 2013-10-25 14:19:13.222588 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - reading packet: udp 192.168.0.1:kerberos (192.168.0.1) tid: 00000001 2013-10-25 14:19:13.222617 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - host completed: udp 192.168.0.1:kerberos (192.168.0.1) tid: 00000001 2013-10-25 14:19:13.222665 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_sendto_context DOMAIN.COM done: 0 hosts 1 packets 1 wc: 0.001960 nr: 0.000000 kh: 0.000560 tid: 00000001 2013-10-25 14:19:13.222705 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: loop 2 2013-10-25 14:19:13.222737 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: processing input 2013-10-25 14:19:13.222752 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: got an KRB-ERROR from KDC 2013-10-25 14:19:13.222775 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: KRB-ERROR -1765328359/Additional pre-authentication required 2013-10-25 14:19:13.222791 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - KDC send 4 patypes 2013-10-25 14:19:13.222800 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - KDC send PA-DATA type: 19 2013-10-25 14:19:13.222808 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - KDC send PA-DATA type: 2 2013-10-25 14:19:13.222816 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - KDC send PA-DATA type: 16 2013-10-25 14:19:13.222825 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - KDC send PA-DATA type: 15 2013-10-25 14:19:13.222840 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: using ENC-TS with enctype 18 2013-10-25 14:19:13.222850 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: using default_s2k_func 2013-10-25 14:19:13.227443 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - fast disabled, not doing any fast wrapping 2013-10-25 14:19:13.227502 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - Trying to find service kdc for realm DOMAIN.COM flags 0 2013-10-25 14:19:13.228233 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - submissing new requests to new host 2013-10-25 14:19:13.228320 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - connecting to host: udp 192.168.0.1:kerberos (192.168.0.1) tid: 00010001 2013-10-25 14:19:13.228374 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - writing packet: udp 192.168.0.1:kerberos (192.168.0.1) tid: 00010001 2013-10-25 14:19:13.229930 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - reading packet: udp 192.168.0.1:kerberos (192.168.0.1) tid: 00010001 2013-10-25 14:19:13.229957 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - host completed: udp 192.168.0.1:kerberos (192.168.0.1) tid: 00010001 2013-10-25 14:19:13.229975 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_sendto trying over again (reset): 0 2013-10-25 14:19:13.230023 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - Trying to find service kdc for realm DOMAIN.COM flags 2 2013-10-25 14:19:13.230664 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - submissing new requests to new host 2013-10-25 14:19:13.230726 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - connecting to host: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00010002 2013-10-25 14:19:13.230818 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - connecting to 11: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00010002 2013-10-25 14:19:13.231101 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - writing packet: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00010002 2013-10-25 14:19:13.232743 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - reading packet: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00010002 2013-10-25 14:19:13.232777 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - host completed: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00010002 2013-10-25 14:19:13.232798 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_sendto_context DOMAIN.COM done: 0 hosts 2 packets 2 wc: 0.005316 nr: 0.000000 kh: 0.001339 tid: 00010002 2013-10-25 14:19:13.232856 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: loop 3 2013-10-25 14:19:13.232868 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: processing input 2013-10-25 14:19:13.232900 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: using keyproc 2013-10-25 14:19:13.232910 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: using default_s2k_func 2013-10-25 14:19:13.236487 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: extracting ticket 2013-10-25 14:19:13.236557 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_init_creds: wc: 0.015944 2013-10-25 14:19:13.237022 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - Trying to find service kdc for realm DOMAIN.COM flags 2 2013-10-25 14:19:13.237444 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - submissing new requests to new host 2013-10-25 14:19:13.237482 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - connecting to host: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00020001 2013-10-25 14:19:13.237551 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - connecting to 11: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00020001 2013-10-25 14:19:13.237900 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - writing packet: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00020001 2013-10-25 14:19:13.238616 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - reading packet: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00020001 2013-10-25 14:19:13.238645 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - host completed: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00020001 2013-10-25 14:19:13.238674 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_sendto_context DOMAIN.COM done: 0 hosts 1 packets 1 wc: 0.001656 nr: 0.000000 kh: 0.000409 tid: 00020001 2013-10-25 14:19:13.238839 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - Trying to find service kdc for realm DOMAIN.COM flags 2 2013-10-25 14:19:13.239302 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - submissing new requests to new host 2013-10-25 14:19:13.239360 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - connecting to host: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00030001 2013-10-25 14:19:13.239429 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - connecting to 11: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00030001 2013-10-25 14:19:13.239683 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - writing packet: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00030001 2013-10-25 14:19:13.240350 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - reading packet: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00030001 2013-10-25 14:19:13.240387 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - host completed: tcp 192.168.0.1:kerberos (192.168.0.1) tid: 00030001 2013-10-25 14:19:13.240415 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_sendto_context DOMAIN.COM done: 0 hosts 1 packets 1 wc: 0.001578 nr: 0.000000 kh: 0.000445 tid: 00030001 2013-10-25 14:19:13.240514 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - krb5_credential - krb5_get_credentials_with_flags: DOMAIN.COM wc: 0.003615 2013-10-25 14:19:13.240537 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - valid credentials for [email protected] 2013-10-25 14:19:13.240541 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - switching to cache 'MEMORY:0x7fa713635470' 2013-10-25 14:19:13.240545 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - switching GSS to cache 'MEMORY:0x7fa713635470 2013-10-25 14:19:13.240555 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - Bind Step 5 - Bind/Join computer to domain - 'domain.com' 2013-10-25 14:19:13.241345 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - resolving 'server.domain.com' 2013-10-25 14:19:13.241646 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - added socket 12 for host 'server.domain.com:389' address '192.168.0.2' to kqueue list 2013-10-25 14:19:13.241930 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - Setting kerberos server for 'Kerberos:DOMAIN.COM' to 'server.domain.com' 2013-10-25 14:19:13.241962 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - switching to cache 'MEMORY:0x7fa713635470' 2013-10-25 14:19:13.241969 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - switching GSS to cache 'MEMORY:0x7fa713635470 2013-10-25 14:19:13.242231 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - GSSAPI allow Confidentiality 2013-10-25 14:19:13.242234 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - setting realm 'DOMAIN.COM' for node '/Active Directory/domain.com' 2013-10-25 14:19:13.242239 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - GSSAPI allow Integrity (signing) 2013-10-25 14:19:13.242274 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - GSSAPI using hostname 'server.domain.com' 2013-10-25 14:19:13.242282 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - GSSAPI using initiator credential '[email protected]' 2013-10-25 14:19:13.250771 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - Authenticate to LDAP using Kerberos credential - 0 2013-10-25 14:19:13.250784 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - verified connectivity to '192.168.0.2' with socket 12 2013-10-25 14:19:13.251513 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - locating site using domain domain.com using CLDAP 2013-10-25 14:19:13.252145 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - using site of 'DOMAINGROUP' from CLDAP 2013-10-25 14:19:13.253626 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - resolving 'server2.domain.com' 2013-10-25 14:19:13.253933 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - added socket 13 for host 'server2.domain.com:389' address '192.168.0.1' to kqueue list 2013-10-25 14:19:13.254428 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - Setting kerberos server for 'Kerberos:DOMAIN.COM' to 'server2.domain.com' 2013-10-25 14:19:13.254462 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - switching to cache 'MEMORY:0x7fa713635470' 2013-10-25 14:19:13.254468 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - switching GSS to cache 'MEMORY:0x7fa713635470 2013-10-25 14:19:13.254617 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - setting realm 'DOMAIN.COM' for node '/Active Directory/domain.com' 2013-10-25 14:19:13.254661 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - GSSAPI allow Confidentiality 2013-10-25 14:19:13.254670 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - GSSAPI allow Integrity (signing) 2013-10-25 14:19:13.254689 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - GSSAPI using hostname 'server2.domain.com' 2013-10-25 14:19:13.254695 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - GSSAPI using initiator credential '[email protected]' 2013-10-25 14:19:13.262092 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - Authenticate to LDAP using Kerberos credential - 0 2013-10-25 14:19:13.262108 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - verified connectivity to '192.168.0.1' with socket 13 2013-10-25 14:19:13.262982 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - Computer account either already exists or DC is already Read/Write 2013-10-25 14:19:13.264968 PDT - 10544.20463, Node: /Active Directory, Module: ActiveDirectory - Adding record 'cn=spike,CN=Computers,DC=domain,DC=com' in 'domain.com' The failure point seems to be Computer account either already exists or DC is already Read/Write, however, I can search for 'spike' on the Active Directory server using Active Directory Explorer and it's not there. If I do the same search for the Linux and Windows PCs I added previously, I can find them.

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• IP address spoofing using Source Routing

  - by iamrohitbanga

  With IP options we can specify the route we want an IP packet to take while connecting to a server. If we know that a particular server provides some extra functionality based on the IP address can we not utilize this by spoofing an IP packet so that the source IP address is the privileged IP address and one of the hosts on the Source Routing is our own. So if the privileged IP address is x1 and server IP address is x2 and my own IP address is x3. I send a packet from x1 to x2 which is supposed to pass through x3. x1 does not actually send the packet. It is just that x2 thinks the packet came from x1 via x3. Now in response if x2 uses the same routing policy (as a matter of courtesy to x1) then all packets would be received by x3. Will the destination typically use the same IP address sequences as specified in the routing header so that packets coming from the server pass through my IP where I can get the required information? Can we not spoof a TCP connection in the above case? Is this attack used in practice?

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• How is the MTU is 65535 in UDP but ethernet does not allow frame size more than 1500 bytes

  - by nikku

  I am using a fast ethernet of 100 Mbps, whose frame size is less than 1500 bytes (1472 bytes for payload as per my textbook). In that, I was able to send and receive a UDP packet of message size 65507 bytes, which means the packet size was 65507 + 20 (IP Header) + 8 (UDP Header) = 65535. If the frame's payload size itself is maximum of 1472 bytes (as per my textbook), how can the packet size of IP be greater than that which here is 65535? I used sender code as char buffer[100000]; for (int i = 1; i < 100000; i++) { int len = send (socket_id, buffer, i); printf("%d\n", len); } Receiver code as while (len = recv (socket_id, buffer, 100000)) { printf("%d\n". len); } I observed that send returns -1 on i > 65507 and recv prints or receives a packet of maximum of length 65507.

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• What is Allow multicast from Broadband Network?

  - by PeanutsMonkey

  If a wireless modem router has the option Allow multicast from Broadband Network, what does this mean exactly? What risks are there to leaving it enabled and why would you have it enabled? I understand that a broadcast is sending a packet to every device on the network and a multicast is send a packet to a specified set of addresses. A multicast packet can cross routers whereas a broadcast cannot although I don't quite understand how these "set of addresses are specified"

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• VPN with client-to-client direct connectivity?

  - by Johannes Ernst

  When setting up a VPN, clients (say client1 and client2) usually authenticate to a server, and together the three constitute the VPN. When client1 wishes to send a packet to client2, this packet usually gets routed by way of server. Are there products / configuration blueprints for products where it is possible to send packets directly from client1 to client2 without going though server? (if the underlying network topology permits it, e.g. no firewalls in the way) If not, is there a way by which client1 can send a packet to client2 by way of server, without the server being able to snoop on the content of the packet? (E.g. because the packet is encrypted with the public key of client2) I just asked in the OpenVPN forum, and the answer I got was "not with OpenVPN". So my question is: are there other products with which this is possible? Open-source preferred ... One use case: client1 and client2, typically in separate offices, find themselves both at headquarters. Do they still need to talk to each other via the public internet? Links appreciated. Thank you.

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• How is the MTU is 65535 in UDP but ethernet does not allow frame size more than 1500 bytes

  - by nikku

  I am using a fast ethernet of 100 Mbps, whose frame size is less than 1500 bytes (1472 bytes for payload as per my textbook). In that, I was able to send and receive a UDP packet of message size 65507 bytes, which means the packet size was 65507 + 20 (IP Header) + 8 (UDP Header) = 65535. If the frame's payload size itself is maximum of 1472 bytes (as per my textbook), how can the packet size of IP be greater than that which here is 65535? I used sender code as char buffer[100000]; for (int i = 1; i < 100000; i++) { int len = send (socket_id, buffer, i); printf("%d\n", len); } Receiver code as while (len = recv (socket_id, buffer, 100000)) { printf("%d\n". len); } I observed that send returns -1 on i > 65507 and recv prints or receives a packet of maximum of length 65507.

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• iptables rule on INPUT between 2 ethernet cards on the same host

  - by user1495181

  I have 2 eth cards on the same host. Both connected directly with LAN cable. I set eth0 with ip - 192.168.1.2 I set eth1 with ip - 192.168.1.1 I set this rule: iptables -A INPUT -p tcp -j NFQUEUE --queue-num 0 There are no other rules. (I ran iptables -X,-F) I send TCP syn packet ( with c++ program by using raw socket) from 192.168.1.2 to 192.168.1.1 In wireshark i see that the packet received on eth0, but the iptables rule (above) dosnt apply for this packet. when i sent the packet to remote host and apply this rule on the remote host than it work correct. So, i guess that this is due to the fact that both eth cards exists the same host. . I need to create iptables INPUT rule for local eth card (dest and src on the same machine ). I need it for simplify test. Did i guess the problem correct? is there a way to bypass this? Ps - connected them via switch didn't help. the rule wasn't applied. Run on Ubuntu. TCDUMP show the packet: 10:48:42.365002 IP 192.168.1.2.38550 > 192.168.1.1.34298: Flags [S], seq 0, win 5840, length 0 but logging of iptables like this, has nothing: iptables -A INPUT -p tcp -j LOG --log-prefix '*****************' iptables -A OUTPUT -p tcp -j LOG --log-prefix '#################'

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• Can a network interface be configured to have a default gateway for UDP packets?

  - by Vaibhav

  It is quite possible that my question may not make a lot of sense. I apologize, but I am not a networking guy, and that's my excuse. To elaborate, WikiPedia defines "Default Gateway" as a node on a "TCP/IP" network. And the way it works is that if a network interface is sending a packet to an IP address not present on its subnet, it sends it out to the default gateway (which then knows what to do with that packet). Is this true if a UDP packet (datagram) is involved? I mean, if my network interface is sending a UDP packet to an IP address that is not present on its subnet, would it automatically send it to the Default Gateway as well?

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• Using u32 together with extension headers (how to jump over them?)

  - by bortzmeyer

  I'm trying to filter on some parts of the payload, for an IPv6 packet with extension headers (for instance Destination Options). ip6tables works fine with conditions like --proto udp or --dport 109, even when the packet has extension headers. Netfilter clearly knows how to jump over Destination Options to find the UDP header. Now, I would like to use the u32 module to match a byte in the payload (say "I want the third byte of the payload to be 42). If the packet has no extension headers something like --u32 "48&0x0000ff00=0x2800"` (48 = 40 bytes for the IPv6 header + 8 for the UDP header) works fine, If the packet has a Destination Options, it no longer matches. I would like to write a rule that will work whether the packet has Destination Options or not. I do not find a way to tell Netfilter to parse until the UDP header (something that it is able to do, otherwise --dport 109 would not work) then to leave u32 parse the rest. I'm looking for a simple way, otherwise, as BatchyX mentions, I could write a kernel module doing what I want.

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• Reconstruct a file from a TCP stream

  - by Abhishek Chanda

  I have a client and a server and a third box which sees all packets from the server to the client (but not the other way around). Now when the client requests a file from the server (over HTTP), the third box sees the response. I am trying to reconstruct the file there. I am using libpcap to capture TCP datagrams and trying to reconstruct the file there. Here is what I did Listen for packets on an interface Group all packets which have the same ACK number Sort the group based on SEQ number Extract data from each packet and combine them and write to the disk The problem is, the file thus generated is not exactly the same as the original file. Does everything sound correct here? Some more details: I am using C++ The packet data is being stored as std::vector<char> I did change the byte order while reading the ack number and seq number from the packet using ntohl I am not sure if I need to change the byte order for the data as well. I tried to reverse the data from each packet before combining them, even that did not work. Is there something I am missing?

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• Is this proper OO design for C++?

  - by user121917

  I recently took a software processes course and this is my first time attempting OO design on my own. I am trying to follow OO design principles and C++ conventions. I attempted and gave up on MVC for this application, but I am trying to "decouple" my classes such that they can be easily unit-tested and so that I can easily change the GUI library used and/or the target OS. At this time, I have finished designing classes but have not yet started implementing methods. The function of the software is to log all packets sent and received, and display them on the screen (like WireShark, but for one local process only). The software accomplishes this by hooking the send() and recv() functions in winsock32.dll, or some other pair of analogous functions depending on what the intended Target is. The hooks add packets to SendPacketList/RecvPacketList. The GuiLogic class starts a thread which checks for new packets. When new packets are found, it utilizes the PacketFilter class to determine the formatting for the new packet, and then sends it to MainWindow, a native win32 window (with intent to later port to Qt).1 Full size image of UML class diagram Here are my classes in skeleton/header form (this is my actual code): class PacketModel { protected: std::vector<byte> data; int id; public: PacketModel(); PacketModel(byte* data, unsigned int size); PacketModel(int id, byte* data, unsigned int size); int GetLen(); bool IsValid(); //len >= sizeof(opcode_t) opcode_t GetOpcode(); byte* GetData(); //returns &(data[0]) bool GetData(byte* outdata, int maxlen); void SetData(byte* pdata, int len); int GetId(); void SetId(int id); bool ParseData(char* instr); bool StringRepr(char* outstr); byte& operator[] (const int index); }; class SendPacket : public PacketModel { protected: byte* returnAddy; public: byte* GetReturnAddy(); void SetReturnAddy(byte* addy); }; class RecvPacket : public PacketModel { protected: byte* callAddy; public: byte* GetCallAddy(); void SetCallAddy(byte* addy); }; //problem: packets may be added to list at any time by any number of threads //solution: critical section associated with each packet list class Synch { public: void Enter(); void Leave(); }; template<class PacketType> class PacketList { private: static const int MAX_STORED_PACKETS = 1000; public: static const int DEFAULT_SHOWN_PACKETS = 100; private: vector<PacketType> list; Synch synch; //wrapper for critical section public: void AddPacket(PacketType* packet); PacketType* GetPacket(int id); int TotalPackets(); }; class SendPacketList : PacketList<SendPacket> { }; class RecvPacketList : PacketList<RecvPacket> { }; class Target //one socket { bool Send(SendPacket* packet); bool Inject(RecvPacket* packet); bool InitSendHook(SendPacketList* sendList); bool InitRecvHook(RecvPacketList* recvList); }; class FilterModel { private: opcode_t opcode; int colorID; bool bFilter; char name[41]; }; class FilterFile { private: FilterModel filter; public: void Save(); void Load(); FilterModel* GetFilter(opcode_t opcode); }; class PacketFilter { private: FilterFile filters; public: bool IsFiltered(opcode_t opcode); bool GetName(opcode_t opcode, char* namestr); //return false if name does not exist COLORREF GetColor(opcode_t opcode); //return default color if no custom color }; class GuiLogic { private: SendPacketList sendList; RecvPacketList recvList; PacketFilter packetFilter; void GetPacketRepr(PacketModel* packet); void ReadNew(); void AddToWindow(); public: void Refresh(); //called from thread void GetPacketInfo(int id); //called from MainWindow }; I'm looking for a general review of my OO design, use of UML, and use of C++ features. I especially just want to know if I'm doing anything considerably wrong. From what I've read, design review is on-topic for this site (and off-topic for the Code Review site). Any sort of feedback is greatly appreciated. Thanks for reading this.

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• Server-side Input

  - by Thomas

  Currently in my game, the client is nothing but a renderer. When input state is changed, the client sends a packet to the server and moves the player as if it were processing the input, but the server has the final say on the position. This generally works really well, except for one big problem: falling off edges. Basically, if a player is walking towards an edge, say a cliff, and stops right before going off the edge, sometimes a second later, he'll be teleported off of the edge. This is because the "I stopped pressing W" packet is sent after the server processes the information. Here's a lag diagram to help you understand what I mean: http://i.imgur.com/Prr8K.png I could just send a "W Pressed" packet each frame for the server to process, but that would seem to be a bandwidth-costly solution. Any help is appreciated!

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• Sending state diffs (deltas) and unreliable connections

  - by spaceOwl

  We're building a realtime multiplayer game, in which each player is responsible for reporting its state on every iteration of the game loop. The state updates are broadcasted using unreliable UDP. To minimize state data sending, we've come up with a system that will send only deltas (whatever state data that was changed). This method however is flawed, since a lost packet will mean that other players will not receive the delta, making the game behave in an unexpected way. For example: Assume that state is comprised of: { positionX, positionY, health } Frame 1 - positionX changed --> send a packet with positionX only. Frame 2 - health changed // lost ! Frame 3 - positionY changed --> send a packet with positionY only. // Other players don't know about health change. How can one overcome this issue then? sending the entire data is not always feasible.

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• FreeBSD 8.1 unstable network connection

  - by frankcheong

  I have three FreeBSD 8.1 running on three different hardware and therefore consist of different network adapter as well (bce, bge and igb). I found that the network connection is kind of unstable which I have tried to scp some 10MB file and found that I cannot always get the files completed successfully. I have further checked with my network admin and he claim that the problem is being caused by the network driver which cannot support the load whereby he tried to ping using huge packet size (around 15k) and my server will drop packet consistently at a regular interval. I found that this statement may not be valid since the three server is using three different network drive and it would be quite impossible that the same problem is being caused by three different network adapter and thus different network driver. Since then I have tried to tune up the performance by playing around with the /etc/sysctl.conf figures with no luck. kern.ipc.somaxconn=1024 kern.ipc.shmall=3276800 kern.ipc.shmmax=1638400000 # Security net.inet.ip.redirect=0 net.inet.ip.sourceroute=0 net.inet.ip.accept_sourceroute=0 net.inet.icmp.maskrepl=0 net.inet.icmp.log_redirect=0 net.inet.icmp.drop_redirect=1 net.inet.tcp.drop_synfin=1 # Security net.inet.udp.blackhole=1 net.inet.tcp.blackhole=2 # Required by pf net.inet.ip.forwarding=1 #Network Performance Tuning kern.ipc.maxsockbuf=16777216 net.inet.tcp.rfc1323=1 net.inet.tcp.sendbuf_max=16777216 net.inet.tcp.recvbuf_max=16777216 # Setting specifically for 1 or even 10Gbps network net.local.stream.sendspace=262144 net.local.stream.recvspace=262144 net.inet.tcp.local_slowstart_flightsize=10 net.inet.tcp.nolocaltimewait=1 net.inet.tcp.mssdflt=1460 net.inet.tcp.sendbuf_auto=1 net.inet.tcp.sendbuf_inc=16384 net.inet.tcp.recvbuf_auto=1 net.inet.tcp.recvbuf_inc=524288 net.inet.tcp.sendspace=262144 net.inet.tcp.recvspace=262144 net.inet.udp.recvspace=262144 kern.ipc.maxsockbuf=16777216 kern.ipc.nmbclusters=32768 net.inet.tcp.delayed_ack=1 net.inet.tcp.delacktime=100 net.inet.tcp.slowstart_flightsize=179 net.inet.tcp.inflight.enable=1 net.inet.tcp.inflight.min=6144 # Reduce the cache size of slow start connection net.inet.tcp.hostcache.expire=1 Our network admin also claim that they see quite a lot of network up and down from their cisco switch log while I cannot find any up down message inside the dmesg. Have further checked the netstat -s but dont have concrete idea. tcp: 133695291 packets sent 39408539 data packets (3358837321 bytes) 61868 data packets (89472844 bytes) retransmitted 24 data packets unnecessarily retransmitted 0 resends initiated by MTU discovery 50756141 ack-only packets (2148 delayed) 0 URG only packets 0 window probe packets 4372385 window update packets 39781869 control packets 134898031 packets received 72339403 acks (for 3357601899 bytes) 190712 duplicate acks 0 acks for unsent data 59339201 packets (3647021974 bytes) received in-sequence 114 completely duplicate packets (135202 bytes) 27 old duplicate packets 0 packets with some dup. data (0 bytes duped) 42090 out-of-order packets (60817889 bytes) 0 packets (0 bytes) of data after window 0 window probes 3953896 window update packets 64181 packets received after close 0 discarded for bad checksums 0 discarded for bad header offset fields 0 discarded because packet too short 45192 discarded due to memory problems 19945391 connection requests 1323420 connection accepts 0 bad connection attempts 0 listen queue overflows 0 ignored RSTs in the windows 21133581 connections established (including accepts) 21268724 connections closed (including 32737 drops) 207874 connections updated cached RTT on close 207874 connections updated cached RTT variance on close 132439 connections updated cached ssthresh on close 42392 embryonic connections dropped 72339338 segments updated rtt (of 69477829 attempts) 390871 retransmit timeouts 0 connections dropped by rexmit timeout 0 persist timeouts 0 connections dropped by persist timeout 0 Connections (fin_wait_2) dropped because of timeout 13990 keepalive timeouts 2 keepalive probes sent 13988 connections dropped by keepalive 173044 correct ACK header predictions 36947371 correct data packet header predictions 1323420 syncache entries added 0 retransmitted 0 dupsyn 0 dropped 1323420 completed 0 bucket overflow 0 cache overflow 0 reset 0 stale 0 aborted 0 badack 0 unreach 0 zone failures 1323420 cookies sent 0 cookies received 1864 SACK recovery episodes 18005 segment rexmits in SACK recovery episodes 26066896 byte rexmits in SACK recovery episodes 147327 SACK options (SACK blocks) received 87473 SACK options (SACK blocks) sent 0 SACK scoreboard overflow 0 packets with ECN CE bit set 0 packets with ECN ECT(0) bit set 0 packets with ECN ECT(1) bit set 0 successful ECN handshakes 0 times ECN reduced the congestion window udp: 5141258 datagrams received 0 with incomplete header 0 with bad data length field 0 with bad checksum 1 with no checksum 0 dropped due to no socket 129616 broadcast/multicast datagrams undelivered 0 dropped due to full socket buffers 0 not for hashed pcb 5011642 delivered 5016050 datagrams output 0 times multicast source filter matched sctp: 0 input packets 0 datagrams 0 packets that had data 0 input SACK chunks 0 input DATA chunks 0 duplicate DATA chunks 0 input HB chunks 0 HB-ACK chunks 0 input ECNE chunks 0 input AUTH chunks 0 chunks missing AUTH 0 invalid HMAC ids received 0 invalid secret ids received 0 auth failed 0 fast path receives all one chunk 0 fast path multi-part data 0 output packets 0 output SACKs 0 output DATA chunks 0 retransmitted DATA chunks 0 fast retransmitted DATA chunks 0 FR's that happened more than once to same chunk 0 intput HB chunks 0 output ECNE chunks 0 output AUTH chunks 0 ip_output error counter Packet drop statistics: 0 from middle box 0 from end host 0 with data 0 non-data, non-endhost 0 non-endhost, bandwidth rep only 0 not enough for chunk header 0 not enough data to confirm 0 where process_chunk_drop said break 0 failed to find TSN 0 attempt reverse TSN lookup 0 e-host confirms zero-rwnd 0 midbox confirms no space 0 data did not match TSN 0 TSN's marked for Fast Retran Timeouts: 0 iterator timers fired 0 T3 data time outs 0 window probe (T3) timers fired 0 INIT timers fired 0 sack timers fired 0 shutdown timers fired 0 heartbeat timers fired 0 a cookie timeout fired 0 an endpoint changed its cookiesecret 0 PMTU timers fired 0 shutdown ack timers fired 0 shutdown guard timers fired 0 stream reset timers fired 0 early FR timers fired 0 an asconf timer fired 0 auto close timer fired 0 asoc free timers expired 0 inp free timers expired 0 packet shorter than header 0 checksum error 0 no endpoint for port 0 bad v-tag 0 bad SID 0 no memory 0 number of multiple FR in a RTT window 0 RFC813 allowed sending 0 RFC813 does not allow sending 0 times max burst prohibited sending 0 look ahead tells us no memory in interface 0 numbers of window probes sent 0 times an output error to clamp down on next user send 0 times sctp_senderrors were caused from a user 0 number of in data drops due to chunk limit reached 0 number of in data drops due to rwnd limit reached 0 times a ECN reduced the cwnd 0 used express lookup via vtag 0 collision in express lookup 0 times the sender ran dry of user data on primary 0 same for above 0 sacks the slow way 0 window update only sacks sent 0 sends with sinfo_flags !=0 0 unordered sends 0 sends with EOF flag set 0 sends with ABORT flag set 0 times protocol drain called 0 times we did a protocol drain 0 times recv was called with peek 0 cached chunks used 0 cached stream oq's used 0 unread messages abandonded by close 0 send burst avoidance, already max burst inflight to net 0 send cwnd full avoidance, already max burst inflight to net 0 number of map array over-runs via fwd-tsn's ip: 137814085 total packets received 0 bad header checksums 0 with size smaller than minimum 0 with data size < data length 0 with ip length > max ip packet size 0 with header length < data size 0 with data length < header length 0 with bad options 0 with incorrect version number 1200 fragments received 0 fragments dropped (dup or out of space) 0 fragments dropped after timeout 300 packets reassembled ok 137813009 packets for this host 530 packets for unknown/unsupported protocol 0 packets forwarded (0 packets fast forwarded) 61 packets not forwardable 0 packets received for unknown multicast group 0 redirects sent 137234598 packets sent from this host 0 packets sent with fabricated ip header 685307 output packets dropped due to no bufs, etc. 52 output packets discarded due to no route 300 output datagrams fragmented 1200 fragments created 0 datagrams that can't be fragmented 0 tunneling packets that can't find gif 0 datagrams with bad address in header icmp: 0 calls to icmp_error 0 errors not generated in response to an icmp message Output histogram: echo reply: 305 0 messages with bad code fields 0 messages less than the minimum length 0 messages with bad checksum 0 messages with bad length 0 multicast echo requests ignored 0 multicast timestamp requests ignored Input histogram: destination unreachable: 530 echo: 305 305 message responses generated 0 invalid return addresses 0 no return routes ICMP address mask responses are disabled igmp: 0 messages received 0 messages received with too few bytes 0 messages received with wrong TTL 0 messages received with bad checksum 0 V1/V2 membership queries received 0 V3 membership queries received 0 membership queries received with invalid field(s) 0 general queries received 0 group queries received 0 group-source queries received 0 group-source queries dropped 0 membership reports received 0 membership reports received with invalid field(s) 0 membership reports received for groups to which we belong 0 V3 reports received without Router Alert 0 membership reports sent arp: 376748 ARP requests sent 3207 ARP replies sent 245245 ARP requests received 80845 ARP replies received 326090 ARP packets received 267712 total packets dropped due to no ARP entry 108876 ARP entrys timed out 0 Duplicate IPs seen ip6: 2226633 total packets received 0 with size smaller than minimum 0 with data size < data length 0 with bad options 0 with incorrect version number 0 fragments received 0 fragments dropped (dup or out of space) 0 fragments dropped after timeout 0 fragments that exceeded limit 0 packets reassembled ok 2226633 packets for this host 0 packets forwarded 0 packets not forwardable 0 redirects sent 2226633 packets sent from this host 0 packets sent with fabricated ip header 0 output packets dropped due to no bufs, etc. 8 output packets discarded due to no route 0 output datagrams fragmented 0 fragments created 0 datagrams that can't be fragmented 0 packets that violated scope rules 0 multicast packets which we don't join Input histogram: UDP: 2226633 Mbuf statistics: 962679 one mbuf 1263954 one ext mbuf 0 two or more ext mbuf 0 packets whose headers are not continuous 0 tunneling packets that can't find gif 0 packets discarded because of too many headers 0 failures of source address selection Source addresses selection rule applied: icmp6: 0 calls to icmp6_error 0 errors not generated in response to an icmp6 message 0 errors not generated because of rate limitation 0 messages with bad code fields 0 messages < minimum length 0 bad checksums 0 messages with bad length Histogram of error messages to be generated: 0 no route 0 administratively prohibited 0 beyond scope 0 address unreachable 0 port unreachable 0 packet too big 0 time exceed transit 0 time exceed reassembly 0 erroneous header field 0 unrecognized next header 0 unrecognized option 0 redirect 0 unknown 0 message responses generated 0 messages with too many ND options 0 messages with bad ND options 0 bad neighbor solicitation messages 0 bad neighbor advertisement messages 0 bad router solicitation messages 0 bad router advertisement messages 0 bad redirect messages 0 path MTU changes rip6: 0 messages received 0 checksum calculations on inbound 0 messages with bad checksum 0 messages dropped due to no socket 0 multicast messages dropped due to no socket 0 messages dropped due to full socket buffers 0 delivered 0 datagrams output netstat -m 516/5124/5640 mbufs in use (current/cache/total) 512/1634/2146/32768 mbuf clusters in use (current/cache/total/max) 512/1536 mbuf+clusters out of packet secondary zone in use (current/cache) 0/1303/1303/12800 4k (page size) jumbo clusters in use (current/cache/total/max) 0/0/0/6400 9k jumbo clusters in use (current/cache/total/max) 0/0/0/3200 16k jumbo clusters in use (current/cache/total/max) 1153K/9761K/10914K bytes allocated to network (current/cache/total) 0/0/0 requests for mbufs denied (mbufs/clusters/mbuf+clusters) 0/0/0 requests for jumbo clusters denied (4k/9k/16k) 0/8/6656 sfbufs in use (current/peak/max) 0 requests for sfbufs denied 0 requests for sfbufs delayed 0 requests for I/O initiated by sendfile 0 calls to protocol drain routines Anyone got an idea what might be the possible cause?

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• IP address spoofing using Source Routing

  - by iamrohitbanga

  With IP options we can specify the route we want an IP packet to take while connecting to a server. If we know that a particular server provides some extra functionality based on the IP address can we not utilize this by spoofing an IP packet so that the source IP address is the privileged IP address and one of the hosts on the Source Routing is our own. So if the privileged IP address is x1 and server IP address is x2 and my own IP address is x3. I send a packet from x1 to x2 which is supposed to pass through x3. x1 does not actually send the packet. It is just that x2 thinks the packet came from x1 via x3. Now in response if x2 uses the same routing policy (as a matter of courtesy to x1) then all packets would be received by x3. Will the destination typically use the same IP address sequences as specified in the routing header so that packets coming from the server pass through my IP where I can get the required information? Can we not spoof a TCP connection in the above case? Is this attack used in practice?

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• How to save image drawn on a JPanel?

  - by swift

  I have a panel with transparent background which i use to draw an image. now problem here is when i draw anything on panel and save the image as a JPEG file its saving the image with black background but i want it to be saved as same, as i draw on the panel. what should be done for this? plz guide me j Client.java public class Client extends Thread { static DatagramSocket datasocket; static DatagramSocket socket; Point point; Whiteboard board; Virtualboard virtualboard; JLayeredPane layerpane; BufferedImage image; public Client(DatagramSocket datasocket) { Client.datasocket=datasocket; } //This function is responsible to connect to the server public static void connect() { try { socket=new DatagramSocket (9000); //client connection socket port= 9000 datasocket=new DatagramSocket (9005); //client data socket port= 9002 ByteArrayOutputStream baos=new ByteArrayOutputStream(); DataOutputStream dos=new DataOutputStream(baos); //this is to tell server that this is a connection request dos.writeChar('c'); dos.close(); byte[]data=baos.toByteArray(); //Server IP address InetAddress ip=InetAddress.getByName("10.123.97.154"); //create the UDP packet DatagramPacket packet=new DatagramPacket(data, data.length,ip , 8000); socket.send(packet); Client client=new Client(datasocket); client.createFrame(); client.run(); } catch(Exception e) { e.printStackTrace(); } } //This function is to create the JFrame public void createFrame() { JFrame frame=new JFrame("Whiteboard"); frame.setVisible(true); frame.setBackground(Color.black); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(680,501); frame.addWindowListener(new WindowAdapter() { public void windowOpened(WindowEvent e) {} public void windowClosing(WindowEvent e) { close(); } }); layerpane=frame.getLayeredPane(); board= new Whiteboard(datasocket); image = new BufferedImage(590,463, BufferedImage.TYPE_INT_ARGB); board.setBounds(74,2,590,463); board.setImage(image); virtualboard=new Virtualboard(); virtualboard.setImage(image); virtualboard.setBounds(74,2,590,463); layerpane.add(virtualboard,new Integer(2));//Panel where remote user draws layerpane.add(board,new Integer(3)); layerpane.add(board.colourButtons(),new Integer(1)); layerpane.add(board.shapeButtons(),new Integer(0)); //frame.add(paper.addButtons(),BorderLayout.WEST); } /* * This function is overridden from the thread class * This function listens for incoming packets from the server * which contains the points drawn by the other client */ public void run () { while (true) { try { byte[] buffer = new byte[512]; DatagramPacket packet = new DatagramPacket(buffer, buffer.length); datasocket.receive(packet); InputStream in=new ByteArrayInputStream(packet.getData(), packet.getOffset(),packet.getLength()); DataInputStream din=new DataInputStream(in); int x=din.readInt(); int y=din.readInt(); String varname=din.readLine(); String var[]=varname.split("-",4); point=new Point(x,y); virtualboard.addPoint(point, var[0], var[1],var[2],var[3]); } catch (IOException ex) { ex.printStackTrace(); } } } //This function is to broadcast the newly drawn point to the server public void broadcast (Point p,String varname,String shape,String event, String color) { try { ByteArrayOutputStream baos=new ByteArrayOutputStream(); DataOutputStream dos=new DataOutputStream(baos); dos.writeInt(p.x); dos.writeInt(p.y); dos.writeBytes(varname); dos.writeBytes("-"); dos.writeBytes(shape); dos.writeBytes("-"); dos.writeBytes(event); dos.writeBytes("-"); dos.writeBytes(color); dos.close(); byte[]data=baos.toByteArray(); InetAddress ip=InetAddress.getByName("10.123.97.154"); DatagramPacket packet=new DatagramPacket(data, data.length,ip , 8002); datasocket.send(packet); } catch (Exception e) { e.printStackTrace(); } } //This function is to close the client's connection with the server public void close() { try { ByteArrayOutputStream baos=new ByteArrayOutputStream(); DataOutputStream dos=new DataOutputStream(baos); //This is to tell server that this is request to remove the client dos.writeChar('r'); dos.close(); byte[]data=baos.toByteArray(); //Server IP address InetAddress ip=InetAddress.getByName("10.123.97.154"); DatagramPacket packet=new DatagramPacket(data, data.length,ip , 8000); socket.send(packet); System.out.println("closed"); } catch(Exception e) { e.printStackTrace(); } } public static void main(String[] args) throws Exception { connect(); } } Whiteboard.java class Whiteboard extends JPanel implements MouseListener,MouseMotionListener,ActionListener,KeyListener { BufferedImage image; Boolean tooltip=false; int post; String shape; String selectedcolor="black"; Color color=Color.black; //Color color=Color.white; Point start; Point end; Point mp; Point tip; int keycode; String fillshape; Point fillstart=new Point(); Point fillend=new Point(); int noofside; Button r=new Button("rect"); Button rectangle=new Button("rect"); Button line=new Button("line"); Button roundrect=new Button("roundrect"); Button polygon=new Button("poly"); Button text=new Button("text"); JButton save=new JButton("Save"); Button elipse=new Button("elipse"); ImageIcon fillicon=new ImageIcon("images/fill.jpg"); JButton fill=new JButton(fillicon); ImageIcon erasericon=new ImageIcon("images/eraser.gif"); JButton erase=new JButton(erasericon); JButton[] colourbutton=new JButton[28]; String selected; Point label; String key=""; int ex,ey;//eraser DatagramSocket dataSocket; JButton button = new JButton("test"); Client client; Boolean first; int w,h; public Whiteboard(DatagramSocket dataSocket) { try { UIManager.setLookAndFeel( UIManager.getCrossPlatformLookAndFeelClassName()); } catch (Exception e) { e.printStackTrace(); } setLayout(null); setOpaque(false); setBackground(new Color(237,237,237)); this.dataSocket=dataSocket; client=new Client(dataSocket); addKeyListener(this); addMouseListener(this); addMouseMotionListener(this); setBorder(BorderFactory.createLineBorder(Color.black)); } public void paintComponent(Graphics g) { try { super.paintComponent(g); g.drawImage(image, 0, 0, this); Graphics2D g2 = (Graphics2D)g; if(color!=null) g2.setPaint(color); if(start!=null && end!=null) { if(selected==("elipse")) g2.drawOval(start.x, start.y,(end.x-start.x),(end.y-start.y)); else if(selected==("rect")) g2.drawRect(start.x, start.y, (end.x-start.x),(end.y-start.y)); else if(selected==("rrect")) g2.drawRoundRect(start.x, start.y, (end.x-start.x),(end.y-start.y),11,11); else if(selected==("line")) g2.drawLine(start.x,start.y,end.x,end.y); else if(selected==("poly")) { g2.drawLine(start.x,start.y,end.x,end.y); client.broadcast(start, "start", "poly", "drag", selectedcolor); client.broadcast(end, "end", "poly", "drag", selectedcolor); } } if(tooltip==true) { System.out.println(selected); if(selected=="text") { g2.drawString("|", tip.x, tip.y-5); g2.drawString("Click to add text", tip.x+10, tip.y+23); g2.drawString("__", label.x+post, label.y); } if(selected=="erase") { g2.setPaint(new Color(237,237,237)); g2.fillRect(tip.x-10,tip.y-10,10,10); g2.setPaint(color); g2.drawRect(tip.x-10,tip.y-10,10,10); } } } catch(Exception e) {} } //Function to draw the shape on image public void draw() { Graphics2D g2 = (Graphics2D) image.createGraphics(); Font font=new Font("Times New Roman",Font.PLAIN,14); g2.setFont(font); g2.setPaint(color); if(start!=null && end!=null) { if(selected=="line") g2.drawLine(start.x, start.y, end.x, end.y); else if(selected=="elipse") g2.drawOval(start.x, start.y, (end.x-start.x),(end.y-start.y)); else if(selected=="rect") g2.drawRect(start.x, start.y, (end.x-start.x),(end.y-start.y)); else if(selected==("rrect")) g2.drawRoundRect(start.x, start.y, (end.x-start.x),(end.y-start.y),11,11); else if(selected==("poly")) { g2.drawLine(start.x,start.y,end.x,end.y); client.broadcast(start, "start", "poly", "release", selectedcolor); client.broadcast(end, "end", "poly", "release", selectedcolor); } fillstart=start; fillend=end; fillshape=selected; } if(selected!="poly") { start=null; end=null; } if(label!=null) { if(selected==("text")) { g2.drawString(key,label.x,label.y); client.broadcast(label, key, "text", "release", selectedcolor); } } repaint(); g2.dispose(); } //Function which provides the erase functionality public void erase() { Graphics2D pic=(Graphics2D) image.createGraphics(); Color erasecolor=new Color(237,237,237); pic.setPaint(erasecolor); if(start!=null) pic.fillRect(start.x-10, start.y-10, 10, 10); } //To set the size of the image public void setImage(BufferedImage image) { this.image = image; } //Function to add buttons into the panel, calling this function returns a panel public JPanel shapeButtons() { JPanel shape=new JPanel(); shape.setBackground(new Color(181, 197, 210)); shape.setLayout(new GridLayout(5,2,2,4)); shape.setBounds(0, 2, 74, 166); rectangle.addActionListener(this); rectangle.setToolTipText("Rectangle"); line.addActionListener( this); line.setToolTipText("Line"); erase.addActionListener(this); erase.setToolTipText("Eraser"); roundrect.addActionListener(this); roundrect.setToolTipText("Round edge Rectangle"); polygon.addActionListener(this); polygon.setToolTipText("Polygon"); text.addActionListener(this); text.setToolTipText("Text"); fill.addActionListener(this); fill.setToolTipText("Fill with colour"); elipse.addActionListener(this); elipse.setToolTipText("Elipse"); save.addActionListener(this); shape.add(elipse); shape.add(rectangle); shape.add(roundrect); shape.add(polygon); shape.add(line); shape.add(text); shape.add(fill); shape.add(erase); shape.add(save); return shape; } public JPanel colourButtons() { JPanel colourbox=new JPanel(); colourbox.setBackground(new Color(181, 197, 210)); colourbox.setLayout(new GridLayout(8,2,8,8)); colourbox.setBounds(0,323,70,140); //colourbox.add(empty); for(int i=0;i<16;i++) { colourbutton[i]=new JButton(); colourbox.add(colourbutton[i]); if(i==0) colourbutton[0].setBackground(Color.black); else if(i==1) colourbutton[1].setBackground(Color.white); else if(i==2) colourbutton[2].setBackground(Color.red); else if(i==3) colourbutton[3].setBackground(Color.orange); else if(i==4) colourbutton[4].setBackground(Color.blue); else if(i==5) colourbutton[5].setBackground(Color.green); else if(i==6) colourbutton[6].setBackground(Color.pink); else if(i==7) colourbutton[7].setBackground(Color.magenta); else if(i==8) colourbutton[8].setBackground(Color.cyan); else if(i==9) colourbutton[9].setBackground(Color.black); else if(i==10) colourbutton[10].setBackground(Color.yellow); else if(i==11) colourbutton[11].setBackground(new Color(131,168,43)); else if(i==12) colourbutton[12].setBackground(new Color(132,0,210)); else if(i==13) colourbutton[13].setBackground(new Color(193,17,92)); else if(i==14) colourbutton[14].setBackground(new Color(129,82,50)); else if(i==15) colourbutton[15].setBackground(new Color(64,128,128)); colourbutton[i].addActionListener(this); } return colourbox; } public void fill() { if(selected=="fill") { Graphics2D g2 = (Graphics2D) image.getGraphics(); g2.setPaint(color); System.out.println("Fill"); if(fillshape=="elipse") g2.fillOval(fillstart.x, fillstart.y, (fillend.x-fillstart.x),(fillend.y-fillstart.y)); else if(fillshape=="rect") g2.fillRect(fillstart.x, fillstart.y, (fillend.x-fillstart.x),(fillend.y-fillstart.y)); else if(fillshape==("rrect")) g2.fillRoundRect(fillstart.x, fillstart.y, (fillend.x-fillstart.x),(fillend.y-fillstart.y),11,11); // else if(fillshape==("poly")) // g2.drawPolygon(x,y,2); } repaint(); } //To save the image drawn public void save() { try { ByteArrayOutputStream bos = new ByteArrayOutputStream(); JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(bos); JFileChooser fc = new JFileChooser(); fc.showSaveDialog(this); encoder.encode(image); byte[] jpgData = bos.toByteArray(); FileOutputStream fos = new FileOutputStream(fc.getSelectedFile()+".jpeg"); fos.write(jpgData); fos.close(); //add replce confirmation here } catch (IOException e) { System.out.println(e); } } public void mouseClicked(MouseEvent e) { } @Override public void mouseEntered(MouseEvent e) { } public void mouseExited(MouseEvent arg0) { } public void mousePressed(MouseEvent e) { if(selected=="line"||selected=="text") { start=e.getPoint(); client.broadcast(start,"start", selected,"press", selectedcolor); } else if(selected=="elipse"||selected=="rect"||selected=="rrect") mp = e.getPoint(); else if(selected=="poly") { if(first==true) { start=e.getPoint(); //client.broadcast(start,"start", selected,"press", selectedcolor); } else if(first==false) { end=e.getPoint(); repaint(); //client.broadcast(end,"end", selected,"press", selectedcolor); } } else if(selected=="erase") { start=e.getPoint(); erase(); } } public void mouseReleased(MouseEvent e) { if(selected=="text") { System.out.println("Reset"); key=""; post=0; label=new Point(); label=e.getPoint(); grabFocus(); } if(start!=null && end!=null) { if(selected=="line") { end=e.getPoint(); client.broadcast(end,"end", selected,"release", selectedcolor); draw(); } else if(selected=="elipse"||selected=="rect"||selected=="rrect") { end.x = Math.max(mp.x,e.getX()); end.y = Math.max(mp.y,e.getY()); client.broadcast(end,"end", selected,"release", selectedcolor); draw(); } else if(selected=="poly") { draw(); first=false; start=end; end=null; } } } public void mouseDragged(MouseEvent e) { if(end==null) end = new Point(); if(start==null) start = new Point(); if(selected=="line") { end=e.getPoint(); client.broadcast(end,"end", selected,"drag", selectedcolor); } else if(selected=="erase") { start=e.getPoint(); erase(); client.broadcast(start,"start", selected,"drag", selectedcolor); } else if(selected=="elipse"||selected=="rect"||selected=="rrect") { start.x = Math.min(mp.x,e.getX()); start.y = Math.min(mp.y,e.getY()); end.x = Math.max(mp.x,e.getX()); end.y = Math.max(mp.y,e.getY()); client.broadcast(start,"start", selected,"drag", selectedcolor); client.broadcast(end,"end", selected,"drag", selectedcolor); } else if(selected=="poly") end=e.getPoint(); System.out.println(tooltip); if(tooltip==true) { if(selected=="erase") { Graphics2D g2=(Graphics2D) getGraphics(); tip=e.getPoint(); g2.drawRect(tip.x-10,tip.y-10,10,10); } } repaint(); } public void mouseMoved(MouseEvent e) { if(selected=="text" ||selected=="erase") { tip=new Point(); tip=e.getPoint(); tooltip=true; repaint(); } } public void actionPerformed(ActionEvent e) { if(e.getSource()==elipse) selected="elipse"; else if(e.getSource()==line) selected="line"; else if(e.getSource()==rectangle) selected="rect"; else if(e.getSource()==erase) { selected="erase"; tooltip=true; System.out.println(selected); erase(); } else if(e.getSource()==roundrect) selected="rrect"; else if(e.getSource()==polygon) { selected="poly"; first=true; start=null; } else if(e.getSource()==text) { selected="text"; tooltip=true; } else if(e.getSource()==fill) { selected="fill"; fill(); } else if(e.getSource()==save) save(); if(e.getSource()==colourbutton[0]) { color=Color.black; selectedcolor="black"; } else if(e.getSource()==colourbutton[1]) { color=Color.white; selectedcolor="white"; } else if(e.getSource()==colourbutton[2]) { color=Color.red; selectedcolor="red"; } else if(e.getSource()==colourbutton[3]) { color=Color.orange; selectedcolor="orange"; } else if(e.getSource()==colourbutton[4]) { selectedcolor="blue"; color=Color.blue; } else if(e.getSource()==colourbutton[5]) { selectedcolor="green"; color=Color.green; } else if(e.getSource()==colourbutton[6]) { selectedcolor="pink"; color=Color.pink; } else if(e.getSource()==colourbutton[7]) { selectedcolor="magenta"; color=Color.magenta; } else if(e.getSource()==colourbutton[8]) { selectedcolor="cyan"; color=Color.cyan; } } @Override public void keyPressed(KeyEvent e) { //System.out.println(e.getKeyChar()+" : "+e.getKeyCode()); if(label!=null) { if(e.getKeyCode()==10) //Check for Enter key { label.y=label.y+14; key=""; post=0; repaint(); } else if(e.getKeyCode()==8) //Backspace { try{ Graphics2D g2 = (Graphics2D) image.getGraphics(); g2.setPaint(new Color(237,237,237)); g2.fillRect(label.x+post-7, label.y-13, 14, 17); if(post>0) post=post-6; keycode=0; key=key.substring(0, key.length()-1); System.out.println(key.substring(0, key.length())); repaint(); Point broadcastlabel=new Point(); broadcastlabel.x=label.x+post-7; broadcastlabel.y=label.y-13; client.broadcast(broadcastlabel, key, "text", "backspace", selectedcolor); } catch(Exception ex) {} } //Block invalid keys else if(!(e.getKeyCode()>=16 && e.getKeyCode()<=20 || e.getKeyCode()>=112 && e.getKeyCode()<=123 || e.getKeyCode()>=33 && e.getKeyCode()<=40 || e.getKeyCode()>=144 && e.getKeyCode()<=145 || e.getKeyCode()>=524 && e.getKeyCode()<=525 ||e.getKeyCode()==27||e.getKeyCode()==155 ||e.getKeyCode()==127)) { key=key+e.getKeyChar(); post=post+6; draw(); } } } @Override public void keyReleased(KeyEvent e) { } @Override public void keyTyped(KeyEvent e) { } } class Button extends JButton { String name; int i; public Button(String name) { this.name=name; try { UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); } catch (Exception e) { e.printStackTrace(); } } public Button(int i) { this.i=i; } public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D)g; g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); //g2.setStroke(new BasicStroke(1.2f)); if (name == "line") g.drawLine(5,5,30,30); if (name == "elipse") g.drawOval(5,7,25,20); if (name== "rect") g.drawRect(5,5,25,23); if (name== "roundrect") g.drawRoundRect(5,5,25,23,10,10); int a[]=new int[]{20,9,20,23,20}; int b[]=new int[]{9,23,25,20,9}; if (name== "poly") g.drawPolyline(a, b, 5); if (name== "text") g.drawString("Text",8, 24); } }

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• DSA signature verification input

  - by calccrypto

  What is the data inputted into DSA when PGP signs a message? From RFC4880, i found A Signature packet describes a binding between some public key and some data. The most common signatures are a signature of a file or a block of text, and a signature that is a certification of a User ID. im not sure if it is the entire public key, just the public key packet, or some other derivative of a pgp key packet. whatever it is, i cannot get the DSA signature to verify here is a sample im testing my program on: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 abcd -----BEGIN PGP SIGNATURE----- Version: BCPG v1.39 iFkEARECABkFAk0z65ESHGFiYyAodGVzdCBrZXkpIDw+AAoJEC3Jkh8+bnkusO0A oKG+HPF2Qrsth2zS9pK+eSCBSypOAKDBgC2Z0vf2EgLiiNMk8Bxpq68NkQ== =gq0e -----END PGP SIGNATURE----- Dumped from pgpdump.net Old: Signature Packet(tag 2)(89 bytes) Ver 4 - new Sig type - Signature of a canonical text document(0x01). Pub alg - DSA Digital Signature Algorithm(pub 17) Hash alg - SHA1(hash 2) Hashed Sub: signature creation time(sub 2)(4 bytes) Time - Mon Jan 17 07:11:13 UTC 2011 Hashed Sub: signer's User ID(sub 28)(17 bytes) User ID - abc (test key) <> Sub: issuer key ID(sub 16)(8 bytes) Key ID - 0x2DC9921F3E6E792E Hash left 2 bytes - b0 ed DSA r(160 bits) - a1 be 1c f1 76 42 bb 2d 87 6c d2 f6 92 be 79 20 81 4b 2a 4e DSA s(160 bits) - c1 80 2d 99 d2 f7 f6 12 02 e2 88 d3 24 f0 1c 69 ab af 0d 91 -> hash(DSA q bits) and the public key for it is: -----BEGIN PGP PUBLIC KEY BLOCK----- Version: BCPG v1.39 mOIETTPqeBECALx+i9PIc4MB2DYXeqsWUav2cUtMU1N0inmFHSF/2x0d9IWEpVzE kRc30PvmEHI1faQit7NepnHkkphrXLAoZukAoNP3PB8NRQ6lRF6/6e8siUgJtmPL Af9IZOv4PI51gg6ICLKzNO9i3bcUx4yeG2vjMOUAvsLkhSTWob0RxWppo6Pn6MOg dMQHIM5sDH0xGN0dOezzt/imAf9St2B0HQXVfAAbveXBeRoO7jj/qcGx6hWmsKUr BVzdQhBk7Sku6C2KlMtkbtzd1fj8DtnrT8XOPKGp7/Y7ASzRtBFhYmMgKHRlc3Qg a2V5KSA8PohGBBMRAgAGBQJNM+p5AAoJEC3Jkh8+bnkuNEoAnj2QnqGtdlTgUXCQ Fyvwk5wiLGPfAJ4jTGTL62nWzsgrCDIMIfEG2shm8bjMBE0z6ngQAgCUlP7AlfO4 XuKGVCs4NvyBpd0KA0m0wjndOHRNSIz44x24vLfTO0GrueWjPMqRRLHO8zLJS/BX O/BHo6ypjN87Af0VPV1hcq20MEW2iujh3hBwthNwBWhtKdPXOndJGZaB7lshLJuW v9z6WyDNXj/SBEiV1gnPm0ELeg8Syhy5pCjMAgCFEc+NkCzcUOJkVpgLpk+VLwrJ /Wi9q+yCihaJ4EEFt/7vzqmrooXWz2vMugD1C+llN6HkCHTnuMH07/E/2dzciEYE GBECAAYFAk0z6nkACgkQLcmSHz5ueS7NTwCdED1P9NhgR2LqwyS+AEyqlQ0d5joA oK9xPUzjg4FlB+1QTHoOhuokxxyN =CTgL -----END PGP PUBLIC KEY BLOCK----- the public key packet of the key is mOIETTPqeBECALx+i9PIc4MB2DYXeqsWUav2cUtMU1N0inmFHSF/2x0d9IWEpVzEkRc30PvmEHI1faQi t7NepnHkkphrXLAoZukAoNP3PB8NRQ6lRF6/6e8siUgJtmPLAf9IZOv4PI51gg6ICLKzNO9i3bcUx4ye G2vjMOUAvsLkhSTWob0RxWppo6Pn6MOgdMQHIM5sDH0xGN0dOezzt/imAf9St2B0HQXVfAAbveXBeRoO 7jj/qcGx6hWmsKUrBVzdQhBk7Sku6C2KlMtkbtzd1fj8DtnrT8XOPKGp7/Y7ASzR in radix 64 i have tried many different combinations of sha1(< some data + 'abcd'),but the calculated value v never equals r, of the signature i know that the pgp implementation i used to create the key and signature is correct. i also know that my DSA implementation and PGP key data extraction program are correct. thus, the only thing left is the data to hash. what is the correct data to be hashed?

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• Processing incorrect mac addresses from 802.11 frames with pcap

  - by Quentin Swain

  I'm working throurgh a project with pcap and wireless. Following an example posted in response to oe of my earlier questions I am trying to extract the mac addresses from wireless frames. I have created structures for the radiotap header and a basic management frame. For some reason when it comes to trying to output the mac addresses I am printing out the wrong data. When I compare to wireshark I don't see why the radio tap data is printing out correctly but the mac addresses are not. I don't see any additional padding in the hex dump that wireshark displays when i look at the packets and compare the packets that I have captured. I am somewhat famialar with c but not an expert so maybe I am not using the pointers and structures properly could someone help show me what I am doing wrong? Thanks, Quentin // main.c // MacSniffer // #include <pcap.h> #include <string.h> #include <stdlib.h> #define MAXBYTES2CAPTURE 65535 #ifdef WORDS_BIGENDIAN typedef struct frame_control { unsigned int subtype:4; /*frame subtype field*/ unsigned int protoVer:2; /*frame type field*/ unsigned int version:2; /*protocol version*/ unsigned int order:1; unsigned int protected:1; unsigned int moreDate:1; unsigned int power_management:1; unsigned int retry:1; unsigned int moreFrag:1; unsigned int fromDS:1; unsigned int toDS:1; }frame_control; struct ieee80211_radiotap_header{ u_int8_t it_version; u_int8_t it_pad; u_int16_t it_len; u_int32_t it_present; u_int64_t MAC_timestamp; u_int8_t flags; u_int8_t dataRate; u_int16_t channelfrequency; u_int16_t channFreq_pad; u_int16_t channelType; u_int16_t channType_pad; u_int8_t ssiSignal; u_int8_t ssiNoise; u_int8_t antenna; }; #else typedef struct frame_control { unsigned int protoVer:2; /* protocol version*/ unsigned int type:2; /*frame type field (Management,Control,Data)*/ unsigned int subtype:4; /* frame subtype*/ unsigned int toDS:1; /* frame coming from Distribution system */ unsigned int fromDS:1; /*frame coming from Distribution system */ unsigned int moreFrag:1; /* More fragments?*/ unsigned int retry:1; /*was this frame retransmitted*/ unsigned int powMgt:1; /*Power Management*/ unsigned int moreDate:1; /*More Date*/ unsigned int protectedData:1; /*Protected Data*/ unsigned int order:1; /*Order*/ }frame_control; struct ieee80211_radiotap_header{ u_int8_t it_version; u_int8_t it_pad; u_int16_t it_len; u_int32_t it_present; u_int64_t MAC_timestamp; u_int8_t flags; u_int8_t dataRate; u_int16_t channelfrequency; u_int16_t channelType; int ssiSignal:8; int ssiNoise:8; }; #endif struct wi_frame { u_int16_t fc; u_int16_t wi_duration; u_int8_t wi_add1[6]; u_int8_t wi_add2[6]; u_int8_t wi_add3[6]; u_int16_t wi_sequenceControl; // u_int8_t wi_add4[6]; //unsigned int qosControl:2; //unsigned int frameBody[23124]; }; void processPacket(u_char *arg, const struct pcap_pkthdr* pkthdr, const u_char* packet) { int i= 0, *counter = (int *) arg; struct ieee80211_radiotap_header *rh =(struct ieee80211_radiotap_header *)packet; struct wi_frame *fr= (struct wi_frame *)(packet + rh->it_len); u_char *ptr; //printf("Frame Type: %d",fr->wi_fC->type); printf("Packet count: %d\n", ++(*counter)); printf("Received Packet Size: %d\n", pkthdr->len); if(rh->it_version != NULL) { printf("Radiotap Version: %d\n",rh->it_version); } if(rh->it_pad!=NULL) { printf("Radiotap Pad: %d\n",rh->it_pad); } if(rh->it_len != NULL) { printf("Radiotap Length: %d\n",rh->it_len); } if(rh->it_present != NULL) { printf("Radiotap Present: %c\n",rh->it_present); } if(rh->MAC_timestamp != NULL) { printf("Radiotap Timestamp: %u\n",rh->MAC_timestamp); } if(rh->dataRate != NULL) { printf("Radiotap Data Rate: %u\n",rh->dataRate); } if(rh->channelfrequency != NULL) { printf("Radiotap Channel Freq: %u\n",rh->channelfrequency); } if(rh->channelType != NULL) { printf("Radiotap Channel Type: %06x\n",rh->channelType); } if(rh->ssiSignal != NULL) { printf("Radiotap SSI signal: %d\n",rh->ssiSignal); } if(rh->ssiNoise != NULL) { printf("Radiotap SSI Noise: %d\n",rh->ssiNoise); } ptr = fr->wi_add1; int k= 6; printf("Destination Address:"); do{ printf("%s%X",(k==6)?" ":":",*ptr++); } while(--k>0); printf("\n"); ptr = fr->wi_add2; k=0; printf("Source Address:"); do{ printf("%s%X",(k==6)?" ":":",*ptr++); }while(--k>0); printf("\n"); ptr = fr->wi_add3; k=0; do{ printf("%s%X",(k==6)?" ":":",*ptr++); } while(--k>0); printf("\n"); /* for(int j = 0; j < 23124;j++) { if(fr->frameBody[j]!= NULL) { printf("%x",fr->frameBody[j]); } } */ for (i = 0;i<pkthdr->len;i++) { if(isprint(packet[i +rh->it_len])) { printf("%c",packet[i + rh->it_len]); } else{printf(".");} //print newline after each section of the packet if((i%16 ==0 && i!=0) ||(i==pkthdr->len-1)) { printf("\n"); } } return; } int main(int argc, char** argv) { int count = 0; pcap_t* descr = NULL; char errbuf[PCAP_ERRBUF_SIZE], *device = NULL; struct bpf_program fp; char filter[]="wlan broadcast"; const u_char* packet; memset(errbuf,0,PCAP_ERRBUF_SIZE); device = argv[1]; if(device == NULL) { fprintf(stdout,"Supply a device name "); } descr = pcap_create(device,errbuf); pcap_set_rfmon(descr,1); pcap_set_promisc(descr,1); pcap_set_snaplen(descr,30); pcap_set_timeout(descr,10000); pcap_activate(descr); int dl =pcap_datalink(descr); printf("The Data Link type is %s",pcap_datalink_val_to_name(dl)); //pcap_dispatch(descr,MAXBYTES2CAPTURE,1,512,errbuf); //Open device in promiscuous mode //descr = pcap_open_live(device,MAXBYTES2CAPTURE,1,512,errbuf); /* if(pcap_compile(descr,&fp,filter,0,PCAP_NETMASK_UNKNOWN)==-1) { fprintf(stderr,"Error compiling filter\n"); exit(1); } if(pcap_setfilter(descr,&fp)==-1) { fprintf(stderr,"Error setting filter\n"); exit(1); } */ pcap_loop(descr,0, processPacket, (u_char *) &count); return 0; }

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• SIGSEGV problem

  - by sickmate

  I'm designing a protocol (in C) to implement the layered OSI network structure, using cnet (http://www.csse.uwa.edu.au/cnet/). I'm getting a SIGSEGV error at runtime, however cnet compiles my source code files itself (I can't compile it through gcc) so I can't easily use any debugging tools such as gdb to find the error. Here's the structures used, and the code in question: typedef struct { char *data; } DATA; typedef struct { CnetAddr src_addr; CnetAddr dest_addr; PACKET_TYPE type; DATA data; } Packet; typedef struct { int length; int checksum; Packet datagram; } Frame; static void keyboard(CnetEvent ev, CnetTimerID timer, CnetData data) { char line[80]; int length; length = sizeof(line); CHECK(CNET_read_keyboard((void *)line, (unsigned int *)&length)); // Reads input from keyboard if(length > 1) { /* not just a blank line */ printf("\tsending %d bytes - \"%s\"\n", length, line); application_downto_transport(1, line, &length); } } void application_downto_transport(int link, char *msg, int *length) { transport_downto_network(link, msg, length); } void transport_downto_network(int link, char *msg, int *length) { Packet *p; DATA *d; p = (Packet *)malloc(sizeof(Packet)); d = (DATA *)malloc(sizeof(DATA)); d->data = msg; p->data = *d; network_downto_datalink(link, (void *)p, length); } void network_downto_datalink(int link, Packet *p, int *length) { Frame *f; // Encapsulate datagram and checksum into a Frame. f = (Frame *)malloc(sizeof(Frame)); f->checksum = CNET_crc32((unsigned char *)(p->data).data, *length); // Generate 32-bit CRC for the data. f->datagram = *p; f->length = sizeof(f); //Pass Frame to the CNET physical layer to send Frame to the require link. CHECK(CNET_write_physical(link, (void *)f, (size_t *)f->length)); free(p->data); free(p); free(f); } I managed to find that the line: CHECK(CNET_write_physical(link, (void *)f, (size_t *)f-length)); is causing the segfault but I can't work out why. Any help is greatly appreciated.

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• paket drop and splits in udp tunnel

  - by sr-dusad

  hi guys ! Currently I am working on video conferencing project.For this i m using pwnat for nat traversing. pwnat is based on udp tunneling.I m using the TCP connection for data transmission. My problem is that when i send a packet , it does not reach properly at its destination side . Sometime it drops the packet and many times it breaks ( split ) the packet into pieces. Please Help me .. How can i send and recieve a packet into single piece. So, i can draw image properly and play sound. Any kind of help will be appriciated . Thanks in advance

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• TCP sequence number question

  - by Meta

  This is more of a theoretical question than an actual problem I have. If I understand correctly, the sequence number in the TCP header of a packet is the index of the first byte in the packet in the whole stream, correct? If that is the case, since the sequence number is an unsigned 32-bit integer, then what happens after more than FFFFFFFF = 4294967295 bytes are transferred? Will the sequence number wrap around, or will the sender send a SYN packet to restart at 0?

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• C++/CLI HTTP Proxy problems...

  - by darkantimatter

  Hi, I'm trying(very hard) to make a small HTTP Proxy server which I can use to save all communications to a file. Seeing as I dont really have any experience in the area, I used a class from codeproject.com and some associated code to get started (It was made in the old CLI syntax, so I converted it). I couldn't get it working, so I added lots more code to make it work (threads etc), and now it sort of works. Basically, it recieves something from a client (I just configured Mozilla Firefox to route its connections through this proxy) and then routes it to google.com. After it sends Mozilla's data to google, recieves a responce, and sends that to Mozilla. This works fine, but then the proxy fails to recieve any data from Mozilla. It just loops in the Sleep(50) section. Anyway, heres the code: ProxyTest.cpp: #include "stdafx.h" #include "windows.h" #include "CHTTPProxy.h" public ref class ClientThread { public: System::Net::Sockets::TcpClient ^ pClient; CHttpProxy ^ pProxy; System::Int32 ^ pRecieveBufferSize; System::Threading::Thread ^ Thread; ClientThread(System::Net::Sockets::TcpClient ^ sClient, CHttpProxy ^ sProxy, System::Int32 ^ sRecieveBufferSize) { pClient = sClient; pProxy = sProxy; pRecieveBufferSize = sRecieveBufferSize; }; void StartReading() { Thread = gcnew System::Threading::Thread(gcnew System::Threading::ThreadStart(this,&ClientThread::ThreadEntryPoint)); Thread->Start(); }; void ThreadEntryPoint() { char * bytess; bytess = new char[(int)pRecieveBufferSize]; memset(bytess, 0, (int)pRecieveBufferSize); array<unsigned char> ^ bytes = gcnew array<unsigned char>((int)pRecieveBufferSize); array<unsigned char> ^ sendbytes; do { if (pClient->GetStream()->DataAvailable) { try { do { Sleep(100); //Lets wait for whole packet to get cached (If it even does...) unsigned int k = pClient->GetStream()->Read(bytes, 0, (int)pRecieveBufferSize); //Read it for(unsigned int i=0; i<(int)pRecieveBufferSize; i++) bytess[i] = bytes[i]; Console::WriteLine("Packet Received:\n"+gcnew System::String(bytess)); pProxy->SendToServer(bytes,pClient->GetStream()); //Now send it to google! pClient->GetStream()->Flush(); } while(pClient->GetStream()->DataAvailable); } catch (Exception ^ e) { break; } } else { Sleep(50); //It just loops here because it thinks mozilla isnt sending anything if (!(pClient->Connected)) break; }; } while (pClient->GetStream()->CanRead); delete [] bytess; pClient->Close(); }; }; int main(array<System::String ^> ^args) { System::Collections::Generic::Stack<ClientThread ^> ^ Clients = gcnew System::Collections::Generic::Stack<ClientThread ^>(); System::Net::Sockets::TcpListener ^ pTcpListener = gcnew System::Net::Sockets::TcpListener(8080); pTcpListener->Start(); System::Net::Sockets::TcpClient ^ pTcpClient; while (1) { pTcpClient = pTcpListener->AcceptTcpClient(); //Wait for client ClientThread ^ Client = gcnew ClientThread(pTcpClient, gcnew CHttpProxy("www.google.com.au", 80), pTcpClient->ReceiveBufferSize); //Make a new object for this client Client->StartReading(); //Start the thread Clients->Push(Client); //Add it to the list }; pTcpListener->Stop(); return 0; } CHTTPProxy.h, from http://www.codeproject.com/KB/IP/howtoproxy.aspx with a lot of modifications: //THIS FILE IS FROM http://www.codeproject.com/KB/IP/howtoproxy.aspx. I DID NOT MAKE THIS! BUT I HAVE MADE SEVERAL MODIFICATIONS! #using <mscorlib.dll> #using <SYSTEM.DLL> using namespace System; using System::Net::Sockets::TcpClient; using System::String; using System::Exception; using System::Net::Sockets::NetworkStream; #include <stdio.h> ref class CHttpProxy { public: CHttpProxy(System::String ^ szHost, int port); System::String ^ m_host; int m_port; void SendToServer(array<unsigned char> ^ Packet, System::Net::Sockets::NetworkStream ^ sendstr); }; CHttpProxy::CHttpProxy(System::String ^ szHost, int port) { m_host = gcnew System::String(szHost); m_port = port; } void CHttpProxy::SendToServer(array<unsigned char> ^ Packet, System::Net::Sockets::NetworkStream ^ sendstr) { TcpClient ^ tcpclnt = gcnew TcpClient(); try { tcpclnt->Connect(m_host,m_port); } catch (Exception ^ e ) { Console::WriteLine(e->ToString()); return; } // Send it if ( tcpclnt ) { NetworkStream ^ networkStream; networkStream = tcpclnt->GetStream(); int size = Packet->Length; networkStream->Write(Packet, 0, size); array<unsigned char> ^ bytes = gcnew array<unsigned char>(tcpclnt->ReceiveBufferSize); char * bytess = new char[tcpclnt->ReceiveBufferSize]; Sleep(500); //Wait for responce do { unsigned int k = networkStream->Read(bytes, 0, (int)tcpclnt->ReceiveBufferSize); //Read from google for(unsigned int i=0; i<k; i++) { bytess[i] = bytes[i]; if (bytess[i] == 0) bytess[i] = ' '; //Dont terminate the string if (bytess[i] < 8) bytess[i] = ' '; //Somethings making the computer beep, and its not 7?!?! }; Console::WriteLine("\n\nAbove packet sent to google. Google Packet Received:\n"+gcnew System::String(bytess)); sendstr->Write(bytes,0,k); //Send it to mozilla Console::WriteLine("\n\nAbove packet sent to client..."); //Sleep(1000); } while(networkStream->DataAvailable); delete [] bytess; } return; } Any help would be much appreciated, I've tried for hours.

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• protocol parsing in c

  - by nomad.alien

  I have been playing around with trying to implement some protocol decoders, but each time I run into a "simple" problem and I feel the way I am solving the problem is not optimal and there must be a better way to do things. I'm using C. Currently I'm using some canned data and reading it in as a file, but later on it would be via TCP or UDP. Here's the problem. I'm currently playing with a binary protocol at work. All fields are 8 bits long. The first field(8bits) is the packet type. So I read in the first 8 bits and using a switch/case I call a function to read in the rest of the packet as I then know the size/structure of it. BUT...some of these packets have nested packets inside them, so when I encounter that specific packet I then have to read another 8-16 bytes have another switch/case to see what the next packet type is and on and on. (Luckily the packets are only nested 2 or 3 deep). Only once I have the whole packet decoded can I handle it over to my state machine for processing. I guess this can be a more general question as well. How much data do you have to read at a time from the socket? As much as possible? As much as what is "similar" in the protocol headers? So even though this protocol is fairly basic, my code is a whole bunch of switch/case statements and I do a lot of reading from the file/socket which I feel is not optimal. My main aim is to make this decoder as fast as possible. To the more experienced people out there, is this the way to go or is there a better way which I just haven't figured out yet? Any elegant solution to this problem?

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• How to Broadcast to a shutdown system using java?

  - by pirates-iiita

  We use socket.send(packet) function in java to send a "packet" to a given port. My problem is that i have to send a packet to a shutdown system using UDP protocol. The problem with send() function is that first it verifies whether the host IP is multicast or not. Now my local area network is of broadcast type. So i am having problem is using this function. can anyone please give me a way ?

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