IPv4: ssh failure, local port 1023

Geert Uytterhoeven (Geert.Uytterhoeven@cs.kuleuven.ac.be)
Tue, 1 Dec 1998 19:20:03 +0100 (CET)

Sometimes I have problems using ssh to log in. The ssh connection just doesn't
seem to succeed. Using the `-v' option, the last line it prints is

Allocated local port 1023

If I CTRL-C and retry, it fails again (reproducible). However, if I retry
without breaking the first attempt, ssh gets allocated a different local port
number and the connection succeeds.

The sshd runs on a Pentium with 2.0.35, ssh client runs on a 68040 with

But I've been seeing this on different types of machines, running both
Linux/m68k and Linux/ia32, with both 2.0.x and 2.1.x kernels, since more than a
year. There seems to be one common thing in the failures: the allocation of
the local port 1023. It doesn't always fail if the local port is 1023, but if
it fails, it's always 1023.

Needless to say, this is hard to track. Just when I wanted to start using
tcpdump, I couldn't reproduce the problem anymore :-(

Could this be related to a (possible) bug in the m68k IPv4 checksum code?
But then, the first time I saw the problem, it was between two ia32 boxes
running 2.0.x, more than one year ago.

Anyone with a clue? Thanks!



Geert Uytterhoeven                     Geert.Uytterhoeven@cs.kuleuven.ac.be
Wavelets, Linux/{m68k~Amiga,PPC~CHRP}  http://www.cs.kuleuven.ac.be/~geert/
Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium

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