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From: pturner@ee.ogi.edu (Paul Turner)
Newsgroups: comp.unix.bsd.bsdi.misc
Subject: Can't get IP forwarding to work, need help
Date: 13 Jan 1997 20:54:48 -0800
Organization: Oregon Graduate Institute, Dept. of Electrical Engineering
Lines: 45
Message-ID: <5bf3io$sp@ee.ogi.edu>
NNTP-Posting-Host: ee.ogi.edu
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.bsdi.misc:5554

Hi,

We have 2 BSDI systems talking to each other via slip, the connection between
the two works just fine, but I can't get the machine connected to our subnet
to forward packets to the system on the other end of the connection. Given
that sys1 is on a subnet of our LAN and sys2 is connected via slip to sys1,
what is the magic need to make sys2 appear to be on the subnet of our LAN?
I've tried 'arp -s sys2IP sys1Ether' to get sys1 to grab packets for sys2,
but nothing happens. I've added a route on each machine that goes sys1 -> sys2
and sys2 -> sys1 - everything between the systems work just fine. 
Do I need to rebuild the kernel to turn on IP forwarding?
I noticed that there is a line in rc.local that appears to be important:

# to enable IP packet forwarding (routing):
# echo -n "IP forwarding: "; sysctl -w net.inet.ip.forwarding=1

Does this need uncommenting?

The kernel configuration for networking looks like:

# network options
options         INET                    # Internet: TCP/IP
# options       GATEWAY                 # IP routing
# options       "IPFORWARDSRCRT=0"      # disable forwarding of src-routed pkts
# options       NS                      # XNS
# options       ISO                     # ISO/OSI network
options         PPP                     # Point-to-Point Protocol
# options       CISCO_HDLC              # HDLC over sync serial
options         MULTICAST               # IP Multicast
# options       MROUTING                # Multicast agent forwarding multicast

Does the IP routing item need to be uncommented?

Any help would be appreciated.

Thanks,

--Paul  (pturner@ee.ogi.edu)


-- 
Paul J Turner,  Scientific Systems Administrator
Department of Electrical Engineering OGI
Email: pturner@ee.ogi.edu or pturner@teleport.com
Office: (503) 690-1109  http://www.ee.ogi.edu/~pturner