Date: Thu, 27 Feb 2003 15:53:34 +0300 (MSK) From: "Alex L. Demidov" <alexd@vinf.ru> To: FreeBSD-gnats-submit@FreeBSD.org Cc: alexd@vinf.ru Subject: kern/48741: ipnat corrupts packets on gre interface with <rdr> rules Message-ID: <200302271253.h1RCrYU2006553@orlando.vinf.ru>
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>Number: 48741
>Category: kern
>Synopsis: ipnat corrupts packets on gre interface with <rdr> rules
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Feb 27 05:00:26 PST 2003
>Closed-Date:
>Last-Modified:
>Originator: Alex L. Demidov
>Release: FreeBSD 4.7-STABLE i386
>Organization:
Variant-Inform ISP
>Environment:
System: FreeBSD orlando.vinf.ru 4.7-STABLE FreeBSD 4.7-STABLE #13: Tue Jan 21 20:29:38 MSK 2003 root@orlando.vinf.ru:/.ftp/obj/.src/src/sys/ORLANDO i386
>Description:
When using ipnat <rdr> rules for redirecting packets incoming on gre
interface, ipnat replaces destination ip:port pair (right) and
swaps destination ip:port with source ip:port (?!).
>How-To-Repeat:
initialize gre tunnel
initialize ipnat
$ echo 'rdr gre0 0.0.0.0/0 port 80 -> ${server} port 3128 tcp' > ipnat.rules
$ ipnat -CF -f ipnat.rules
generate some traffice from host ${client} incoming to gre interface with destination port = 80.
$ tcpdump -v -i gre0 src host ${client} and dst port 80
and another instance of tcpdump
$ tcpdump -v -i ${primary_interface} src host ${server} and src port 3128 and dst host ${client}
You will see something like I captured today:
gre0: 1:50:31.024708 ${client}.4867 > ${somehost}.http: S [tcp sum ok] 2382677246:2382677246(0) win 8760 <mss 1460,nop,nop,sackOK> (DF) (ttl 125, id 60400, len 48)
xl0: 01:50:31.024771 ${server}.3128 > ${client}.4867: S [tcp sum ok] 175447728:175447728(0) ack 2382677247 win 57344 <mss 1460> (DF) (ttl 64, id 6641, len 44, bad cksum 0!)
gre0: 01:50:33.989896 ${client}.4867 > ${somehost}.http: S [tcp sum ok] 2382677246:2382677246(0) win 8760 <mss 1460,nop,nop,sackOK> (DF) (ttl 125, id 60402, len 48)
xl0: 1:50:33.989953 ${server}.3128 > ${client}.4867: S [tcp sum ok] 175447728:175447728(0) ack 2382677247 win 57344 <mss 1460> (DF) (ttl 64, id 6661, len 44, bad cksum 0!)
>Fix:
Don't know.
>Release-Note:
>Audit-Trail:
>Unformatted:
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