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• sniffing on a switched LAN

  - by shodanex

  Hi, I often find myself in the position of having to sniff on a connection between for example an arm board I am developing on, and another computer on the network, or out of the network. The easy situation is when I can install a sniffer on the computer talking to the embedded device. When it is not possible, I currently install an old 10Mb/s HUB. However I am afraid my HUB might stop working, and I would like to know some alternative. Here are the alternatives I could think of : Buy another HUB. Is that still possible ? Have some sort of ethernet sniffing bridge, like what they do for USB. I am afraid this kind of device is expensive. use ARP poisoning.

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• Bridging VirtualBox over OpenVPN TAP adapter on Windows

  - by Sean Edwards

  I'm trying to configure a virtual machine (VirtualBox guest running Backtrack 4) with a bridged adapter over a VPN connection. The VPN is is hosted by the cybersecurity club at my university, and connects to a sandboxed LAN designed for penetration testing against various servers that the club has built. My host (Windows 7 Ultimate) connects to the VPN fine and is assigned an IP through DHCP, but for some reason the VM can't do the same thing, and I'm not sure why. It's like OpenVPN is filtering out packets from the MAC address it doesn't recognize. I want the virtual machine to bridge over the VPN connection, because our IT office has very strict policies about what you can and can't do on the network. I want to be able to run active attacks (ARP spoofing, nmap, Nessus scans) in the sandbox environment without risking the traffic accidentally going over the university network and getting my internet access revoked. Bridging over the VPN connection and running all attacks from inside the VM would solve that problem. Any idea why the host can use this interface, but the VM can't?

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• SSH not working over IPSec tunnel (Strongswan)

  - by PattPatel

  I configured a small network on a cloud virtual machine. This virtual machine has a static IP address assigned to eth0 interface that I'll call $EXTIP. mydomain.com points to $EXTIP. Inside, I have some linux containers, that get their ip through DHCP in the Subnet 10.0.0.0/24 (i called the virtual interface nat ). They run some services that can be reached through DNAT. Then I wanted to connect to these containers through an IPSec tunnel, so I configured StrongSwan. ipsec.conf: conn %default dpdaction=none rekey=no conn remote keyexchange=ikev2 ike=######## left=[$EXTIP] leftsubnet=10.0.1.0/24,10.0.0.0/24 leftauth=pubkey lefthostaccess=yes leftcert=########.pem leftfirewall=yes leftid="#########" right=%any rightsourceip=10.0.1.0/24 rightauth=######## rightid=%any rightsendcert=never eap_identity=%any auto=add type=tunnel Everything works fine, IPSec clients get IPs of the 10.0.1.0/24 subnet and can reach the containers subnet. My problem is that I'm not able to get SSH connections over the tunnel. It simply does not work, ssh client does not produce any output. Sniffing with tcpdump gives: tcpdump: 09:50:29.648206 ARP, Request who-has 10.0.0.1 tell mydomain.com, length 28 09:50:29.648246 ARP, Reply 10.0.0.1 is-at 00:ff:aa:00:00:01 (oui Unknown), length 28 09:50:29.648253 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [S], seq 4007849772, win 29200, options [mss 1460,sackOK,TS val 1151153 ecr 0,nop,wscale 7], length 0 09:50:29.648296 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [S.], seq 2809522632, ack 4007849773, win 14480, options [mss 1460,sackOK,TS val 11482992 ecr 1151153,nop,wscale 6], length 0 09:50:29.677225 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [.], ack 2809522633, win 229, options [nop,nop,TS val 1151162 ecr 11482992], length 0 09:50:29.679370 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [P.], seq 0:23, ack 1, win 229, options [nop,nop,TS val 1151162 ecr 11482992], length 23 09:50:29.679403 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], ack 24, win 227, options [nop,nop,TS val 11483002 ecr 1151162], length 0 09:50:29.684337 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [P.], seq 1:32, ack 24, win 227, options [nop,nop,TS val 11483003 ecr 1151162], length 31 09:50:29.685471 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], seq 32:1480, ack 24, win 227, options [nop,nop,TS val 11483003 ecr 1151162], length 1448 09:50:29.685519 IP mydomain.com > 10.0.0.1: ICMP mydomain.com unreachable - need to frag (mtu 1422), length 556 09:50:29.685567 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], seq 32:1402, ack 24, win 227, options [nop,nop,TS val 11483003 ecr 1151162], length 1370 09:50:29.685572 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], seq 1402:1480, ack 24, win 227, options [nop,nop,TS val 11483003 ecr 1151162], length 78 09:50:29.714601 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [.], ack 32, win 229, options [nop,nop,TS val 1151173 ecr 11483003], length 0 09:50:29.714642 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [P.], seq 1480:1600, ack 24, win 227, options [nop,nop,TS val 11483012 ecr 1151173], length 120 09:50:29.723649 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [P.], seq 1393:1959, ack 32, win 229, options [nop,nop,TS val 1151174 ecr 11483003], length 566 09:50:29.723677 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], ack 24, win 227, options [nop,nop,TS val 11483015 ecr 1151173,nop,nop,sack 1 {1394:1960}], length 0 09:50:29.725688 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [.], ack 1480, win 251, options [nop,nop,TS val 1151177 ecr 11483003], length 0 09:50:29.952394 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [P.], seq 1480:1600, ack 24, win 227, options [nop,nop,TS val 11483084 ecr 1151173,nop,nop,sack 1 {1394:1960}], length 120 09:50:29.981056 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [.], ack 1600, win 251, options [nop,nop,TS val 1151253 ecr 11483084,nop,nop,sack 1 {1480:1600}], length 0 If you need it this is my iptables configuration file: iptables: *filter :INPUT ACCEPT [144:9669] :FORWARD DROP [0:0] :OUTPUT ACCEPT [97:15649] :interfacce-trusted - [0:0] :porte-trusted - [0:0] -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT -A FORWARD -j interfacce-trusted -A FORWARD -j porte-trusted -A FORWARD -j REJECT --reject-with icmp-host-unreachable -A FORWARD -d 10.0.0.1/32 -p tcp -m tcp --dport 80 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT -A FORWARD -d 10.0.0.1/32 -p tcp -m tcp --dport 443 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT -A FORWARD -d 10.0.0.3/32 -p tcp -m tcp --dport 1234 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT -A interfacce-trusted -i nat -j ACCEPT -A porte-trusted -d 10.0.0.1/32 -p tcp -m tcp --dport 80 -j ACCEPT -A porte-trusted -d 10.0.0.1/32 -p tcp -m tcp --dport 443 -j ACCEPT -A porte-trusted -d 10.0.0.3/32 -p tcp -m tcp --dport 1234 -j ACCEPT COMMIT *nat :PREROUTING ACCEPT [10:600] :INPUT ACCEPT [10:600] :OUTPUT ACCEPT [4:268] :POSTROUTING ACCEPT [18:1108] -A PREROUTING -d [$EXTIP] -p tcp -m tcp --dport 80 -j DNAT --to-destination 10.0.0.1:80 -A PREROUTING -d [$EXTIP] -p tcp -m tcp --dport 443 -j DNAT --to-destination 10.0.0.1:443 -A PREROUTING -d [$EXTIP] -p tcp -m tcp --dport 8069 -j DNAT --to-destination 10.0.0.3:1234 -A POSTROUTING -s 10.0.0.0/24 -o eth0 -m policy --dir out --pol ipsec -j ACCEPT -A POSTROUTING -s 10.0.1.0/24 -o nat -j MASQUERADE -A POSTROUTING -s 10.0.0.0/24 -o eth0 -j MASQUERADE COMMIT Probably I'm missing something stupid... Thanks in advance for helping :))

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• Unexpected network traffic?

  - by robwalker

  My internet connection is via a fixed wireless connection using a 900MHz Motorola Canopy module. The router reports a fairly consistent 32-64Kbps of incoming traffic on the WAN port. When I attached a PC directly to the port and run Wireshark, I get a dump showing a lot of chatter from other machines that I presume are connected to the same tower. This didn't include end-to-end traffic, but was there were a lot of ARP requests, SSDP traffic, ICMP and other network discovery type stuff. Is this 'normal' or does it suggest a misconfiguration somewhere? As far as I can tell there is no need for my modem to be receiving any of this traffic (other than wanting to know what the names of my neighbours machines and printers are!) Since the internet connection is slow at the best of time, having this amount of background noise seems very wasteful.

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• Multiple VLANs in the same subnet

  - by A.J.

  Is it possible to have multiple VLANs in the same subnet, with the same gateway address (TMG)? I want to avoid having many Subnets (and vNIC's in TMG) just to isolate sets of a few hosts. IP: 10.0.0.1 (TMG server) VLAN:1 ~ 3 IP: 10.0.0.11 ~ 20 (Hosts group 1) VLAN:1 IP: 10.0.0.21 ~ 30 (Hosts group 2) VLAN:2 IP: 10.0.0.31 ~ 40 (Hosts group 3) VLAN:3 Note that I don't want them to connect to each other, so ARP/inter-vlan routing (within the subnet) is not required. The gateway is running in a VM within ESXi 5, I can pass the VLans to the VM using VGT or VLan Range, but I don't know how the OS/TMG should handle them.

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• Get/Assign IP addresses assigned by the DHCP sever with DLink switches in between

  - by Ranjith Kumar

  In our office the setup is like we have a UBUNTU server with DHCP Server connected to all the PCS via 24 port and 8 port DLink switches. How can I find all the PCS(with client name, ip and mac address)in the network?? When I do "vi /var/lib/dhcp3/dhcpd.leases", I get all the ip addresses for the switches. I have used "arp-scan --interface=eth0 --localnet" to get all the IPs and MAC Addresses in my local network. I couldn't find any option to diplay client name. Also I would like to assign particular IP for a particular PC. I have done the changes in the dhcp.conf file but it is not working as they are not directly connected to DHCP-server(DLink switches in between). How can I assign IPs for PCs in this kind of setup. Thanks in advance

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• Changing Internet connection on ISA Server 2000

  - by garyb32234234

  Hi We are getting a new internet connection installed and will need to unplug the old one and connect this to our ISA Server 2000. Will this be a simple swap out job? We will be given a new ip, which i know i will have to enter into the external network card TCP/IP page. I will also be given the default gateway to enter. The ISP engineer said we may have to reset the ARP? cache, if we dont know how we will have to reset the ISA server? Has anyone any experience? The current connection is with the same ISP but it was owned by the business park were we are located and they linked up an ethernet port to what i assume is their own router. Hope you can help, i know that ISA 2000 is somewhat less easy to use than the newer versions.

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• Can't find a wireless access point's IP address after changing router IP/LAN settings

  - by flagg19

  I have a modem/router, Netgear DG834, and a wireless access point (AP), Netgear WG602. The AP is directly connected to the router. My old working configuration was: Router IP address : 192.168.0.1 Access point IP address: 192.168.0.10 My new configuration is: Router IP address : 192.168.1.1 Access point IP address: ???.???.???.??? I changed my router's IP address/LAN settings to set up a VPN with another Netgear router that had the same LAN configuration. The wireless network is still up and perfectly working, but I can't find the AP's IP address. I've tried broadcast ping but the AP won't respond. I looked at the router "attached devices", but it's not there. I've played around with Nmap and arp request but the AP is totally invisible. I can fix it by resetting it to factory settings, but I'm very interested in learning more about this problem. I'm also interested in network security and this fact of having an invisible AP well, it's something I'd like to understand.

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• How to troubleshoot slow powerconnect 62xx management interface

  - by Hannes

  Our Dell Powerconnect 62xx switches have a very high packetloss on the management interface. I presume this is caused by a new appliance which uses multicast for communication but I am not sure. Our network setup is following: servers a - Dell PC6248 | servers b - Dell PC6248 |- juniper core router servers c - Dell PC6248 | What we see is that the multicast traffic arrives at all servers (but only the servers b use the multicast) and I fear that this multicast traffic floods the switch management interface. The switches' management interfaces are reachable via vlan101, all other traffic is sent over other vlans. When I tcpdump on one of the 2 servers with a vlan 101 ip address, I only get a few arp requests but almost nothing. When I try to ping between these 2 servers, it works like a charm. I would like to know what a good way is to troubleshoot this problem and maybe help me understand what is going wrong on that subnet.

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• Command to see all Windows commands

  - by open_sourse

  When I type help in windows command line, it lists a whole bunch of commands. However I find that there is a whole set of commands that do not appear in this list, for e.g. many networking commands such as ping, tracert, arp, netstat, net etc. I am sure that there is also a whole bunch of non-networking command which is also not listed. So my question is this. Why are these additional commands not shown in help? Is there a subset/group of commands only that help shows? Is there any command/method to list all the commands that can be executed in windows? (I am not talking about additional .exes that get added to path when some new software is installed..)

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• How to know my wireless card has injection enabled?

  - by shrimpy

  I am playing around with aircrack. And was trying to see whether my wireless card on my laptop can pass the injection test And I end up seeing the following... does it mean my wireless card is not able to run aircrack? root@myubuntu:/home/myubuntu# iwconfig lo no wireless extensions. eth0 no wireless extensions. eth1 IEEE 802.11bg ESSID:"" Nickname:"" Mode:Managed Frequency:2.437 GHz Access Point: Not-Associated Bit Rate:54 Mb/s Tx-Power:24 dBm Retry min limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=5/5 Signal level=0 dBm Noise level=-57 dBm Rx invalid nwid:0 Rx invalid crypt:781 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 root@myubuntu:/home/myubuntu# aireplay-ng -9 eth1 ioctl(SIOCSIWMODE) failed: Invalid argument ARP linktype is set to 1 (Ethernet) - expected ARPHRD_IEEE80211, ARPHRD_IEEE80211_FULL or ARPHRD_IEEE80211_PRISM instead. Make sure RFMON is enabled: run 'airmon-ng start eth1 <#>' Sysfs injection support was not found either. root@myubuntu:/home/myubuntu#

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• aireplay - reading but not sending

  - by oneat

  I'm trying aircrack injection, everything is working I authenticated, but aireplay is not working aireplay-ng -3 -b 00:12:2A:01:74:05 -h 78:e4:00:87:71:8b mon0 18:53:03 Waiting for beacon frame (BSSID: 00:12:2A:01:74:05) on channel 7 Saving ARP requests in replay_arp-0817-185303.cap You should also start airodump-ng to capture replies. Read 4988 packets (0 ARPs, 4 ACKs), sent 0 packets...(0 pps) Why isn't it working? Why isn't it sending packets? 03:00.0 Network controller: Atheros Communications Inc. AR928X Wireless Network Adapter (PCI-Express) (rev 01) I tested injection on injection test in aircrack tutorial, despite driver wasn't patched.

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• Teaming/Spanning Switch Ports

  - by KTech

  I like to team NICs on my servers. Since most workstations are giga-bit anymore I want to provide my servers a bit more bandwidth. I've read various things that say I am/am not supposed to bond the ports on the switch. I see benefit in doing it as I'm not sure how the switch ARP table handles the same MAC address on multiple ports. Suggestions on the "ideal" way to do it? If it matters, I have mix (various locations) of Dell and HP, web managed, Layer 2 switches. Servers are mostly Dell with Broadcom NICs.

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• How can I tell if a host is bridged and acting as a router

  - by makerofthings7

  I would like to scan my DMZ for hosts that are bridged between subnets and have routing enabled. Since I have everything from VMWare servers, to load balancers on the DMZ I'm unsure if every host is configured correctly. What IP, ICMP, or SNMP (etc) tricks can I use to poll the hosts and determine if the host is acting as a router? I'm assuming this test would presume I know the target IP, but in a large network with many subnets, I'd have to test many different combinations of networks and see if I get success. Here is one example (ping): For each IP in the DMZ, arp for the host MAC Send a ICMP reply message to that host directed at an online host on each subnet I think that there is a more optimal way to get the information, namely from within ICMP/IP itself, but I'm not sure what low level bits to look for. I would also be interested if it's possible to determine the "router" status without knowing the subnets that the host may be connected to. This would be useful to know when improving our security posture.

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• Multiple network interfaces and UDP packets distribution

  - by Robert Kubrick

  I have a Linux server with 2 1Gb network interfaces eth1 and eth2. If I start 2 clients listening to the same multicast address and each client connects through a different NIC (say client 1 listens to the multicast through eth1 and client 2 through eth2), then client 2 gets duplicate UDP packets. If both clients use the same interface eth1 on the other hand, both clients work fine. I have already tried to set arp_filter and proxy_arp to 1 (arp flux issue) but it hasn't solved the issue. Is this a Linux kernel problem? Or is there another way to setup the interfaces correctly?

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• Network flooded with seemingly empty packets

  - by Adam Particka

  Let me preface this with the fact that I'm just a web developer at my company with little networking knowledge. Earlier today there was a department that lost all of their network connections so I popped open Wireshark and observed the influx of packets to my machine. There was normal traffic (ARP requests, etc.) coming in at ~50 packets every second. Then all of a sudden the log was flooded with packets arriving ~5000 a second. It looks as though they all contain the same data, just a looped sequence. We have someone here looking at it but I thought I would ask if anyone had seen anything like this before. Here's a selection from one of the captures in Wireshark. http://www.cloudshark.org/captures/06f950725c74

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• How does communication between 2 computers in a single network happen?

  - by learner

  Lets say I and my friend connect our computers with a LAN cable. I ping my friend with his IP address. How does it work? Since we are in the same network, we don't even need IP addresses, do we? Isn't IP addressing only relevant in case of inter-network communication? What will the ping command do with his IP address? How will it eventually find his physical address (NIC address)? (no ARP here, because that would involve a router at the edge of the network, which doesn't apply here). Am I wrong somewhere?

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• How can I transfer files to a Kindle Fire with a Micro-USB cable?

  - by Jeff

  I'm running Ubuntu 11.10, and when I connect my Kindle Fire to my computer via micro usb, it is not recognized automatically. Other usb devices, such as my ipod and digital camera, are recognized just fine. It does not appear to be a usb power issue, since the Kindle Fire wakes up from sleeping when it is plugged in. I never get the message on the Kindle telling me it is ready to accept files from the computer, though. Here are the last 15 lines of dmesg after plugging the kindle in: jeff@prime:~$ dmesg | tail -n 15 [45918.269671] ieee80211 phy0: wl_ops_bss_info_changed: arp filtering: enabled true, count 1 (implement) [45929.072149] wlan0: no IPv6 routers present [46743.224217] usb 1-1: new high speed USB device number 5 using ehci_hcd [46743.364623] scsi8 : usb-storage 1-1:1.0 [46744.366102] scsi 8:0:0:0: Direct-Access Amazon Kindle 0001 PQ: 0 ANSI: 2 [46744.366356] scsi: killing requests for dead queue [46744.372494] scsi: killing requests for dead queue [46744.384510] scsi: killing requests for dead queue [46744.392348] scsi: killing requests for dead queue [46744.392731] scsi: killing requests for dead queue [46744.396853] scsi: killing requests for dead queue [46744.397214] scsi: killing requests for dead queue [46744.400795] scsi: killing requests for dead queue [46744.401589] sd 8:0:0:0: Attached scsi generic sg2 type 0 [46744.407520] sd 8:0:0:0: [sdb] Attached SCSI removable disk And here are my mounted filesystems: jeff@prime:~$ df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 298594984 174663712 108763480 62% / udev 1407684 4 1407680 1% /dev tmpfs 566924 896 566028 1% /run none 5120 0 5120 0% /run/lock none 1417308 300 1417008 1% /run/shm /home/jeff/.Private 298594984 174663712 108763480 62% /home/jeff I should note that, since I got Dropbox working on my Kindle, the usb is no longer strictly necessary, but as a matter of principle I'd love to get it working.

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• Java CORBA Client Disconnects Immediately

  - by Benny

  I have built a Java CORBA application that subscribes to an event server. The application narrows and logs on just fine, but as soon as an event is sent to the client, it breaks with the error below. Please advise. 2010/04/25!13.00.00!E00555!enserver!EventServiceIF_i.cpp!655!PID(7390)!enserver - e._info=system exception, ID 'IDL:omg.org/CORBA/TRANSIENT:1.0' TAO exception, minor code = 54410093 (invocation connect failed; ECONNRESET), completed = NO EDIT: Please note, this only happens when running on some machines. It works on some, but not others. Even on the same platform (I've tried Windows XP/7 and CentOS linux) Some work, some don't... Here is the WireShark output...looks like the working PC is much more interactive with the network compared to the non-working PC. Working PC No. Time Source Destination Protocol Info 62 28.837255 10.10.10.209 10.10.10.250 TCP 50169 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 63 28.907068 fe80::5de0:8d21:937e:c649 ff02::1:3 LLMNR Standard query A isatap 64 28.907166 10.10.10.209 224.0.0.252 LLMNR Standard query A isatap 65 29.107259 10.10.10.209 10.255.255.255 NBNS Name query NB ISATAP<00> 66 29.227000 10.10.10.250 10.10.10.209 TCP 23120 > 50169 [SYN, ACK] Seq=0 Ack=1 Win=32768 Len=0 MSS=1260 WS=0 67 29.227032 10.10.10.209 10.10.10.250 TCP 50169 > 23120 [ACK] Seq=1 Ack=1 Win=66560 Len=0 68 29.238063 10.10.10.209 10.10.10.250 GIOP GIOP 1.1 Request s=326 id=5 (two-way): op=logon 69 29.291765 10.10.10.250 10.10.10.209 GIOP GIOP 1.1 Reply s=420 id=5: No Exception 70 29.301395 10.10.10.209 10.10.10.250 GIOP GIOP 1.1 Request s=369 id=6 (two-way): op=registerEventStat 71 29.348275 10.10.10.250 10.10.10.209 GIOP GIOP 1.1 Reply s=60 id=6: No Exception 72 29.405250 10.10.10.209 10.10.10.250 TCP 50170 > telnet [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 73 29.446055 10.10.10.250 10.10.10.209 TCP telnet > 50170 [SYN, ACK] Seq=0 Ack=1 Win=32768 Len=0 MSS=1260 WS=0 74 29.446128 10.10.10.209 10.10.10.250 TCP 50170 > telnet [ACK] Seq=1 Ack=1 Win=66560 Len=0 75 29.452021 10.10.10.209 10.10.10.250 TELNET Telnet Data ... 76 29.483537 10.10.10.250 10.10.10.209 TELNET Telnet Data ... 77 29.483651 10.10.10.209 10.10.10.250 TELNET Telnet Data ... 78 29.523463 10.10.10.250 10.10.10.209 TCP telnet > 50170 [ACK] Seq=4 Ack=5 Win=32768 Len=0 79 29.554954 10.10.10.209 10.10.10.250 TCP 50169 > 23120 [ACK] Seq=720 Ack=505 Win=66048 Len=0 Non-working PC No. Time Source Destination Protocol Info 1 0.000000 10.10.10.209 10.10.10.250 TCP 64161 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 2 2.999847 10.10.10.209 10.10.10.250 TCP 64161 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 3 4.540773 Cisco_3c:78:00 Cisco-Li_55:87:72 ARP Who has 10.0.0.1? Tell 10.10.10.209 4 4.540843 Cisco-Li_55:87:72 Cisco_3c:78:00 ARP 10.0.0.1 is at 00:1a:70:55:87:72 5 8.992284 10.10.10.209 10.10.10.250 TCP 64161 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260

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• Strange traffic on fresh Ubuntu Server install

  - by Fishy

  I've just installed Ubuntu Server on my home box after becoming partially familiar with it at work and wanting to train up as a Pen Tester. I installed the latest version on a logical partition (the main one contained Win7), and selected none of the extra modules (I think). I installed ngrep and fired it up (along with TCPdump) and immediately saw some strange traffic which I am unable to identify. My pc is sending out UDP packets every couple of seconds to a seemingly random series of IP addresses, all on the same port (47669 - though I did also see it use another port for a while). I watched it do this for about 20 mins, whilst trying to work out why it was doing it. The only other traffic was the odd ARP request for the router and SSDP UPnP broadcasts from the router. Anyone know what this is, or have any advice on how best to find out? Thanks. EDIT: Actually, it's not my box generating the traffic. It's receiving the traffic on that port, from a series of IP addresses, and returning 'port unreachable' messages.

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• Can't connect nonlocally after 12.10 upgrade

  - by user101815

  I've just upgraded one of my systems from 12.04 to 12.10. Now I can't connect on that system beyond my local network. Connections within the local network seem to work fine, and I can make nonlocal connections from other machines (like the one I'm asking this question from). I suspect that some routing information has been messed up, but I don't know where to look for it. It's not a nameserver problem -- pinging outside sites by their IP addresses doesn't work either. I have another laptop next to this one, also running Kubuntu 12.10. On the one that can't connect, arp produces no output. On the other one, it produces 192.168.0.1 ether 00:23:69:fa:ce:ae C wlan0 On the working machine, the output of netstat starts with some tcp entries. On the nonworking one, those entries are absent. I asked this question on the Ubuntu forum but haven't gotten any answers there. One further complication: since the troublesome machine has no outside connection, it's extremely difficult to download anything to it. For what it's worth, "ping 8.8.8.8" produces "connect: Network is unreachable". Update: after a lot of fiddling, I have my external world back. I don't know what the key action was, but the first indication of progress was that "ping 8.8.8.8" worked. At that point I still didn't have a working nameserver, so external URLs didn't work. But I did this (based on an online post, of course): sudo dpkg-reconfigure resolvconf and answered Yes to all prompts. That did the trick!! Apparently my problem was unique, or close to it, since I couldn't find any online references to it: local net working, remote net not working, including explicit IP addresses. So I suppose that if no one else has this problem, no one cares about the solution!!

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• Extended service set help [closed]

  - by Cygnus X

  Sorry, this is going to be long and rambly. So, at home my network is set up as such: I have a "master router" that handles DHCP, from there I have a basic 5 port switch, and coming off that, I have a second router that I put in access point mode so that I could have better wireless coverage in my house. I cant seem to access it through a web browser since the master router kicked in and assigned it an ip address. But, i told you all that story, so that i could tell you this story. At the company I work for, they are trying to set up wireless cameras, according to the manual for these, in order to connect these cameras to our network, we need to get into the wireless router and associate the router with the cameras, but the problem is, the network is setup like my home network. Theres a "master router" which is a windows 2003 server, and then a wireless router in AP mode dishing out wireless access. I cant get into the router (by the way I'm not the system admin for the company, nor do i know jack squat about windows server , nor can I easily get in contact with the system admin. (quite the cluster f*k, eh?)) I've tried using wireshark to find the routers ip, dug through arp tables, tried plugging straight into the router, but I cant seem to get into the damn thing. Any ideas/suggestions would be greatly appreciated.

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• How to stop a ICMP attack?

  - by cumhur onat

  We are under a heavy icmp flood attack. Tcpdump shows the result below. Altough we have blocked ICMP with iptables tcpdump still prints icmp packets. I've also attached iptables configuration and "top" result. Is there any thing I can do to completely stop icmp packets? [root@server downloads]# tcpdump icmp -v -n -nn tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes 03:02:47.810957 IP (tos 0x0, ttl 49, id 16007, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 124, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.811559 IP (tos 0x0, ttl 49, id 16010, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 52, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.811922 IP (tos 0x0, ttl 49, id 16012, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 122, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.812485 IP (tos 0x0, ttl 49, id 16015, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 126, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.812613 IP (tos 0x0, ttl 49, id 16016, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 122, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.812992 IP (tos 0x0, ttl 49, id 16018, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 122, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.813582 IP (tos 0x0, ttl 49, id 16020, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 52, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.814092 IP (tos 0x0, ttl 49, id 16023, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 120, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.814233 IP (tos 0x0, ttl 49, id 16024, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 120, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.815579 IP (tos 0x0, ttl 49, id 16025, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 50, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.815726 IP (tos 0x0, ttl 49, id 16026, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 IP (tos 0x0, ttl 50, id 31864, offset 0, flags [none], proto: ICMP (1), length: 76) 77.92.136.196 > 94.201.175.188: [|icmp] 03:02:47.815890 IP (tos 0x0, ttl 49, id 16027, offset 0, flags [none], proto: ICMP (1), length: 56) 80.227.64.183 > 77.92.136.196: ICMP redirect 94.201.175.188 to host 80.227.64.129, length 36 iptables configuration: [root@server etc]# iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination ofis tcp -- anywhere anywhere tcp dpt:mysql ofis tcp -- anywhere anywhere tcp dpt:ftp DROP icmp -- anywhere anywhere Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination DROP icmp -- anywhere anywhere Chain ofis (2 references) target prot opt source destination ACCEPT all -- OUR_OFFICE_IP anywhere DROP all -- anywhere anywhere top: top - 03:12:19 up 400 days, 15:43, 3 users, load average: 1.49, 1.67, 2.61 Tasks: 751 total, 3 running, 748 sleeping, 0 stopped, 0 zombie Cpu(s): 8.2%us, 1.0%sy, 0.0%ni, 87.9%id, 2.1%wa, 0.1%hi, 0.7%si, 0.0%st Mem: 32949948k total, 26906844k used, 6043104k free, 4707676k buffers Swap: 10223608k total, 0k used, 10223608k free, 14255584k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 36 root 39 19 0 0 0 R 100.8 0.0 17:03.56 ksoftirqd/11 10552 root 15 0 11408 1460 676 R 5.7 0.0 0:00.04 top 7475 lighttpd 15 0 304m 22m 15m S 3.8 0.1 0:05.37 php-cgi 1294 root 10 -5 0 0 0 S 1.9 0.0 380:54.73 kjournald 3574 root 15 0 631m 11m 5464 S 1.9 0.0 0:00.65 node 7766 lighttpd 16 0 302m 19m 14m S 1.9 0.1 0:05.70 php-cgi 10237 postfix 15 0 52572 2216 1692 S 1.9 0.0 0:00.02 scache 1 root 15 0 10372 680 572 S 0.0 0.0 0:07.99 init 2 root RT -5 0 0 0 S 0.0 0.0 0:16.72 migration/0 3 root 34 19 0 0 0 S 0.0 0.0 0:00.06 ksoftirqd/0 4 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/0 5 root RT -5 0 0 0 S 0.0 0.0 1:10.46 migration/1 6 root 34 19 0 0 0 S 0.0 0.0 0:01.11 ksoftirqd/1 7 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/1 8 root RT -5 0 0 0 S 0.0 0.0 2:36.15 migration/2 9 root 34 19 0 0 0 S 0.0 0.0 0:00.19 ksoftirqd/2 10 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/2 11 root RT -5 0 0 0 S 0.0 0.0 3:48.91 migration/3 12 root 34 19 0 0 0 S 0.0 0.0 0:00.20 ksoftirqd/3 13 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/3 uname -a [root@server etc]# uname -a Linux thisis.oursite.com 2.6.18-238.19.1.el5 #1 SMP Fri Jul 15 07:31:24 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux arp -an [root@server downloads]# arp -an ? (77.92.136.194) at 00:25:90:04:F0:90 [ether] on eth0 ? (192.168.0.2) at 00:25:90:04:F0:91 [ether] on eth1 ? (77.92.136.193) at 00:23:9C:0B:CD:01 [ether] on eth0

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• Stop duplicate icmp echo replies when bridging to a dummy interface?

  - by mbrownnyc

  I recently configured a bridge br0 with members as eth0 (real if) and dummy0 (dummy.ko if). When I ping this machine, I receive duplicate replies as: # ping SERVERA PING SERVERA.domain.local (192.168.100.115) 56(84) bytes of data. 64 bytes from SERVERA.domain.local (192.168.100.115): icmp_seq=1 ttl=62 time=113 ms 64 bytes from SERVERA.domain.local (192.168.100.115): icmp_seq=1 ttl=62 time=114 ms (DUP!) 64 bytes from SERVERA.domain.local (192.168.100.115): icmp_seq=2 ttl=62 time=113 ms 64 bytes from SERVERA.domain.local (192.168.100.115): icmp_seq=2 ttl=62 time=113 ms (DUP!) Using tcpdump on SERVERA, I was able to see icmp echo replies being sent from eth0 and br0 itself as follows (oddly two echo request packets arrive "from" my Windows box myhost): 23:19:05.324192 IP myhost.domain.local > SERVERA.domain.local: ICMP echo request, id 512, seq 43781, length 40 23:19:05.324212 IP SERVERA.domain.local > myhost.domain.local: ICMP echo reply, id 512, seq 43781, length 40 23:19:05.324217 IP myhost.domain.local > SERVERA.domain.local: ICMP echo request, id 512, seq 43781, length 40 23:19:05.324221 IP SERVERA.domain.local > myhost.domain.local: ICMP echo reply, id 512, seq 43781, length 40 23:19:05.324264 IP SERVERA.domain.local > myhost.domain.local: ICMP echo reply, id 512, seq 43781, length 40 23:19:05.324272 IP SERVERA.domain.local > myhost.domain.local: ICMP echo reply, id 512, seq 43781, length 40 It's worth noting, testing reveals that hosts on the same physical switch do not see DUP icmp echo responses (a host on the same VLAN on another switch does see a dup icmp echo response). I've read that this could be due to the ARP table of a switch, but I can't find any info directly related to bridges, just bonds. I have a feeling my problem lay in the stack on linux, not the switch, but am opened to any suggestions. The system is running centos6/el6 kernel 2.6.32-71.29.1.el6.i686. How do I stop ICMP echo replies from being sent in duplicate when dealing with a bridge interface/bridged interfaces? Thanks, Matt [edit] Quick note: It was recommended in #linux to: [08:53] == mbrownnyc [gateway/web/freenode/] has joined ##linux [08:57] <lkeijser> mbrownnyc: what happens if you set arp_ignore to 1 for the dummy interface? [08:59] <lkeijser> also set arp_announce to 2 for that interface [09:24] <mbrownnyc> lkeijser: I set arp_annouce to 2, arp_ignore to 2 in /etc/sysctl.conf and rebooted the machine... verifying that the bits are set after boot... the problem is still present I did this and came up empty. Same dup problem. I will be moving away from including the dummy interface in the bridge as: [09:31] == mbrownnyc [gateway/web/freenode/] has joined #Netfilter [09:31] <mbrownnyc> Hello all... I'm wondering, is it correct that even with an interface in PROMISC that the kernel will drop /some/ packets before they reach applications? [09:31] <whaffle> What would you make think so? [09:32] <mbrownnyc> I ask because I am receiving ICMP echo replies after configuring a bridge with a dummy interface in order for ipt_netflow to see all packets, only as reported in it's documentation: http://ipt-netflow.git.sourceforge.net/git/gitweb.cgi?p=ipt-netflow/ipt-netflow;a=blob;f=README.promisc [09:32] <mbrownnyc> but I do not know if PROMISC will do the same job [09:33] <mbrownnyc> I was referred here from #linux. any assistance is appreciated [09:33] <whaffle> The following conditions need to be met: PROMISC is enabled (bridges and applications like tcpdump will do this automatically, otherwise they won't function). [09:34] <whaffle> If an interface is part of a bridge, then all packets that enter the bridge should already be visible in the raw table. [09:35] <mbrownnyc> thanks whaffle PROMISC must be set manually for ipt_netflow to function, but [09:36] <whaffle> promisc does not need to be set manually, because the bridge will do it for you. [09:36] <whaffle> When you do not have a bridge, you can easily create one, thereby rendering any kernel patches moot. [09:36] <mbrownnyc> whaffle: I speak without the bridge [09:36] <whaffle> It is perfectly valid to have a "half-bridge" with only a single interface in it. [09:36] <mbrownnyc> whaffle: I am unfamiliar with the raw table, does this mean that PROMISC allows the raw table to be populated with packets the same as if the interface was part of a bridge? [09:37] <whaffle> Promisc mode will cause packets with {a dst MAC address that does not equal the interface's MAC address} to be delivered from the NIC into the kernel nevertheless. [09:37] <mbrownnyc> whaffle: I suppose I mean to clearly ask: what benefit would creating a bridge have over setting an interface PROMISC? [09:38] <mbrownnyc> whaffle: from your last answer I feel that the answer to my question is "none," is this correct? [09:39] <whaffle> Furthermore, the linux kernel itself has a check for {packets with a non-local MAC address}, so that packets that will not enter a bridge will be discarded as well, even in the face of PROMISC. [09:46] <mbrownnyc> whaffle: so, this last bit of information is quite clearly why I would need and want a bridge in my situation [09:46] <mbrownnyc> okay, the ICMP echo reply duplicate issue is likely out of the realm of this channel, but I sincerely appreciate the info on the kernels inner-workings [09:52] <whaffle> mbrownnyc: either the kernel patch, or a bridge with an interface. Since the latter is quicker, yes [09:54] <mbrownnyc> thanks whaffle [edit2] After removing the bridge, and removing the dummy kernel module, I only had a single interface chilling out, lonely. I still received duplicate icmp echo replies... in fact I received a random amount: http://pastebin.com/2LNs0GM8 The same thing doesn't happen on a few other hosts on the same switch, so it has to do with the linux box itself. I'll likely end up rebuilding it next week. Then... you know... this same thing will occur again. [edit3] Guess what? I rebuilt the box, and I'm still receiving duplicate ICMP echo replies. Must be the network infrastructure, although the ARP tables do not contain multiple entries. [edit4] How ridiculous. The machine was a network probe, so I was (ingress and egress) mirroring an uplink port to a node that was the NIC. So, the flow (must have) gone like this: ICMP echo request comes in through the mirrored uplink port. (the real) ICMP echo request is received by the NIC (the mirrored) ICMP echo request is received by the NIC ICMP echo reply is sent for both. I'm ashamed of myself, but now I know. It was suggested on #networking to either isolate the mirrored traffic to an interface that does not have IP enabled, or tag the mirrored packets with dot1q.

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• Android: How to obtain Mac Address of WiFi Network Interface?

  - by Gubatron

  It seems the java.net.NetworkInterface implementation of android does not have a byte[] getHardwareAddress() method http://developer.android.com/reference/java/net/NetworkInterface.html I've found several forums of people trying to do this with no definitive answer, I need to get a somewhat cross-device UUID, so I can't rely on phone numbers or in ANDROID_ID (which can be overwritten and which I think depends on the user having a google account) http://developer.android.com/reference/android/provider/Settings.Secure.html#ANDROID_ID In linux you can use ifconfig or read from /proc/net/arp and you can easily get the Hardware address. Is there a file in android that I can read? There has to be a way to get this address since it's shown in the "Settings About Phone Status" of the phone.

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