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icmp bug in 2.4.5?

To: <netdev@xxxxxxxxxxx>
Subject: icmp bug in 2.4.5?
From: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxxxxxx>
Date: Fri, 31 Aug 2001 13:40:16 +0200 (CEST)
Sender: owner-netdev@xxxxxxxxxxx
Hello,

After upgrading a firewall which is configured with connection tracking
from 2.4.2 to 2.4.5, the following strange thing happens on it:

traceroute targeted to the firewall completes successfully:
        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0) in
        udp.c generates proper (large enough) response packets, which
        then can be handled by the connection tracking code.

traceroute going through the firewall doesn't generate "proper"
        ICMP packets from the firewall:
        icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0) in
        ip_forward.c seems to generate too short packets, which cannot
        therefore be tracked:

Aug 31 12:16:12 zzz kernel: denied: IN= OUT=eth1 SRC=zzz.zzz.zzz.zzz
DST=a.b.c.d LEN=66 TOS=0x00 PREC=0xC0 TTL=255 ID=10383 PROTO=ICMP
TYPE=11 CODE=0 [SRC=a.b.c.d DST=x.y.z.w LEN=38 TOS=0x00
PREC=0x00 TTL=1 ID=42915 PROTO=UDP INCOMPLETE [6 bytes] ]

Nothing else's changed, only an upgrade happened.

Is it a known bug? If yes, is it fixed in later releases?

Regards,
Jozsef
-
E-mail  : kadlec@xxxxxxxxxxxxxxxxx, kadlec@xxxxxxxxxxxxxxx
WWW-Home: http://www.kfki.hu/~kadlec
Address : KFKI Research Institute for Particle and Nuclear Physics
          H-1525 Budapest 114, POB. 49, Hungary


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