telnet on local LAN question

[Paul Allen Newell]

[inline]

On 8/20/2011 3:42 AM, Craig White wrote:
>
> If it looks something like this on your SMTP server
> # netstat -an
> Active Internet connections (servers and established)
> Proto R-Q S-Q Local Address  Foreign Address  State
> tcp    0   0  0.0.0.0:25      0.0.0.0:*      LISTEN

Verified this to be the case on sending and receiving machine.

>
>
> then indeed it is listening on all interfaces (0.0.0.0 port 25) for
> connections from all addresses any originating port (0.0.0.0:*) which is
> what we're after.
>
> If you get connection refused, there is probably only a few
> possibilities...
>
> 1 - /etc/hosts.deny  - is there something in that file that would cause
> your system to reject connections?

Both hosts.deny and hosts.allow have no active lines (the default from 
installation)

> 2 - your network hardware...

I am presuming you are referring to my Linksys WRT54GL router which 
connects the two machines. I wouldn't know how to test to see if there 
was a problem, I can attest to my trying to remove it from the equation 
by disabling firewall and therefore not blocking/filtering anything. I 
am not touching VPN since that shouldn't be involved (?) and have no 
rules under access restrictions and no entries under applications/games 
(and wouldn't expect to need such given that ssh/22 works)

> 3 - your network configurations

Everything is statically assigned 192.168.2.x addresses, the Verizon 
modem is 192.168.1.1 but all my tests are local to the LAN between 
192.168.2.10 and 192.168.2.11 through Linksys 192.168.2.3 (triple 
checked for typos)

I would expect ssh to fail if I had any problems with my network 
configurations but it is happily doing the right thing.

> Baby steps... start on the computer that is the SMTP server.
> telnet 127.0.0.1 25 # does it connect?

Yes, it says "trying", "connected", and then "220 chowder.localdomain 
ESMTP Sendmail 8.14.4/8.14.4; <date>

Chowder is 192.168.2.11.

Get same results on chalupa (192.168.2.10)
> telnet 192.168.2.10 25 # or whatever address is listed for 'eth0' - does
> it connect?

This works. On both machines, I can do telnet 192.168.2.{10,11} ... 
telnet to self through port 25 and telnet to the other machine through 
port 25

> After you can connect to port 25 on both the lo and eth0 addresses, you
> can move to another machine and see if you can telnet to the same
> 192.168.2.x IP address used above. It should work or it's almost certain
> that the problem is caused by 1 of the 3 things I listed above.
>
> Craig
>
>
 From what I can tell, all tests using telnet via port 25 work, all test 
with mail do not work.

Onto Tim's email(s) ...

Thanks,
Paul