On Sunday 29 October 2006 15:10, Herbert Xu wrote:
> On Sun, Oct 29, 2006 at 01:55:56PM +0100, Denis Vlasenko wrote:
> >
> > With "echo 1 >/proc/sys/kernel/panic_on_oops" I've got
> > what you're requested. See screenshot:
> >
> > http://busybox.net/~vda/gso_panic/forcedeth_gso_panic2.jpg
>
> Thanks!
>
> Please let me know if this patch fixes it:
>
> [NET]: Fix segmentation of linear packets
Okay, will test now.
> The fact that you're triggering this bug at all means that
> something else has gone wrong. First of all your picture
> shows a device setting of "lo". This does not tally with
> the fact that the BUG was triggered by ssh. Do you have
> any idea why this is the case? Do you have any netfilter
> rules that might cause this?
Yes, I have netfilter rules which redirect all outgoing
port 22 connections to local port 2222. I run tcpserver
on 2222 which spawns hose for each connection.
All this ugliness is required to get ssh working across
buggy D-Link router. It chokes on nagle-disabled sessions,
I think.
The rules:
# iptables -t nat -N redir22
# iptables -t nat -A redir22 -d 192.168.1.111 -j RETURN
# iptables -t nat -A redir22 -d 127.0.0.1 -j RETURN
# iptables -t nat -A redir22 --match owner --uid-owner daemon -j RETURN
# iptables -t nat -A redir22 -p tcp -j REDIRECT --to 2222
# iptables -t nat -A OUTPUT -p tcp --dport 22 -j redir22
---FILTER--
Chain INPUT (policy ACCEPT 20 packets, 1360 bytes)
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
Chain OUTPUT (policy ACCEPT 2 packets, 100 bytes)
---NAT-----
Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
Chain POSTROUTING (policy ACCEPT 1 packets, 60 bytes)
Chain OUTPUT (policy ACCEPT 1 packets, 60 bytes)
0 0 redir22 tcp -- * * 0.0.0.0/0
0.0.0.0/0 tcp dpt:22
Chain redir22 (1 references)
0 0 RETURN all -- * * 0.0.0.0/0
192.168.1.111
0 0 RETURN all -- * * 0.0.0.0/0
127.0.0.1
0 0 RETURN all -- * * 0.0.0.0/0
0.0.0.0/0 OWNER UID match 50
0 0 REDIRECT tcp -- * * 0.0.0.0/0
0.0.0.0/0 redir ports 2222
---MANGLE--
Chain PREROUTING (policy ACCEPT 2 packets, 100 bytes)
Chain INPUT (policy ACCEPT 2 packets, 100 bytes)
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
Chain OUTPUT (policy ACCEPT 2 packets, 100 bytes)
Chain POSTROUTING (policy ACCEPT 2 packets, 100 bytes)
On port 2222 I have the following running:
run:
====
ip=0.0.0.0
port=2222
user=daemon
maxconn=100
# envuidgid $user tcpserver -U:
# run tcpserver as $user
exec \
env - \
softlimit \
envuidgid $user \
tcpserver \
-U \
-v -R -H -l 0 -c $maxconn \
$ip $port \
./startproxy22
startproxy22
============
targetip="$TCPORIGDSTIP"
targetport=22
# Loop prevention
if test "$TCPLOCALIP" = "$targetip"; then
if test "$TCPLOCALPORT" = "$targetport"; then
env >loop.detected
exit 0
fi
fi
# netcat rulez... however hose of netpipes fame
# is still better because --netslave properly closes
# connection on input EOF.
exec env - hose "$targetip" "$targetport" --netslave
> If it is indeed lo, could you please check the ethtool -k
> setting on it? Also what is the ethtool -k setting on the
> interface where you expect ssh to go out?
# ethtool -k lo
Offload parameters for lo:
Cannot get device rx csum settings: Operation not supported
Cannot get device tx csum settings: Operation not supported
Cannot get device scatter-gather settings: Operation not supported
rx-checksumming: off
tx-checksumming: off
scatter-gather: off
tcp segmentation offload: off
--
vda
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