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Date:      Mon, 2 Feb 1998 16:04:30 -0500
From:      "Cambria, Mike" <MCambria@lucent.com>
To:        "'freebsd-questions@freebsd.org'" <freebsd-questions@FreeBSD.ORG>
Subject:   2.2.5 and routed ICMP redirects.
Message-ID:  <D7014D55F851D0118203080009DCE8F1432B7E@SNOOPY>

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Hi,

Does FreeBSD send ICMP redirects when it is setup as a router?

I'm running FreeBSD 2.2.5 from the CDROM on 3 systems in our lab.  The 3
systems are connected via 2 Ethernet segments.  One of the systems is
connected to both Ethernet segments and routes between the two segments.
However, *all* systems are running "routed -s".

BSD1 ---------- BSD2 ---------- BSD3

Things worked fine, so we started expanding.  On the Ethernet segment
used between BSD1 and BSD2, a router was added to access the corporate
net (and the Internet.)

         R
         |
BSD1 ---------- BSD2 ---------- BSD3

BSD1 also has a default route configured to use BSD2.  BSD1 also has a
net/subnet route created for it by ifconfig.

When BSD1 pings the IP address of the router R, future packets go
directly to the router R.

Running the "route -n monitor" command in another window also says that
a redirect happened.  A (host) entry is also added to the routing table
of BSD1 for the router (shown via netstat -rn).  The netstat entry for
router R has flags of 'UHLW'  I believe that this is a result of the
destination IP address matching the net/subnet entry in the routing
table and the "host" R is cloned.  Tcpdump on the LAN segment doesn't
show an ICMP redirect message.

The default route is still set to BSD2.  This netstat entry has flags of
'UGSc'.  The netstat entry for the net/subnet entry created by ifconfig
for this subnet is 'UC'

When BSD1 pings to something on the corporate network (accessed via
router R), there is *no* ICMP redirect from BSD2.  Traffic goes from
BSD1 through BSD2 to router R.  Traceroute confirms this.

Shouldn't routed be sending ICMP redirect messages from BSD2 to BSD1?

Thanks,
MikeC

Michael C. Cambria                        Lucent Technologies
Member of Technical Staff                        Bell Labs Innovations
   Voice: (978) 287 - 2807                300 Baker Avenue
     Fax: (978) 287 - 2810                Concord, Massachusetts 01742
Internet:  mcambria@lucent.com




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