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Old 05-10-2014, 02:20 PM   #1
DBrenchley
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Registered: May 2014
Posts: 5

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Telnet: Connection closed by a foreign host


Good day:

I know just enough about Linux to get into trouble; appreciate your
patience ... ;-)

I've setup a SLES 11.3 server (Xen Hypervisor / SLES 11.3 DomU) as a
gateway ahead of 3 network switches. I'm masquerading the switch
management ip's.

There are (2) 10G switches whose management interfaces are attached to a
1G Switch. The 1G switch employs in-band management. I've setup the port
forwarding:

0/0 8123 0/0 192.168.50.201 23
0/0 8223 0/0 192.168.50.202 23
0/0 8323 0/0 192.168.50.202 23
0/0 8122 0/0 192.168.50.201 22
0/0 8222 0/0 192.168.50.202 22
0/0 8322 0/0 192.168.50.202 22

Remotely I can Telnet or SSH w/ no issues into the 10G switches but
attempts to get into the 1G results in no activity and the client window
closes OR I'll get a login challenge but the console appears
unresponsive and the client window eventually closes.

From the Guest VM I get the login challenge; I can enter credentials;
the connection opens; then immediately closes w/ the message "Connection
Closed by Foreign Host".

I can ping all the switches via the private network but the 1G shows
response times approaching .5 secs ....

From the vantage point of the private network I can Telnet/SSH perfectly
fine.

Being a total dunce .. I appreciate any suggestions as to how to debug
this ..

THANKS !!!
 
Old 05-15-2014, 02:52 AM   #2
Andy Alt
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Registered: Jun 2004
Location: Minnesota, USA
Distribution: Slackware64-stable, Manjaro, Debian64 stable
Posts: 528

Rep: Reputation: 167Reputation: 167
Have you used 'nmap' to verify open ports from within whichever network you're trying to connect from?
 
Old 05-15-2014, 03:11 PM   #3
DBrenchley
LQ Newbie
 
Registered: May 2014
Posts: 5

Original Poster
Rep: Reputation: Disabled
THANKS Andy .. yep .. all is good there .. actually determined the issue .. though not yet sure of the resolve.
The 10G switches have a fixed untagged management vLan @ 4095
The 1G uses in band and 4095 is a disallowed vLan (personally I think it's used for management but I have found docs stating that)
I set up a vLan on the one 1G for 4094 and as it's untagged it 'should' work .. and for all network traffic less it's own management it does.
I'm talking to the switch manufacturer .. so please consider this issue closed ..
 
Old 05-16-2014, 01:49 AM   #4
Andy Alt
Member
 
Registered: Jun 2004
Location: Minnesota, USA
Distribution: Slackware64-stable, Manjaro, Debian64 stable
Posts: 528

Rep: Reputation: 167Reputation: 167
Quote:
Originally Posted by DBrenchley View Post
I'm talking to the switch manufacturer .. so please consider this issue closed ..
Okay. You can mark this thread as solved using the "thread tools" link near the top.
 
  


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