Supplemental information. I have now done this in two locations (home and at UAT) using 3 machines in each location (lapdog2 in both) and different routers in each. I can ssh from lapdog2 to any other with one exception (see next paragraph). I can also ssh from other machine to any other except lapdog2 and the same exception.
The exception is damselfish which is a netbook running ubuntu 11.04 like lapdog2 (a laptop). Ubuntu 11.04 does not seem to be the common thread as hammerhead works both ways and it is a desktop running 11.04. Its hard to imaging laptops being the common thread but ...
On Sat, Jun 18, 2011 at 1:02 PM, Joseph Sinclair <plug-discussion@stcaz.net> wrote:
Based on what you're seeing below, I'd suggest looking at the IP setup on the machines and any router/gateway between the two machines.
It looks like something is allowing the ICMP traffic but blocking or loosing the TCP connect for port 22.
It might help to run the following commands on each machine to look for inconsistencies or errors:
ifconfig -a
ip addr list
ip neigh
ip route
larry@lapdog2:~$ ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:16:36:e6:1b:b9
inet addr:192.168.2.124 Bcast:192.168.2.255 Mask:255.255.255.0
inet6 addr: fe80::216:36ff:fee6:1bb9/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:4187 errors:0 dropped:0 overruns:0 frame:0
TX packets:4369 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1349793 (1.3 MB) TX bytes:621589 (621.5 KB)
Interrupt:18 Memory:da000000-da020000
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:12 errors:0 dropped:0 overruns:0 frame:0
TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:720 (720.0 B) TX bytes:720 (720.0 B)
wlan0 Link encap:Ethernet HWaddr 00:19:d2:37:3c:33
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)
larry@lapdog2:~$ ip addr list
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:16:36:e6:1b:b9 brd ff:ff:ff:ff:ff:ff
inet 192.168.2.124/24 brd 192.168.2.255 scope global eth0
inet6 fe80::216:36ff:fee6:1bb9/64 scope link
valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
link/ether 00:19:d2:37:3c:33 brd ff:ff:ff:ff:ff:ff
larry@lapdog2:~$ ip neigh
192.168.2.1 dev eth0 lladdr 00:18:f8:3e:19:c1 REACHABLE
larry@lapdog2:~$ ip route
192.168.2.0/24 dev eth0 proto kernel scope link src 192.168.2.124 metric 1
169.254.0.0/16 dev eth0 scope link metric 1000
default via 192.168.2.1 dev eth0 proto static
larry@lapdog2:~$
Some *possible* causes:
1) More than one machine thinks it has IP 192.168.2.124 and there is an ARP conflict.Verified not true2) You have VLAN's setup on the router and the tagging is off or the router isn't passing TCP traffic between the VLAN's.
No VLANs
3) The two machines have subnet masks that make them think they're on different networks (e.g. 255.255.255.0 and 255.255.255.252 or /24 and /30)
All subnet masks are 255.255.255.0
If the machines are DHCP, have both release and renew their lease (and make sure there's only one DHCP server on the network!).
Verified only one dhcp server
If they're static configured, check /etc/network/interfaces and make sure the subnet mask is the same on both.
Only one machine (fogtest) is staticly configured )on both routers) as a static IP issued by DHCP
Dig through your router configuration (I assume you only have one router, if not temporarily remove all but one router) to make sure you don't have VLAN's setup or that they're properly configured
Only one router in each loaction and they seem correct
Check the ARP tables on the machines and the router ("ip neigh" at the command line on each machine, router depends on it's interface) to make sure you don't have duplicates and the MAC address matches for each IP address on the different machines
I'll have to research how to do that.
example (you may see many more entries than this) (Note that 10.23.124.104 is visible on both and the MAC value matches):
Machine 1
10.23.124.104 dev eth0 lladdr 02:49:5a:9e:e2:6c STALE
10.23.124.123 dev eth0 lladdr 03:1d:7f:7f:4d:2d STALE
Machine 2
10.23.124.104 dev eth0 lladdr 02:49:5a:9e:e2:6c STALE
10.23.124.125 dev eth0 lladdr 03:1e:4f:73:29:10 STALE
There should be only one entry for each IP address in the list on each machine; for a given IP address, all machines should see the same MAC address.
Hopefully that helps. Inconsistent network issues like this are always difficult to track down.
<<SNIPSNIPSNIP>>
> Again, name/ip resolution is not a problem and is always working correctly.<<SNIPSNIPSNIP>>
> BTW, here is an attempt from today:
> larry@fogtest:~$ ssh -v lapdog2
> OpenSSH_5.3p1 Debian-3ubuntu6, OpenSSL 0.9.8k 25 Mar 2009
> debug1: Reading configuration data /etc/ssh/ssh_config
> debug1: Applying options for *
> debug1: Connecting to lapdog2 [192.168.2.124] port 22.
> debug1: connect to address 192.168.2.124 port 22: Connection timed out
> ssh: connect to host lapdog2 port 22: Connection timed out
> larry@fogtest:~$ ping -c 3 lapdog2
> PING lapdog2 (192.168.2.124) 56(84) bytes of data.
> 64 bytes from lapdog2 (192.168.2.124): icmp_seq=1 ttl=64 time=0.587 ms
> 64 bytes from lapdog2 (192.168.2.124): icmp_seq=2 ttl=64 time=0.856 ms
> 64 bytes from lapdog2 (192.168.2.124): icmp_seq=3 ttl=64 time=0.996 ms
>
> --- lapdog2 ping statistics ---
> 3 packets transmitted, 3 received, 0% packet loss, time 2002ms
> rtt min/avg/max/mdev = 0.587/0.813/0.996/0.169 ms
> larry@fogtest:~$
>
> Clearly the issue seems to be what is blocking communication to port 22 even
> though sshd is listening on it, iptables seems to allow it and ufw was
> disabled yesterday and being enabled today seems to change nothing.
>
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