Re: OT: Telenet to terminal server dropping -ubuntu 10 driving

Weird. I've seen, a long time ago, some crappy server that would
hang when the connected port was over 32k. Reason was that it was
being treated as a signed short and would not like negative
port numbers.

That may be consistent with this happening after a while of working.
OS may start with low port numbers and start climbing.

On the other hand, I would try to single the culprit. Do you have
some ohter telnet server to try ?

-Carlos

Radioactive Frog @ 22/01/2011 22:08 -0300 dixit:
> Has anyone seen this telnet issue?
> I am connected to my 2511 terminal server using telnet from my laptop. It
> will work for something 2 or 3 hours (not timed) perfectly.
> then all of sudden ping from my laptop to Terminal server still works but
> all my telnet windows hung , see below .
>
>
> DSL/WIFI-RTR------wifi----LAPTOP
> |
> |-----10/100 LANwire--------Terminal Server---to lab gears
>
> both laptop and terminal servers are in the same subnet no firewall in
> between etc. other PC from my WLAN can telnet okay, its just the my laptop.
>
> Radioactive_at_frog ~/Desktop $ telnet 50.1.3.2
> Trying 50.1.3.2...
> Connected to 50.1.3.2.
> Escape character is '^]'.
>
>
> At the same time I have another router which I telnet from my laptop shows
> the same issue "escape character blah" and nothing happens after that. I
> dont get to put user/pass.
>
> So it's just not the terminal server.
>
> Tried a little bit digging on it and the fix was "enable" disable my
> wireless connection. i.e. on my IBM R61p press Fn key + F5.
> I can telnet after that and access lab normally.
>
> resetting TCP stack --> /etc/init.d/networking restart didn't fix it.
>
> No firewall configured on this. So I was wondering
>
>
>
> frog Desktop # tcpdump -ni wlan0 | grep 50.1.3
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on wlan0, link-type EN10MB (Ethernet), capture size 65535 bytes
>
> 12:00:54.313282 IP 50.1.3.15.53851 > 50.1.3.2.23: Flags [P.], seq
> 2208563960:2208563987, ack 1599023550, win 5840, length 27
> 12:00:55.982996 IP 50.1.3.15.60803 > 50.1.3.2.23: Flags [S], seq 382968090,
> win 5840, options [mss 1460,sackOK,TS val 4156193 ecr 0,nop,wscale 6],
> length 0
> 12:00:56.004516 IP 50.1.3.2.23 > 50.1.3.15.60803: Flags [S.], seq
> 3537695090, ack 382968091, win 4128, options [mss 1460], length 0
> 12:00:56.004551 IP 50.1.3.15.60803 > 50.1.3.2.23: Flags [.], ack 1, win
> 5840, length 0
> 12:00:56.004675 IP 50.1.3.15.60803 > 50.1.3.2.23: Flags [P.], seq 1:28, ack
> 1, win 5840, length 27
> 12:00:56.213642 IP 50.1.3.2.23 > 50.1.3.15.60803: Flags [.], ack 28, win
> 4101, length 0
>
> .15 = my laptop IP
> .2 = Terminal srv IP
>
> see above tcpdump , laptop (.15) keep sending ack but never get syn.
>
> It's just my lapotp that is playing up. SSH works but not the telnet.
>
>
> Anyone have seen above?
> I have upgraded kernel to the latest but still seeing this happening. I can
> access everything else but not the telnet.
> i can access the internet etc okay on my laptop. ssh to other switch in the
> same subnet is okay. changed the cable.
>
>
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-- 
Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net