Re: telnet to vlan device fails

On Thu, 08 Sep 2005 10:05:25 -0700
Ben Greear <[email protected]> wrote:

> Alex Zeffertt wrote:
> > Hi list,
> > 
> > I've discovered a strange problem.  I've got two hosts with tagged interfaces called eth0.5.
> > When I try to telnet from host1 to host2 the session hangs where it should print out "Login:". 
> > I have no problems pinging host2 from host1 - even if I use max payload frames!
> > 
> > I've run tcpdump -i eth0.5 on host1 when trying to telnet to host2, and I've copied the output
> > to the end of this email.  It would seem that host2 (192.168.5.254) responds okay to the initial
> > SYN with a SYN/ACK.  host1 (192.168.5.1) then sends some data and host2 then correctly ACKs
> > this. But then host2 starts sending packets which have the first 10 bytes stripped!
> > 
> > I don't know why host2 is sending these packets.  However, it *is* running old software
> > (linux-2.4.4) and I have found that if I replace it with a host running later software
> > (linux-2.4.25) and create eth0.5 on this new host, then I have no problem telnetting into it.
> 
> The vlan code in 2.4.4 is probably crufty as hell...it was not even officially in the
> kernel untill 2.4.15 or so...
> 
> If you really need to use a kernel that old, I'd back-port the VLAN code from the latest 2.4
> kernel.
> 
> Ben
>

Hi Ben,

Looking back through our CVS logs it appears that it was the vlan.1.5 patch that I applied.  Do you
think this particular release is "crufty"?  :-p

I'll have a go at backporting, like you say.  Here goes... deep breath...

Alex