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misc/122685: It is not visible passing packets in tcpdump

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Sergey Zabolotny

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Apr 12, 2008, 5:24:28 AM4/12/08

to freebsd-gn...@freebsd.org

>Number: 122685
>Category: misc
>Synopsis: It is not visible passing packets in tcpdump
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sat Apr 12 09:30:02 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator: Sergey Zabolotny
>Release: 7.0
>Organization:
>Environment:
FreeBSD gw.deadnet.net 7.0-RELEASE FreeBSD 7.0-RELEASE #10: Fri Apr 11 20:47:03 EEST 2008 Zu...@gw.deadnet.net:/usr/src/sys/i386/compile/gw.deadnet.net i386

>Description:
There are two channels in the Internet. Default gateway through iface1.

There is a rule in firewall:

fwd ip_gw_iface2 ip from ip_iface2 to any out xmit iface1

do ping -S ip_iface1 mail.ru answers is, tcpdumpd shows sending requests and replays on the interface iface1.

do ping -S ip_iface2 mail.ru answers is, tcpdumpd shows only answers on the interface iface2. requests I do not see neither on iface1 nor on iface2.
>How-To-Repeat:
ifconfig fxp0 inet 192.168.1.254/24
ifconfig fxp1 inet 192.168.2.254/24
route add default 192.168.1.1

ipfw add 1 fwd 192.168.2.1 ip from 192.168.2.254 to any out xmit fxp0
ipfw add 2 allow ip from any to any

ping -S 192.168.2.254 mail.ru >/dev/null &

tcpdump -ni fxp1 icmp
tcpdump -ni fxp2 icmp
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:

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