Linux Packet Forwarding

Can linux forward packets back through the same interface they came?  If so, how can this be accomplished with routes?  Thanks.
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May be helpfull to get at least part of topology, but generally said, it is possible to route thru the same interface. If we do have two networks directly connected:
route add -net xx.xx.xx.0 netmask y.y.y.0 dev eth0
route add -net aa.aa.aa.0 netmask b.b.b.0 dev eth0

If there's gateway to one of the networks on the way, use
route add -net xx.xx.xx.0 netmask y.y.y.0 gw zz.zz.zz.zz

Don't forget to switch on packet forwarding
echo "1" > /proc/sys/net/ipv4/ip_forward

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Yes it can, use normal routing rules.
But mind, that if the connection gets SNATed or DNATed on the router as well - both actions are required SNAT and DNAT.
Oh, one more thing, linux by default does not route such packets, but sends redirect to the sending device (so it knows there shorter path). To disable this
for f in /proc/sys/net/ipv4/conf/*/send_redirects; do echo 0 > $f; done
MainStaySolutionsAuthor Commented:
Thank you for the quick response.
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