Bug 4879 - Telnet from RH6 to 3Com Office Connect routers.
Telnet from RH6 to 3Com Office Connect routers.
Product: Red Hat Linux
Classification: Retired
Component: telnet (Show other bugs)
i386 Linux
medium Severity medium
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Assigned To: Florian La Roche
Depends On:
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Reported: 1999-09-03 05:32 EDT by chrisgorringe
Modified: 2008-05-01 11:37 EDT (History)
0 users

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2000-02-16 08:07:42 EST
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RHEL 7.3 requirements from Atomic Host:
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Description chrisgorringe 1999-09-03 05:32:35 EDT
I am posting this here because RH Installation support
suggest that it may be a bug.

My original posting is this:-

With Redhat 5.1 and 5.2, we have no problem telneting to
3Com Office Connect routers. With 6.0, we can telnet to
other hosts but not to 3Com OC routers. We have tried 3
different routers and 4 different installations of RH 6.0.

Using a packet analyzer, the problem looks like the fact
that the structure of the SYN packet to start the
conversation is larger on 6.0 than 5.x. On 6.0, the
diffences appear to be that the SYN flag is a Handshake
Request (A002) and a larger number of Option bytes and on
5.x, the SYN flag is a Handshake Request (6002) and only 4
byes of Option data.

I have included the two packet traces; the one with just a
single packet is the RedHat 6.0 - it repeats the packet a
number of times, and the other one is from RedHat 5.1.

Can you tell me what I need to change to get this to work.
We have the latest firmware versions in the 3Com boxes
Comment 1 Bernhard Rosenkraenzer 2000-02-16 08:07:59 EST
Does the new telnet version in rawhide (or the 6.2 beta) fix this?
Comment 2 Jeff Johnson 2000-07-27 16:20:46 EDT
Closed for lack of input.
Comment 3 chrisgorringe 2000-07-27 17:02:37 EDT
The problem is caused by the tcp_timestamps in /proc/sys/net/ipv4. 3Com routers 
cannot handle timestamped ip packets. By disabling this, you can successfully 
telnet a 3Com router. However, 3com don't really make routers any more.

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