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  • Guests can't access KVM host server by name although nslookup and dig returns correct record

    - by user190196
    So I have a KVM host that also runs an apache server with some yum repos. The VM guests are connected to the default virtual network, which is configured to offer DHCP and forwarding with NAT on virbr0 (192.168.12.1). The guests can successfully access the yum repos on the host by IP address, so for example curl 192.168.122.1/repo1 returns the content without problems. But I'd like to have the guests be able to reach the web server on the host by name rather IP address. I added the desired name record to the host's /etc/hosts file and libvirt's dnsmasq service seems to be serving that correctly to the guests since nslookup and dig successfully resolve the name on the guests: [root@localhost ~]# nslookup repo Server: 192.168.122.1 Address: 192.168.122.1#53 Name: repo Address: 192.168.122.1 [root@localhost ~]# dig repo ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.17.rc1.el6 <<>> repo ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55938 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;repo. IN A ;; ANSWER SECTION: repo. 0 IN A 192.168.122.1 ;; Query time: 0 msec ;; SERVER: 192.168.122.1#53(192.168.122.1) ;; WHEN: Tue Sep 17 02:10:46 2013 ;; MSG SIZE rcvd: 38 But curl/ping/etc still fail: [root@localhost ~]# curl repo curl: (6) Couldn't resolve host 'repo' While a request via ip address works: [root@localhost ~]# curl 192.168.122.1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <html> <head> <title>Index of /</title> [...] Same with ping: [root@localhost ~]# ping repo ping: unknown host repo [root@localhost ~]# ping 192.168.122.1 PING 192.168.122.1 (192.168.122.1) 56(84) bytes of data. 64 bytes from 192.168.122.1: icmp_seq=1 ttl=64 time=0.110 ms 64 bytes from 192.168.122.1: icmp_seq=2 ttl=64 time=0.146 ms 64 bytes from 192.168.122.1: icmp_seq=3 ttl=64 time=0.191 ms ^C --- 192.168.122.1 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2298ms rtt min/avg/max/mdev = 0.110/0.149/0.191/0.033 ms I tried adding repo 192.168.122.1 to the guests' /etc/hosts files but still no dice. Also tried changing guests' /etc/nsswitch.conf with both: hosts: files dns and hosts: dns files I've read the relevant libvirt documentation and I'm not sure where else to learn more about this and be able to move forward with it.

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  • Some DHCP clients end up with wrong DNS server

    - by Nic Waller
    The scenario: DC running Windows Server 2008 R2 providing DNS + DHCP Cisco 1811 Router as the gateway 30 Windows XP DHCP clients on the LAN The problem: Some workstations are spontaneously switching to an incorrect DNS server. Specifically, ipconfig /all shows that they start using the gateway as a DNS server. This happens about 5-10 times a day to various computers, sometimes more than once per day. The workaround: Repairing the connection on the XP client always fixes the problem, and the correct DNS server address is obtained. We lost our main DNS/DHCP machine a week ago, and had to bring this one online as a spare. We've been having this issue since then. DHCP leases on the old and new servers are configured for "wired" (8 day) duration. There are definitely no other DHCP servers active on the LAN. So far there is no discernible pattern about which clients will show this problem, or when. When I ran DCDIAG /test:DNS it came back clean. Manual inspection of the DNS zone shows that all the records are appearing as expected, with no traces of the previous machine in there. Update Feb 27: Added screenshots. Here is a screenshot of the DHCP scope options on the 2008 R2 server. And here is a screenshot of ipconfig /all running on a healthy host. I don't have any ailing hosts at the moment, but will grab a screencap next time it happens. Update Feb 28: More screenshots. Here's a screenshot of DHCP and DNS traffic from a healthy client when repairing the local area connection. There's definitely only one server responding, but it does seem strange that the negotiation takes place twice. I'll try to get a similar capture from a sick machine this coming week. Update Mar 01: Caught a bad ipconfig. Here's a screenshot of ipconfig /all from a client that had this issue. It says the lease was issued this morning, but it doesn't even have an entry for the secondary DNS I set up yesterday. Both DNS servers were discovered properly when repairing the connection. Update Mar 01: It even got the sysadmin! This issue finally affected my personal workstation this morning. Unfortunately I had just rebooted and wasn't running a packet dump at the time. I set up a secondary server yesterday, and was logging all DNS traffic to it. My machine had not contacted the secondary DNS in over half an hour, so that says to me that it's just spontaneously reverting to the gateway without even failing over to secondary DNS first. Today I swapped the order of the DNS servers in DHCP, so the secondary is primary and vice versa. I will update again once I know how that goes.

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  • 6to4 tunnel: cannot ping6 to ipv6.google.com?

    - by quanta
    Hi folks, Follow the Setup of 6to4 tunnel guide, I want to test ipv6 connectivity, but I cannot ping6 to ipv6.google.com. Details below: # traceroute 192.88.99.1 traceroute to 192.88.99.1 (192.88.99.1), 30 hops max, 40 byte packets 1 static.vdc.vn (123.30.53.1) 1.514 ms 2.622 ms 3.760 ms 2 static.vdc.vn (123.30.63.117) 0.608 ms 0.696 ms 0.735 ms 3 static.vdc.vn (123.30.63.101) 0.474 ms 0.477 ms 0.506 ms 4 203.162.231.214 (203.162.231.214) 11.327 ms 11.320 ms 11.312 ms 5 static.vdc.vn (222.255.165.34) 11.546 ms 11.684 ms 11.768 ms 6 203.162.217.26 (203.162.217.26) 42.460 ms 42.424 ms 42.401 ms 7 218.188.104.173 (218.188.104.173) 42.489 ms 42.462 ms 42.415 ms 8 218.189.5.10 (218.189.5.10) 42.613 ms 218.189.5.42 (218.189.5.42) 42.273 ms 42.300 ms 9 d1-26-224-143-118-on-nets.com (118.143.224.26) 205.752 ms d1-18-224-143-118-on-nets.com (118.143.224.18) 207.130 ms d1-14-224-143-118-on-nets.com (118.143.224.14) 206.970 ms 10 218.189.5.150 (218.189.5.150) 207.456 ms 206.349 ms 206.941 ms 11 * * * 12 10gigabitethernet2-1.core1.lax1.he.net (72.52.92.121) 214.087 ms 214.426 ms 214.818 ms 13 192.88.99.1 (192.88.99.1) 207.215 ms 199.270 ms 209.391 ms # ifconfig tun6to4 tun6to4 Link encap:IPv6-in-IPv4 inet6 addr: 2002:x:x::/16 Scope:Global inet6 addr: ::x.x.x.x/128 Scope:Compat UP RUNNING NOARP MTU:1480 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:11 dropped:0 overruns:0 carrier:11 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) # iptunnel sit0: ipv6/ip remote any local any ttl 64 nopmtudisc tun6to4: ipv6/ip remote any local x.x.x.x ttl 64 # ip -6 route show ::/96 via :: dev tun6to4 metric 256 expires 21332777sec mtu 1480 advmss 1420 hoplimit 4294967295 2002::/16 dev tun6to4 metric 256 expires 21332794sec mtu 1480 advmss 1420 hoplimit 4294967295 fe80::/64 dev eth0 metric 256 expires 15674592sec mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev eth1 metric 256 expires 15674597sec mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev tun6to4 metric 256 expires 21332794sec mtu 1480 advmss 1420 hoplimit 4294967295 default via ::192.88.99.1 dev tun6to4 metric 1 expires 21332861sec mtu 1480 advmss 1420 hoplimit 4294967295 # ping6 -n -c 4 ipv6.google.com PING ipv6.google.com(2404:6800:8005::68) 56 data bytes From 2002:x:x:: icmp_seq=0 Destination unreachable: Address unreachable From 2002:x:x:: icmp_seq=1 Destination unreachable: Address unreachable From 2002:x:x:: icmp_seq=2 Destination unreachable: Address unreachable From 2002:x:x:: icmp_seq=3 Destination unreachable: Address unreachable --- ipv6.google.com ping statistics --- 4 packets transmitted, 0 received, +4 errors, 100% packet loss, time 2999ms What is my problem? Thanks,

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  • radvd is not assigning prefix

    - by Samik
    I'm currently trying to setup IPv6 address auto-configuration with router advertisement daemon (radvd) on a virtual machine running CentOS 6.5. But the eth0 interface is not obtaining that prefix. I've obtained the ULA prefix from here. Contents of /etc/sysctl.conf # Kernel sysctl configuration file for Red Hat Linux # # For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and # sysctl.conf(5) for more details. # Controls IP packet forwarding net.ipv4.ip_forward = 0 net.ipv6.conf.all.forwarding = 1 # Controls source route verification net.ipv4.conf.default.rp_filter = 1 # Do not accept source routing net.ipv4.conf.default.accept_source_route = 0 # Controls the System Request debugging functionality of the kernel kernel.sysrq = 0 # Controls whether core dumps will append the PID to the core filename. # Useful for debugging multi-threaded applications. kernel.core_uses_pid = 1 # Controls the use of TCP syncookies net.ipv4.tcp_syncookies = 1 # Disable netfilter on bridges. net.bridge.bridge-nf-call-ip6tables = 0 net.bridge.bridge-nf-call-iptables = 0 net.bridge.bridge-nf-call-arptables = 0 # Controls the default maxmimum size of a mesage queue kernel.msgmnb = 65536 # Controls the maximum size of a message, in bytes kernel.msgmax = 65536 # Controls the maximum shared segment size, in bytes kernel.shmmax = 68719476736 # Controls the maximum number of shared memory segments, in pages kernel.shmall = 4294967296 Contents of /etc/radvd.conf # NOTE: there is no such thing as a working "by-default" configuration file. # At least the prefix needs to be specified. Please consult the radvd.conf(5) # man page and/or /usr/share/doc/radvd-*/radvd.conf.example for help. # # interface eth0 { AdvSendAdvert on; MinRtrAdvInterval 3; MaxRtrAdvInterval 10; AdvDefaultPreference low; AdvHomeAgentFlag off; prefix fd8a:8d9d:808f:1::/64 { AdvOnLink on; AdvAutonomous on; AdvRouterAddr on; }; }; Contents of /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE=eth0 HWADDR=52:54:00:74:d7:46 TYPE=Ethernet UUID=af5db1cb-e809-4098-be1a-5a74dbb767b1 ONBOOT=yes NM_CONTROLLED=no BOOTPROTO=dhcp IPV6INIT=yes IPV6_AUTOCONF=yes I've also enabled radvd at startup through chkconfig. Though I noticed that radvd is starting after interfaces are brought up. I've tried restarting the network service afterwards but still I get the following link-local address only #ip -6 addr show 1: lo: mtu 16436 inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: mtu 1500 qlen 1000 inet6 fe80::5054:ff:fe74:d746/64 scope link valid_lft forever preferred_lft forever Edit: Based on the answer given by Sander Steffann I still need clarification on some points but I'm posting here what worked. Contents of /etc/sysconfig/network NETWORKING=yes HOSTNAME=syslog-ng-server NETWORKING_IPV6=yes IPV6FORWARDING=yes Contents of /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE=eth0 HWADDR=52:54:00:74:d7:46 TYPE=Ethernet UUID=af5db1cb-e809-4098-be1a-5a74dbb767b1 ONBOOT=yes NM_CONTROLLED=no BOOTPROTO=dhcp IPV6INIT=yes IPV6_AUTOCONF=yes IPV6FORWARDING=no Removed following line from /etc/sysctl.conf net.ipv6.conf.all.forwarding = 1 Contents of /etc/radvd.conf is as previous.

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  • Total newb having SSH tunnel and remote MySQL access problems

    - by kscott
    I don't often work with linux or need to SSH tunnel into remote MySQL databases, so pardon my ignorance. I'm using Windows 7 and am needing to connect to a remote MySQL instance on a Linux server. For months I had been using the HeidiSQL client application successfully. Today two things happened: the DB moved to a new server and I updated HeidiSQL, now I cannot log in to the MySQL server, when attempting I get this message from Heidi: SQL Error (2003) in statement #0: Can't connect to MySQL server on 'localhost' (10061) If I use Putty, I can connect to the server and get MySQL access through command line, including fetching data from the DB. I assume this means my credentials and address are correct, but do not understand why putting those same details into HeidiSQL's SSH tunnel info won't work. I also downloaded the MySQL Workbench and attempted to set up a connection through that client and got this message: Cannot Connect to Database Server Your connection attempt failed for user 'myusername' from your host to server at localhost:3306: Lost connection to MySQL server at 'reading initial communication packet', system error: 0 Please: 1 Check that mysql is running on server localhost 2 Check that mysql is running on port 3306 (note: 3306 is the default, but this can be changed) 3 Check the myusername has rights to connect to localhost from your address (mysql rights define what clients can connect to the server and from which machines) 4 Make sure you are both providing a password if needed and using the correct password for localhost connecting from the host address you're connecting from From Googling around I see that it could be related to the MySQL bind-address, but I am a third party sub-contractor with no access to the MySQL settings of this box and the system admin is assuring me that I'm an idiot and need to figure it out on my end. This is completely possible but I don't know what else to try. Edit 1 - The client settings I am using In Heidi and MySQL Workbench I am using the following: SSH host + port: theHostnameOfTheRemoteServer.com:22 {this is the same host I can Putty to} SSH Username: mySSHusername {the same user name I use for my Putty connection} SSH Password: mySSHpassword {the same password for the Putty connection} Local port: 3307 {this is on the SSH settings tab and was defaulted to 3307 by Heidi, changing it to 3306 gives me a different error: SQL Error (1045) in statement #0: Access denied for user 'mySQLusername'@'localhost' (using password: YES)"} MySQL host: theHostnameOfTheRemoteServer.com {consensus seems to be I should use 'localhost' here} MySQL User: mySQLusername {which I can connect with once in with Putty} MySQL Password: mySQLpassword {which works once in with Putty} Port: 3306

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  • How do I protect a low budget network from rogue DHCP servers?

    - by Kenned
    I am helping a friend manage a shared internet connection in an apartment buildling with 80 apartments - 8 stairways with 10 apartments in each. The network is laid out with the internet router at one end of the building, connected to a cheap non-managed 16 port switch in the first stairway where the first 10 apartments are also connected. One port is connected to another 16 port cheapo switch in the next stairway, where those 10 apartments are connected, and so forth. Sort of a daisy chain of switches, with 10 apartments as spokes on each "daisy". The building is a U-shape, approximately 50 x 50 meters, 20 meters high - so from the router to the farthest apartment it’s probably around 200 meters including up-and-down stairways. We have a fair bit of problems with people hooking up wifi-routers the wrong way, creating rogue DHCP servers which interrupt large groups of the users and we wish to solve this problem by making the network smarter (instead of doing a physical unplugging binary search). With my limited networking skills, I see two ways - DHCP-snooping or splitting the entire network into separate VLANS for each apartment. Separate VLANS gives each apartment their own private connection to the router, while DHCP snooping will still allow LAN gaming and file sharing. Will DHCP snooping work with this kind of network topology, or does that rely on the network being in a proper hub-and-spoke-configuration? I am not sure if there are different levels of DHCP snooping - say like expensive Cisco switches will do anything, but inexpensive ones like TP-Link, D-Link or Netgear will only do it in certain topologies? And will basic VLAN support be good enough for this topology? I guess even cheap managed switches can tag traffic from each port with it’s own VLAN tag, but when the next switch in the daisy chain receives the packet on it’s “downlink” port, wouldn’t it strip or replace the VLAN tag with it’s own trunk-tag (or whatever the name is for the backbone traffic). Money is tight, and I don’t think we can afford professional grade Cisco (I have been campaigning for this for years), so I’d love some advice on which solution has the best support on low-end network equipment and if there are some specific models that are recommended? For instance low-end HP switches or even budget brands like TP-Link, D-Link etc. If I have overlooked another way to solve this problem it is due to my lack of knowledge. :)

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  • Persuading openldap to work with SSL on Ubuntu with cn=config

    - by Roger
    I simply cannot get this (TLS connection to openldap) to work and would appreciate some assistance. I have a working openldap server on ubuntu 10.04 LTS, it is configured to use cn=config and most of the info I can find for TLS seems to use the older slapd.conf file :-( I've been largely following the instructions here https://help.ubuntu.com/10.04/serverguide/C/openldap-server.html plus stuff I've read here and elsewhere - which of course could be part of the problem as I don't totally understand all of this yet! I have created an ssl.ldif file as follows; dn:cn=config add: olcTLSCipherSuite olcTLSCipherSuite: TLSV1+RSA:!NULL add: olcTLSCRLCheck olcTLSCRLCheck: none add: olcTLSVerifyClient olcTLSVerifyClient: never add: olcTLSCACertificateFile olcTLSCACertificateFile: /etc/ssl/certs/ldap_cacert.pem add: olcTLSCertificateFile olcTLSCertificateFile: /etc/ssl/certs/my.domain.com_slapd_cert.pem add: olcTLSCertificateKeyFile olcTLSCertificateKeyFile: /etc/ssl/private/my.domain.com_slapd_key.pem and I import it using the following command line ldapmodify -x -D cn=admin,dc=mydomain,dc=com -W -f ssl.ldif I have edited /etc/default/slapd so that it has the following services line; SLAPD_SERVICES="ldap:/// ldapi:/// ldaps:///" And everytime I'm making a change, I'm restarting slapd with /etc/init.d/slapd restart The following command line to test out the non TLS connection works fine; ldapsearch -d 9 -D cn=admin,dc=mydomain,dc=com -w mypassword \ -b dc=mydomain,dc=com -H "ldap://mydomain.com" "cn=roger*" But when I switch to ldaps using this command line; ldapsearch -d 9 -D cn=admin,dc=mydomain,dc=com -w mypassword \ -b dc=mydomain,dc=com -H "ldaps://mydomain.com" "cn=roger*" This is what I get; ldap_url_parse_ext(ldaps://mydomain.com) ldap_create ldap_url_parse_ext(ldaps://mydomain.com:636/??base) ldap_sasl_bind ldap_send_initial_request ldap_new_connection 1 1 0 ldap_int_open_connection ldap_connect_to_host: TCP mydomain.com:636 ldap_new_socket: 3 ldap_prepare_socket: 3 ldap_connect_to_host: Trying 127.0.0.1:636 ldap_pvt_connect: fd: 3 tm: -1 async: 0 TLS: can't connect: A TLS packet with unexpected length was received.. ldap_err2string ldap_sasl_bind(SIMPLE): Can't contact LDAP server (-1) Now if I check netstat -al I can see; tcp 0 0 *:www *:* LISTEN tcp 0 0 *:ssh *:* LISTEN tcp 0 0 *:https *:* LISTEN tcp 0 0 *:ldaps *:* LISTEN tcp 0 0 *:ldap *:* LISTEN I'm not sure if this is significant as well ... I suspect it is; openssl s_client -connect mydomain.com:636 -showcerts CONNECTED(00000003) 916:error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure:s23_lib.c:188: I think I've made all my certificates etc OK and here are the results of some checks; If I do this; certtool -e --infile /etc/ssl/certs/ldap_cacert.pem I get Chain verification output: Verified. certtool -e --infile /etc/ssl/certs/mydomain.com_slapd_cert.pem Gives "certtool: the last certificate is not self signed" but it otherwise seems OK? Where have I gone wrong? Surely getting openldap to run securely on ubuntu should be easy and not require a degree in rocket science! Any ideas?

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  • Tutorial for configuring OpenVPN [on hold]

    - by user2699451
    I have been through 10+ tutorials on setting up a OpenVPN, and each tutorial gives a different problem... Does anyone know of a decent and helpful website/tutorial which I could go to to get it set up? I have been battling through it for almost 2 months now. Yes, I have also bugged forums.openvpn, but I think I have "reached my post limit" with them. I have to configure it remotely via ssh. UPDATE: okay, I have been asked to be more clear on the topic I followed this tutorial (as a example) - http://www.servermom.com/how-to-build-openvpn-server-on-centos-6-x/732/ I had no issues setting up, etc. except when I boot into windows and run the OpenVPN GUI Client, it connects and gives this error: WARNING: Bad encapsulated packet length from peer (21331), which must be 0 and <= 1576 -- please ensure that --tun-mtu or --link-mtu is equal on both peers -- this condition could also indicate a possible active attack on the TCP link -- [Attemping restart...] Here is my server config: port 1194 #- port proto udp #- protocol dev tun tun-mtu 1500 tun-mtu-extra 32 mssfix 1450 reneg-sec 0 ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt cert /etc/openvpn/easy-rsa/2.0/keys/server.crt key /etc/openvpn/easy-rsa/2.0/keys/server.key dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem plugin /usr/lib64/openvpn/plugin/lib/openvpn-auth-pam.so /etc/pam.d/login #- Co$ #plugin /etc/openvpn/radiusplugin.so /etc/openvpn/radiusplugin.cnf #- Uncomment$ client-cert-not-required username-as-common-name server 10.8.0.0 255.255.255.0 push "redirect-gateway def1" push "dhcp-option DNS 8.8.8.8" push "dhcp-option DNS 8.8.4.4" keepalive 5 30 comp-lzo persist-key persist-tun status 1194.log verb 3 and my client config: client dev tun proto udp remote [server ip] 1194 # - Your server IP and OpenVPN Port resolv-retry infinite nobind tun-mtu 1500 tun-mtu-extra 32 mssfix 1450 persist-key persist-tun ca ca.crt auth-user-pass comp-lzo reneg-sec 0 verb 3 OpenVPN Client Log: Thu Oct 31 11:51:29 2013 OpenVPN 2.0.9 Win32-MinGW [SSL] [LZO] built on Oct 1 2006 Thu Oct 31 11:51:44 2013 IMPORTANT: OpenVPN's default port number is now 1194, based on an official port number assignment by IANA. OpenVPN 2.0-beta16 and earlier used 5000 as the default port. Thu Oct 31 11:51:44 2013 WARNING: No server certificate verification method has been enabled. See http://openvpn.net/howto.html#mitm for more info. Thu Oct 31 11:51:44 2013 LZO compression initialized Thu Oct 31 11:51:44 2013 Control Channel MTU parms [ L:1576 D:140 EF:40 EB:0 ET:0 EL:0 ] Thu Oct 31 11:51:44 2013 Data Channel MTU parms [ L:1576 D:1450 EF:44 EB:135 ET:32 EL:0 AF:3/1 ] Thu Oct 31 11:51:44 2013 Local Options hash (VER=V4): '2547efd2' Thu Oct 31 11:51:44 2013 Expected Remote Options hash (VER=V4): '77cf0943' Thu Oct 31 11:51:44 2013 Attempting to establish TCP connection with x.x.x.x:1194 Thu Oct 31 11:51:44 2013 TCP connection established with x.x.x.x:1194 Thu Oct 31 11:51:44 2013 TCPv4_CLIENT link local: [undef] Thu Oct 31 11:51:44 2013 TCPv4_CLIENT link remote: x.x.x.x:1194 // after this it just hangs, nothing happens So I dont know what I am doing wrong but I am getting a bit impatient and on each forum I post this, I get stupid/unrelated/unhelpful answers...

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  • Block IP Address including ICMP using UFW

    - by dr jimbob
    I prefer ufw to iptables for configuring my software firewall. After reading about this vulnerability also on askubuntu, I decided to block the fixed IP of the control server: 212.7.208.65. I don't think I'm vulnerable to this particular worm (and understand the IP could easily change), but wanted to answer this particular comment about how you would configure a firewall to block it. I planned on using: # sudo ufw deny to 212.7.208.65 # sudo ufw deny from 212.7.208.65 However as a test that the rules were working, I tried pinging after I setup the rules and saw that my default ufw settings let ICMP through even from an IP address set to REJECT or DENY. # ping 212.7.208.65 PING 212.7.208.65 (212.7.208.65) 56(84) bytes of data. 64 bytes from 212.7.208.65: icmp_seq=1 ttl=52 time=79.6 ms ^C --- 212.7.208.65 ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 79.630/79.630/79.630/0.000 ms Now, I'm worried that my ICMP settings are too generous (conceivably this or a future worm could setup an ICMP tunnel to bypass my firewall rules). I believe this is the relevant part of my iptables rules is given below (and even though grep doesn't show it; the rules are associated with the chains shown): # sudo iptables -L -n | grep -E '(INPUT|user-input|before-input|icmp |212.7.208.65)' Chain INPUT (policy DROP) ufw-before-input all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-before-input (1 references) ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 3 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 4 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 11 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 12 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 8 ufw-user-input all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-user-input (1 references) DROP all -- 0.0.0.0/0 212.7.208.65 DROP all -- 212.7.208.65 0.0.0.0/0 How should I go about making it so ufw blocks ICMP when I specifically attempt to block an IP address? My /etc/ufw/before.rules has in part: # ok icmp codes -A ufw-before-input -p icmp --icmp-type destination-unreachable -j ACCEPT -A ufw-before-input -p icmp --icmp-type source-quench -j ACCEPT -A ufw-before-input -p icmp --icmp-type time-exceeded -j ACCEPT -A ufw-before-input -p icmp --icmp-type parameter-problem -j ACCEPT -A ufw-before-input -p icmp --icmp-type echo-request -j ACCEPT I'm tried changing ACCEPT above to ufw-user-input: # ok icmp codes -A ufw-before-input -p icmp --icmp-type destination-unreachable -j ufw-user-input -A ufw-before-input -p icmp --icmp-type source-quench -j ufw-user-input -A ufw-before-input -p icmp --icmp-type time-exceeded -j ufw-user-input -A ufw-before-input -p icmp --icmp-type parameter-problem -j ufw-user-input -A ufw-before-input -p icmp --icmp-type echo-request -j ufw-user-input But ufw wouldn't restart after that. I'm not sure why (still troubleshooting) and also not sure if this is sensible? Will there be any negative effects (besides forcing the software firewall to force ICMP through a few more rules)?

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  • Malware - Technical anlaysis

    - by nullptr
    Note: Please do not mod down or close. Im not a stupid PC user asking to fix my pc problem. I am intrigued and am having a deep technical look at whats going on. I have come across a Windows XP machine that is sending unwanted p2p traffic. I have done a 'netstat -b' command and explorer.exe is sending out the traffic. When I kill this process the traffic stops and obviously Windows Explorer dies. Here is the header of the stream from the Wireshark dump (x.x.x.x) is the machines IP. GNUTELLA CONNECT/0.6 Listen-IP: x.x.x.x:8059 Remote-IP: 76.164.224.103 User-Agent: LimeWire/5.3.6 X-Requeries: false X-Ultrapeer: True X-Degree: 32 X-Query-Routing: 0.1 X-Ultrapeer-Query-Routing: 0.1 X-Max-TTL: 3 X-Dynamic-Querying: 0.1 X-Locale-Pref: en GGEP: 0.5 Bye-Packet: 0.1 GNUTELLA/0.6 200 OK Pong-Caching: 0.1 X-Ultrapeer-Needed: false Accept-Encoding: deflate X-Requeries: false X-Locale-Pref: en X-Guess: 0.1 X-Max-TTL: 3 Vendor-Message: 0.2 X-Ultrapeer-Query-Routing: 0.1 X-Query-Routing: 0.1 Listen-IP: 76.164.224.103:15649 X-Ext-Probes: 0.1 Remote-IP: x.x.x.x GGEP: 0.5 X-Dynamic-Querying: 0.1 X-Degree: 32 User-Agent: LimeWire/4.18.7 X-Ultrapeer: True X-Try-Ultrapeers: 121.54.32.36:3279,173.19.233.80:3714,65.182.97.15:5807,115.147.231.81:9751,72.134.30.181:15810,71.59.97.180:24295,74.76.84.250:25497,96.234.62.221:32344,69.44.246.38:42254,98.199.75.23:51230 GNUTELLA/0.6 200 OK So it seems that the malware has hooked into explorer.exe and hidden its self quite well as a Norton Scan doesn't pick anything up. I have looked in Windows firewall and it shouldn't be letting this traffic through. I have had a look into the messages explorer.exe is sending in Spy++ and the only related ones I can see are socket connections etc... My question is what can I do to look into this deeper? What does malware achieve by sending p2p traffic? I know to fix the problem the easiest way is to reinstall Windows but I want to get to the bottom of it first, just out of interest. Edit: Had a look at Deoendency Walker and Process Explorer. Both great tools. Here is a image of the TCP connections for explorer.exe in Process Explorer http://img210.imageshack.us/img210/3563/61930284.gif

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  • Starting/Stopping Custom PHP Chat Server Linux Service (CentOS)

    - by chad
    I have been trying all night to get this service working properly. I created this script from a template and am very new to bash coding. I wrote a fully functioning chat server in php which runs endlessly, but now want to make it a dedicated service. I want to do this so that it starts on server boot and boots back up if possible when there are any down-times with the server. The issue is that I need this thing to run in a detached screen so that I can monitor packet data or send server commands via SSH when need-be. The main problem that i'm having is that it needs to have its own PID when it starts so that I can stop/restart it when needed. I am the type who grinds on coding until I figure it out, but this is so new to me that it seems the learning curve here is very steep and frustrating. Below is my code if anybody can please help me with this one, i've gotten so tired I can't even concentrate any more :( #!/bin/sh # # chatserver # # chkconfig: 345 20 90 # description: chatServer Linux Service Daemon \ # for general server handling ### BEGIN INIT INFO # Provides: chatserver # Required-Start: $local_fs $network $named $syslog # Required-Stop: $local_fs $syslog # Default-Start: 3 4 5 # Default-Stop: 0 1 2 6 # Short-Description: This service maintains the chatServer # Description: chatServer Linux Service Daemon # for general server handling ### END INIT INFO # Source function library. . /etc/rc.d/init.d/functions exec="screen php -q /var/www/html/chatServer.php" prog="chatserver" config="/etc/sysconfig/$prog" pidfile="/var/run/chatserver.pid" [ -e /etc/sysconfig/$prog ] && . /etc/sysconfig/$prog lockfile=/var/lock/subsys/$prog start() { #$exec || exit 5 echo -n $"Starting $prog: " daemon $exec --name=$exec --pidfile=$pidfile retval=$? echo [ $retval -eq 0 ] && touch $lockfile return $retval } stop() { echo -n $"Stopping $prog: " killproc -p $pidfile rm -f $pidfile retval=$? echo [ $retval -eq 0 ] && rm -f $lockfile return $retval } restart() { stop start } reload() { restart } force_reload() { restart } rh_status() { # run checks to determine if the service is running or use generic status status $prog } rh_status_q() { rh_status >/dev/null 2>&1 } case "$1" in start) rh_status_q && exit 0 $1 ;; stop) rh_status_q || exit 0 $1 ;; restart) $1 ;; reload) rh_status_q || exit 7 $1 ;; force-reload) force_reload ;; status) rh_status ;; condrestart|try-restart) rh_status_q || exit 0 restart ;; *) echo $"Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-reload}" exit 2 esac exit $?

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  • ubuntu eth0 not reconnecting after cable unplugged

    - by Alex
    I'm running kubuntu 9.10 w/ gnome, I have a static IP defined in /etc/network/interfaces When I unplugged my network cable and rebooted, then reconnected the network cable I was not able to connect. I tried using sudo ifup eth0, and then ifconfig and it seemed as though the IP address had been assigned and I was connected, but I wasn't. I then did ifdown eth0, and again ifup eth0. For some reason I'm not able to access the network. Furthermore, I also attempted to connect via wlan, and was able to connect to the wireless network, but cannot "see" the network. I can't transfer data or access the internet or anything on the network including the router. How do I resolve this? topsy@monolyth:~$ ifconfig eth0 Link encap:Ethernet HWaddr 00:1c:25:1c:df:70 inet addr:192.168.1.145 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::21c:25ff:fe1c:df70/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5720 errors:0 dropped:0 overruns:0 frame:0 TX packets:565 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:378035 (378.0 KB) TX bytes:46832 (46.8 KB) Memory:fe000000-fe020000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:4 errors:0 dropped:0 overruns:0 frame:0 TX packets:4 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:240 (240.0 B) TX bytes:240 (240.0 B) By access the network I mean the local network as well as the internet. topsy@monolyth:~$ ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=9.14 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=1.24 ms 64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=1.01 ms 64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=1.00 ms [snip... all OK, icmp_seq from 5-30, time between 0.981-1.25ms] ^C --- 192.168.1.1 ping statistics --- 30 packets transmitted, 30 received, 0% packet loss, time 29035ms rtt min/avg/max/mdev = 0.971/1.300/9.140/1.458 ms topsy@monolyth:~$ route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 * 255.255.255.0 U 0 0 0 eth0 link-local * 255.255.0.0 U 1000 0 0 eth0 default 192.168.1.1 0.0.0.0 UG 100 0 0 eth0 root@monolyth:~# cat /etc/resolv.conf # Generated by NetworkManager

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  • Tomcat can't talk to MySql after outage

    - by gav
    I missed a payment for my server and hey suspended my account for a day or so. When they brought the server back up all my data was in tact but for some reason Tomcat can't make a JDBC connection to my MySql server. They both run on the same machine and hence I have a bind address of 127.0.0.1. It's strange because I have reset the machine of my own accord before without issue but clearly something has been reset in the downtime. I followed this guide (Just the bits which don't concern S3, I am not on Amazon infrastructure) originally and everything worked as expected. I'm very new to being a SysAdmin and I'm not sure what to try, how would you go about diagnosing this issue? The stack trace I get is as follows; INFO: Deploying web application archive myapp-1.1.war 2010-05-26 22:07:22,221 [main] ERROR context.ContextLoader - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'messageSource': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Cannot resolve reference to bean 'hibernateProperties' while setting bean property 'hibernateProperties'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Could not get Connection for extracting meta data; nested exception is org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) at org.codehaus.groovy.grails.commons.spring.ReloadAwareAutowireCapableBeanFactory.doCreateBean(ReloadAwareAutowireCapableBeanFactory.java:129) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:450) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:290) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:287) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) at org.springframework.context.support.AbstractApplicationContext.initMessageSource(AbstractApplicationContext.java:714) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:404) at org.codehaus.groovy.grails.commons.spring.GrailsWebApplicationContext.refresh(GrailsWebApplicationContext.java:153) ... I get this error for a number of 'beans'. If I type mysql at my command prompt then I can easily login with the same credentials as my grails app which uses GORM and Hibernate to persist objects to the DB. I might not have given enough info to start with but I'm really interested to learn and will certainly provide it if asked, I just really don't know where to start on this one. Thanks, Gav

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  • Link aggregation with freebsd8 and a cicso 3550, what am i doing wrong?

    - by Flamewires
    Hey, I am trying to setup Link Aggrigation with LACP (well, anything that provides increased bandwidth and failover using my setup will work). I'm running FreeBSD 8.0 on 3 machines. M1 is running 2 10/100 ethernetcards setup for link aggrigation using lagg. for reference: ifconfig em0 up ifconfig tx0 up ifconfig create lagg0 ifconfig lagg0 laggproto lacp laggport tx0 laggport em0 192.168.1.16 netmask 255.255.255.0 I plugged them into ports 1 and 2 of a Cicso 3550. then ran: configure terminal interface range Fa0/1 - 2 switchport mode access switchport access vlan 1 channel-group 1 mode active (everythings in vlan 1) Now Im able to connect the other computers to other ports on the switch and failover works great, i can unplug cables in the middle of a transfer and the traffic gets rerouted. However, im not noticing any speed increase. My test setup: load balancing: i tried dst and src on the switch, neither seemed to give me a speed increase. I am SCPing 2 500 meg files from the lagg computer to other computers (one each) which are also running 10/100 full duplex cards. I get transfer speeds of about 11.2-11.4 Mbps to a single host, and about half that (5.9-6.2) Mbps when transferring to both at the same time. From what I understood with destination load balancing the router was suppose to balance traffic headed for 1 computer over 1 port and traffic headed for another over a diff(in this case) the other port. With destination-MAC address forwarding, when packets are forwarded to an EtherChannel, the packets are distributed across the ports in the channel based on the destination host MAC address of the incoming packet. Therefore, packets to the same destination are forwarded over the same port, and packets to a different destination are sent on a different port in the channel. For the 3550 series switch, when source-MAC address forwarding is used, load distribution based on the source and destination IP address is also enabled for routed IP traffic. All routed IP traffic chooses a port based on the source and destination IP address. Packets between two IP hosts always use the same port in the channel, and traffic between any other pair of hosts can use a different port in the channel. (Link) What am i doing wrong/what would i need to do to see a speed increase beyond what i could do with just a single card?

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  • Solution to route/proxy SNMP Traps (or Netflow, generic UDP, etc) for network monitoring?

    - by Christopher Cashell
    I'm implementing a network monitoring solution for a very large network (approximately 5000 network devices). We'd like to have all devices on our network send SNMP traps to a single box (technically this will probably be an HA pair of boxes) and then have that box pass the SNMP traps on to the real processing boxes. This will allow us to have multiple back-end boxes handling traps, and to distribute load among those back end boxes. One key feature that we need is the ability to forward the traps to a specific box depending on the source address of the trap. Any suggestions for the best way to handle this? Among the things we've considered are: Using snmptrapd to accept the traps, and have it pass them off to a custom written perl handler script to rewrite the trap and send it to the proper processing box Using some sort of load balancing software running on a Linux box to handle this (having some difficulty finding many load balancing programs that will handle UDP) Using a Load Balancing Appliance (F5, etc) Using IPTables on a Linux box to route the SNMP traps with NATing We've currently implemented and are testing the last solution, with a Linux box with IPTables configured to receive the traps, and then depending on the source address of the trap, rewrite it with a destination nat (DNAT) so the packet gets sent to the proper server. For example: # Range: 10.0.0.0/19 Site: abc01 Destination: foo01 iptables -t nat -A PREROUTING -p udp --dport 162 -s 10.0.0.0/19 -j DNAT --to-destination 10.1.2.3 # Range: 10.0.33.0/21 Site: abc01 Destination: foo01 iptables -t nat -A PREROUTING -p udp --dport 162 -s 10.0.33.0/21 -j DNAT --to-destination 10.1.2.3 # Range: 10.1.0.0/16 Site: xyz01 Destination: bar01 iptables -t nat -A PREROUTING -p udp --dport 162 -s 10.1.0.0/16 -j DNAT --to-destination 10.3.2.1 This should work with excellent efficiency for basic trap routing, but it leaves us completely limited to what we can mach and filter on with IPTables, so we're concerned about flexibility for the future. Another feature that we'd really like, but isn't quite a "must have" is the ability to duplicate or mirror the UDP packets. Being able to take one incoming trap and route it to multiple destinations would be very useful. Has anyone tried any of the possible solutions above for SNMP traps (or Netflow, general UDP, etc) load balancing? Or can anyone think of any other alternatives to solve this?

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  • Planning trunk capacity for multiple GbE switches

    - by wuckachucka
    Without measuring throughput (it's at the top of the list; this is just theoretical), I want to know the most standard method for trunking VLANs on multiple Gigabit (GbE) switches to a core Layer 3 GbE switch. Say you have three VLANs: VLAN10 (10.0.0.0/24) Servers: your typical Windows DC/file server, Exchange, and an Accounting/SQL server. VLAN20: (10.0.1.0/24) Sales: needs access to everything on VLAN10; doesn't need access to VLAN30 and vice-versa. VLAN20: (10.0.1.0/24) Support: needs access to everything on VLAN10; doesn't need access to VLAN20 and vice-versa. Here's how I think this should work in my head: Switch #1: Ports 2-20 are assigned to VLAN20; all the Sales workstations and printers are connected here. Optional 10GbE combo port #1 is trunked to L3 switch's 10 GbE combo port #1. Switch #2: Ports 2-20 are assigned to VLAN30; all the Support workstations and printers are connected here. Optional 10GbE combo port #1 is trunked to L3 switch's 10 GbE combo port #2. Core L3 switch: Ports 2-10 are assigned to VLAN10; all three servers are connected here. With a standard 10/100 x 24 switch, it'll usually come with one or two 1 GbE uplink ports; carrying over this logic to a 10/100/1000 x 24, the "optional" 10 GbE combo ports that most higher-end switches can get shouldn't really be an option. Keep in mind I haven't tested anything yet, I'm primarily moving in this direction for growth (don't want to buy 10/100 switches and have to replace those within a couple of years) and security (being able to control access between VLANs with L3 routing/packet filtering ACLs). Does this sound right? Do I really need the 10 GbE ports? It seems very non-standard and expensive, but it "feels" right when you think about 40 or 50 workstations trunking up to the L3 switch over 1 GbE standard ports. If say 20 workstations want to download a 10 GB image from the servers concurrently, wouldn't the trunk be the bottleneck? At least if the trunk was 10 GbE, you'd have 10x1GbE nodes being able to reach their theoretical max. What about switch stacking? Some of the D-Links I've been looking at have HDMI interfaces for stacking. As far as I know, stacking two switches creates one logical switch, but is this just for management I/O or does the switches use the (assuming it's HDMI 1.3) 10.2 Gbps for carrying data back and forth?

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  • Forwarding RDP via a Linux machine using iptables: Not working

    - by Nimmy Lebby
    I have a Linux machine and a Windows machine behind a router that implements NAT (the diagram might be overkill, but was fun to make): I am forwarding RDP port (3389) on the router to the Linux machine because I want to audit RDP connections. For the Linux machine to forward RDP traffic, I wrote these iptables rules: iptables -t nat -A PREROUTING -p tcp --dport 3389 -j DNAT --to-destination win-box iptables -A FORWARD -p tcp --dport 3389 -j ACCEPT The port is listening on the Windows machine: C:\Users\nimmy>netstat -a Active Connections Proto Local Address Foreign Address State (..snip..) TCP 0.0.0.0:3389 WIN-BOX:0 LISTENING (..snip..) And the port is forwarding on the Linux machine: # tcpdump port 3389 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 01:33:11.451663 IP shieldsup.grc.com.56387 > linux-box.myapt.lan.ms-wbt-server: Flags [S], seq 94663035, win 8192, options [mss 1460], length 0 01:33:11.451846 IP shieldsup.grc.com.56387 > win-box.myapt.lan.ms-wbt-server: Flags [S], seq 94663035, win 8192, options [mss 1460], length 0 However, I am not getting any successful RDP connections from the outside. The port is not even responding: C:\Users\outside-nimmy>telnet example.com 3389 Connecting To example.com...Could not open connection to the host, on port 3389: Connect failed Any ideas? Update Per @Zhiqiang Ma, I looked at nf_conntrack proc file during a connection attempt and this is what I see (192.168.3.1 = linux-box, 192.168.3.5 = win-box): # cat /proc/net/nf_conntrack | grep 3389 ipv4 2 tcp 6 118 SYN_SENT src=4.79.142.206 dst=192.168.3.1 sport=43142 dport=3389 packets=6 bytes=264 [UNREPLIED] src=192.168.3.5 dst=4.79.142.206 sport=3389 dport=43142 packets=0 bytes=0 mark=0 secmark=0 zone=0 use=2 2nd update Got tcpdump on the router and it seems that win-box is sending an RST packet: 21:20:24.767792 IP shieldsup.grc.com.45349 > linux-box.myapt.lan.3389: S 19088743:19088743(0) win 8192 <mss 1460> 21:20:24.768038 IP shieldsup.grc.com.45349 > win-box.myapt.lan.3389: S 19088743:19088743(0) win 8192 <mss 1460> 21:20:24.770674 IP win-box.myapt.lan.3389 > shieldsup.grc.com.45349: R 721745706:721745706(0) ack 755785049 win 0 Why would Windows be doing this?

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  • "Hostile" network in the company - please comment on a security setup

    - by TomTom
    I have a little specific problem here that I want (need) to solve in a satisfactory way. My company has multiple (IPv4) networks that are controlled by our router sitting in the middle. Typical smaller shop setup. There is now one additional network that has an IP Range OUTSIDE of our control, connected to the internet with another router OUTSIDE of our control. Call it a project network that is part of another companies network and combined via VPN they set up. This means: They control the router that is used for this network and They can reconfigure things so that they can access the machines in this network. The network is physically split on our end through some VLAN capable switches as it covers three locations. At one end there is the router the other company controls. I Need / want to give the machines used in this network access to my company network. In fact, it may be good to make them part of my active directory domain. The people working on those machines are part of my company. BUT - I need to do so without compromising the security of my company network from outside influence. Any sort of router integration using the externally controlled router is out by this idea So, my idea is this: We accept the IPv4 address space and network topology in this network is not under our control. We seek alternatives to integrate those machines into our company network. The 2 concepts I came up with are: Use some sort of VPN - have the machines log into VPN. Thanks to them using modern windows, this could be transparent DirectAccess. This essentially treats the other IP space not different than any restaurant network a laptop of the company goes in. Alternatively - establish IPv6 routing to this ethernet segment. But - and this is a trick - block all IPv6 packets in the switch before they hit the third party controlled router, so that even IF they turn on IPv6 on that thing (not used now, but they could do it) they would get not a single packet. The switch can nicely do that by pulling all IPv6 traffic coming to that port into a separate VLAN (based on ethernet protocol type). Anyone sees a problem with using he switch to isolate the outer from IPv6? Any security hole? It is sad we have to treat this network as hostile - would be a lot easier - but the support personnel there is of "known dubious quality" and the legal side is clear - we can not fulfill our obligations when we integrate them into our company while they are under a jurisdiction we don't have a say in.

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  • Wake On Lan only works on first boot, not sequent ones

    - by sp3ctum
    I have converted my old Dell Latitude D410 laptop to a server for tinkering. It is running an updated Debian Squeeze (6) with a Xen enabled kernel (I want to toy with virtual machines later on). I am running it 'headless' via an ethernet connection. I am struggling to enable Wake On Lan for the box. I have enabled the setting in the BIOS, and it works nicely, but only for the first time after the power cord is plugged in. Here is my test: Plug in power cord, don't boot yet Send magic Wake On Lan packet from test machine (Ubuntu) using the wakeonlan program Server expected to start (does every time) Once server has booted, log in via ssh and shut it down via the operating system After shutdown, wake server up via WOL again (fails every time) Some observations: Right after step 1 I can see the integrated NIC has a light on. I deduce this means the NIC gets adequate power and that the ethernet cable is connected to my switch. This light is not on after step 4 (the shutdown stage). The light becomes back on after I disconnect and reconnect the power cord, after which WOL works as well. After step 4 I can verify that wake on lan is enabled via the ethtool program (repeatable each time) This blog post suggested the problem may lay in the fact the motherboard might not be giving adequate power to the NIC after shutdown, so I copied an acpitool script that supposedly should signal the system to give the needed power to the card when shut down. Obviously it did not fix my issue. I have included the relevant power settings in the paste below. I have tried different combinations of parameters of shutdown (the program) options, as well as the poweroff program. I even tried "telinit 0", which I figured would do the most direct boot via software. If I keep the laptop's power button pressed down and do a hard boot this way, the light on the ethernet port stays lit and a WOL is possible. I copied a bunch of hopefully useful information in this paste I have tried this with the laptop battery connected and without it. I get the same result. Promptly pressing the power button causes the system to shut down with the message "The system is going down for system halt NOW!", and WOL is still unsuccessful.

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  • Too many TIME_WAIT state connections!

    - by Hamza
    I've been reading about this everywhere all day, and from what I've gathered, TIME_WAIT is a relatively harmless state. It's supposed to be harmless even when there's too many. But if they're jumping to the numbers I've been seeing for the past 24 hours, something is really wrong! [root@1 ~]# netstat -nat | awk '{print $6}' | sort | uniq -c | sort -n 1 established) 1 Foreign 12 CLOSE_WAIT 15 LISTEN 64 LAST_ACK 201 FIN_WAIT2 334 CLOSING 605 ESTABLISHED 816 SYN_RECV 981 FIN_WAIT1 26830 TIME_WAIT That number fluctuates from 20,000 to 30,000+ (so far, the maximum I've seen it go is 32,000). What worries me is that they're all different IP addresses from all sorts of random locations. Now this is supposed to be (or was supposed to be) a DDoS attack. I know this for a fact, but I won't go into the boring details. It started out as a DDoS and it did impact my server's performance for a couple minutes. After that, everything was back to normal. My server load is normal. My internet traffic is normal. No server resource is being abused. My sites load fine. I also have IPTABLES disabled. There's an odd issue with that too. Every time I enable the firewall/iptables, my server starts experiencing packet loss. Lots of it. About 50%-60% packets are lost. It happens within an hour or within a few hours of enabling the firewall. As soon as I disable it, ping responses from all locations I test them from start clearing up and get stable again. Very strange. The TIME_WAIT state connections have been fluctuating at those numbers since yesterday. For 24 hours now, I've had that, and although it hasn't impacted performance in any way, it's disturbing enough. My current tcp_fin_timeout value is 30 seconds, from the default 60 seconds. However, that seems to not help, at all. Any ideas, suggestions? Anything at all would be appreciated, really!

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  • Problem connecting to SSH in office network

    - by Jeune
    I have trouble connecting via SSH to a server whenever I am in the office. I get as far as being prompted for my password and then after that there's a long wait which always ends in a Write failed: Broken pipe This is only for connecting via SSH. I use svn to commit files to a repository hosted on the same server and there are no hitches. Furthermore, this only happens in our office. When I go the university or whenever I am at home or at the coffee shop I am able to connect seamlessly. There are no firewalls in our office. It's just a basic wireless router connected to a modem setup. It's the same setup I have at home and I guess the same setup in the coffee shop. What are the causes for a broken pipe and why does this phenomenon only happen when I try connect via SSH and not when I work with svn on the same server? Updated: Some debug logs after authentication: debug3: packet_send2: adding 48 (len 64 padlen 16 extra_pad 64) debug2: we sent a password packet, wait for reply debug1: Authentication succeeded (password). debug1: channel 0: new [client-session] debug3: ssh_session2_open: channel_new: 0 debug2: channel 0: send open debug1: Entering interactive session. debug2: callback start debug2: client_session2_setup: id 0 debug2: channel 0: request pty-req confirm 1 debug1: Sending environment. debug3: Ignored env ORBIT_SOCKETDIR debug3: Ignored env SSH_AGENT_PID debug3: Ignored env TERM debug3: Ignored env SHELL debug3: Ignored env XDG_SESSION_COOKIE debug3: Ignored env WINDOWID debug3: Ignored env GNOME_KEYRING_CONTROL debug3: Ignored env GTK_MODULES debug3: Ignored env USER debug3: Ignored env LS_COLORS debug3: Ignored env LIBGL_DRIVERS_PATH debug3: Ignored env SSH_AUTH_SOCK debug3: Ignored env DEFAULTS_PATH debug3: Ignored env SESSION_MANAGER debug3: Ignored env USERNAME debug3: Ignored env XDG_CONFIG_DIRS debug3: Ignored env DESKTOP_SESSION debug3: Ignored env LIBGL_ALWAYS_INDIRECT debug3: Ignored env PATH debug3: Ignored env PWD debug3: Ignored env GDM_KEYBOARD_LAYOUT debug1: Sending env LANG = en_PH.utf8 debug2: channel 0: request env confirm 0 debug3: Ignored env GNOME_KEYRING_PID debug3: Ignored env MANDATORY_PATH debug3: Ignored env GDM_LANG debug3: Ignored env GDMSESSION debug3: Ignored env SHLVL debug3: Ignored env HOME debug3: Ignored env GNOME_DESKTOP_SESSION_ID debug3: Ignored env LOGNAME debug3: Ignored env XDG_DATA_DIRS debug3: Ignored env DBUS_SESSION_BUS_ADDRESS debug3: Ignored env LESSOPEN debug3: Ignored env WINDOWPATH debug3: Ignored env DISPLAY debug3: Ignored env LESSCLOSE debug3: Ignored env XAUTHORITY debug3: Ignored env COLORTERM debug3: Ignored env OLDPWD debug3: Ignored env _ debug2: channel 0: request shell confirm 1 debug2: fd 3 setting TCP_NODELAY debug2: callback done debug2: channel 0: open confirm rwindow 0 rmax 32768 UPDATE 2011-14-07: I am able to connect to the server via SSH now. I didn't do anything but that's because there is no one in the office but me! Having said that, is it possible that it has something to do with the number of sessions an SSH server can handle? UPDATE 2011-14-07: I try to login via SSH through Putty on another machine running windows together with my current SSH session in Ubuntu and now it seems my SSH session in Ubuntu has been dropped. I can't type into the terminal. Is Putty the culprit now?

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  • No Telnet login prompt when used over SSH tunnel

    - by SCO
    Hi there ! I have a device, let's call it d1, runnning a lightweight Linux. This device is NATed by my internet box/router, hence not reachable from the Internet. That device runs a telnet daemon on it, and only has root as user (no pwd). Its ip address is 192.168.0.126 on the private network. From the private network (let's say 192.168.0.x), I can do: telnet 192.168.0.126 Where 192.168.0.126 is the IP address in the private network. This works correctly. However, to allow administration, I'd need to access that device from outside of that private network. Hence, I created an SSH tunnel like this on d1 : ssh -R 4455:localhost:23 ussh@s1 s1 is a server somewhere in the private network (but this is for testing purposes only, it will endup somewhere in the Internet), running a standard Linux distro and on which I created a user called 'ussh'. s1 IP address is 192.168.0.48. When I 'telnet' with the following, let's say from c1, 192.168.0.19 : telnet -l root s1 4455 I get : Trying 192.168.0.48... Connected to 192.168.0.48. Escape character is '^]'. Connection closed by foreign host . The connection is closed after roughly 30 seconds, and I didn't log. I tried without the -l switch, without any success. I tried to 'telnet' with IP addresses instead of names to avoid reverse DNS issues (although I added to d1 /etc/hosts a line refering to s1 IP/name, just in case), no success. I tried on another port than 4455, no success. I gathered Wireshark logs from s1. I can see : s1 sends SSH data to c1, c1 ACK s1 performs an AAAA DNS request for c1, gets only the Authoritave nameservers. s1 performs an A DNS request, then gets c1's IP address s1 sends a SYN packet to c1, c1 replies with a RST/ACK s1 sends a SYN to c1, C1 RST/ACK (?) After 0.8 seconds, c1 sends a SYN to s1, s1 SYN/ACK and then c1 ACK s1 sends SSH content to d1, d1 sends an ACK back to s1 s1 retries AAAA and A DNS requests After 5 seconds, s1 retries a SYN to c1, once again it is RST/ACKed by c1. This is repeated 3 more times. The last five packets : d1 sends SSH content to s1, s1 sends ACK and FIN/ACK to c1, c1 replies with FIN/ACK, s1 sends ACK to c1. The connection seems to be closed by the telnet daemon after 22 seconds. AFAIK, there is no way to decode the SSH stream, so I'm really stuck here ... Any ideas ? Thank you !

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  • udp expected behaviour not responding to test result

    - by ernst
    I have a local network topology that is structured as follows: three hosts and a switch in the middle. I am using a switch that supports 10,100,1000 Mbit/s full/half duplex connection. I have configured the hosts with a static ip 172.16.0.1-2-3/25. This is the output of ifconfig eth0 Link encap: Ethernet HWaddr ***** inet addr:172.16.0.3 Bcast:172.16.0.127 Mask:255.255.255.128 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:16 The output on H1 and H2 is perfectly matchable They are mutually reachable since i have tested the network with ping. I have forced the ethernet interface to work at 10M with ethtool -s eth0 speed 10 duplex full autoneg on this is the output of ethtool eth0 supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full S upported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10baseT/Full Advertised pause frame use: Symmetric A dvertised auto-negotiation: Yes Speed: 10Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: on MDI-X: Unknown Supports Wake-on: g Wake-on: d Current message level: 0x000000ff (255) drv probe link timer ifdown ifup rx_err tx_err Link detected: yes – I am doing an experimental test using nttcp to calculate the GOODPUT in the case that H1 and H2 at the same time send data to H3. Since the three links have the same forced capability and the amount of arrving data speed is 10 from H1+10 from H2--20M to H3 it would be expected a bottleneck effect and, due to the non reliable nature of udp, a packet loss. But this doesn't appen since the output of nttcp application shows the same number of byte sended and received. this is the output of nttcp on h3 nttcp -T -r -u 172.16.0.2 & nttcp -T -r -u 172.16.0.1 [1] 4071 Bytes Real s CPU s Real-MBit/s CPU-MBit/s Calls Real-C/s CPU-C/s l 8388608 13.74 0.05 4.8848 1398.0140 2049 149.14 42684.8 Bytes Real s CPU s Real-MBit/s CPU-MBit/s Calls Real-C/s CPU-C/s l 8388608 14.02 0.05 4.7872 1398.0140 2049 146.17 42684.8 1 8388608 13.56 0.06 4.9500 1118.4065 2051 151.28 34181.1 1 8388608 13.89 0.06 4.8310 1198.3084 2051 147.65 36623.0 – How is this possible? Am i missing something? Any help will be gratefully apprecciated, Best regards

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  • debian gateway using iptables

    - by meijuh
    I am having problems setting up a debian gateway server. My goal: Having eth1 the WAN interface. Having eth0 the LAN interface. Allow both ports 22 (SSH) and 80 (HTTP) accessed from the outside world on the gateway (SSH and HTTP run on this server). What I did was the following: Create a file /etc/iptables.rules with contents: /etc/iptables.rules: *nat -A POSTROUTING -o eth1 -j MASQUERADE COMMIT *filter -A INPUT -i lo -j ACCEPT -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -A INPUT -i eth1 -p tcp -m tcp --dport 22 -j ACCEPT -A INPUT -i eth1 -p tcp -m tcp --dport 80 -j ACCEPT -A INPUT -i eth1 -j DROP COMMIT edit /etc/network/interfaces as follows: /etc/network/interfaces: # The loopback network interface auto lo iface lo inet loopback pre-up iptables-restore < /etc/iptables.rules auto eth0 allow-hotplug eth0 iface eth0 inet dhcp #auto eth1 #allow-hotplug eth1 #iface eth1 inet dhcp allow-hotplug eth1 iface eth1 inet static address 217.119.224.51 netmask 255.255.255.248 gateway 217.119.224.49 dns-nameservers 217.119.226.67 217.119.226.68 Uncomment the rule net.ipv4.ip_forward=1 in /etc/sysctl.conf to allow packet forwarding. The static settings for eth1 such as the ip address I got from my router (which I want to replace); I simply copied these. I have a (windows) DNS + DHCP server on ip address 10.180.1.10, which assigns ip address 10.180.1.44 to eth0. What this server does is not really interesting it only maps domain names on our local network and assigns one static ip to the gateway. What works: on the gateway itself I can ping 8.8.8.8 and google.nl. So that is okey. What does not work: (1) Every machine connected to eth0 (indirectly via a switch) can not ping an ip or a domain. So I guess the gateway can not be found. (2) Also when I configure my linux machine (a laptop) to use a static ip 10.180.1.41, a mask and a gateway (10.180.1.44) I can not ping an ip or domain either. This means that maybe my iptables is incorrect of not loaded correctly. Or I maybe have to configure my DNS/DHCP on my windows machine. I have not reset the windows machine net, restart the DNS/DHCP services, should I do this? I did not install dnsmasq as desribed here: http://blog.noviantech.com/2010/12/22/debian-router-gateway-in-15-minutes/. I don't think this is necessary?

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  • SMB returns the entire file instead of header info

    - by billdlawson
    Starting a section of code checks for access to many data files (flat files so each table is a file) and when I do a packet capture, in our capture only the header info is sent by the server to the client. However I have one Customer who is using a SAN that gets the whole file instead of just the header info,and besides just being slower, this is causing file access issues. They have already turned off OPLOCKS at the server and at the workstations. This is not client server. The data files and the application reside on the server but the users run the application locally via a shortcut with a mapped drive or UNC. So when I simply select an option that prompts for a vehicle number, not tryng to select a record but rather simply verify the datafiles are accessible, that window opens in 1-2 seconds for me. When they do the same thing it takes 6-15 seconds after there several users are running the program. Maximum number of users is 15. The program has a lot of small modules, 800 .cob modules. So it is very chatty but these are datafiles. We have Wireshark captures that show he's pulling the whole file and we're just getting the header. Thier capture vs ours. We suspect the SAN. Has anyone ever heard of a SAN improperly interpreting runtime requests? So an SMB request. This is Acucobol-GT (now Microfocus). The application is written in COBOL. This is not a new program just a new problem. This is one customer of over a thousand who are otherwise running smoothly and we are totally stumped. All XP users, the server is Windows 2003 (with Virtual server) and I don't yet know the SAN info. Also we have many installations running virtual servers but only few on SANs or we just don't know it. This is not a network throught put issue, the load is less than 5% on the server and theer are no timeout or retransmits. PS If it wasn't for Wireshark I'd still be chasing my tail. An application trace file on thier installation just looks like they run slower. If you want the Wireshark trace file I can make it available. Thanks in advance - Please excuse my verbosity (word?) but I'm not sure what's relavent.

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