2.1.90 - weird telnet hang

Mitch Adair (mitch@acan.net)
Sat, 21 Mar 1998 12:22:40 -0600 (CST)

Just had a very odd hang, or something, while telneting to a 2.0.33 server
from my 2.1.90 home machine. I don't think this is the same as the reports
of sluggish interactive tcp perf. with .90, but I dunno. I was reading
email on the 0.30 server, closed elm and the sessino hung. I tried to login
on another console and it hung right after the Password: prompt. I then
telnetted to a Sun running Solaris 2.4 on the same network as the 2.0.33
and it hung after the Password: prompt also. So I'm thinking about time
to head down and reboot my server... When I telneted into port 80 and 25
though everything seemed to be working fine.

Ok, I'm thinking maybe the 2.0.33 box isn't the prob. I look at syslog
messages on the 2.1.90 box and see this:

Mar 21 11:24:38 bengal kernel: TCPv4 bad checksum from 206.202.0.2:0017 to 206.202.2.150:0456, len=20/20/40
Mar 21 11:27:59 bengal kernel: TCPv4 bad checksum from 206.202.0.2:0017 to 206.202.2.150:0456, len=20/20/40
Mar 21 11:28:45 bengal kernel: TCPv4 bad checksum from 206.202.0.2:0017 to 206.202.2.150:0454, len=20/20/40
Mar 21 11:29:12 bengal kernel: TCPv4 bad checksum from 206.202.0.2:0017 to 206.202.2.150:045a, len=20/20/40
Mar 21 11:29:15 bengal kernel: TCPv4 bad checksum from 206.202.0.3:0017 to 206.202.2.150:045b, len=20/20/40
Mar 21 11:29:36 bengal kernel: TCPv4 bad checksum from 206.202.0.3:0017 to 206.202.2.150:045b, len=20/20/40

(0.2 is Linux server, 0.3 is Sun, 2.150 is Linux 2.1.90 btw)

The really weird thing was I discovered that what I was typing to these
apparently hung telnet sessions was being executed on the 2.0.33 server - I
just wasn't getting any of the response back. Well, just as I'm getting my
laptop(2.0.30) booted up on another phone line to see if it has a problem
and maybe get a tcpdump, it all starts working again (I know likely excuse
for not getting a dump.. what can I say :) Log into the 0.30 server - it
had no problems during the whole time period, logged me logging in and out
just like normal, only I couldn't see myself doing it of course on the 1.90
machine...

The 2.1.90 box is running ppp 2.3.3 btw, uptodate on all the necessary stuff
for 2.1.90. It is dialing into a 2.0.33 server running ppp 2.3.3 and of
course telnetting to a 2.0.33 server.

I realize this is limited use w/out a tcpdump but thought I should report
it anyway. Need any more info let me know.

Mitch

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