Date: Mon, 3 Feb 1997 00:16:02 GMT From: chris warth <csw@chezmoi.com> To: freebsd-questions@FreeBSD.ORG Subject: using route -interface Message-ID: <199702030016.AAA02120@ftp.chezmoi.com>
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Can someone please explain how to use the "-interface" option of the
"route" command? How do host routes installed via "-interface" differ
from routes learned from using default routes?
Specifically, I am running this test on 2.1.0-RELEASE and if I try to
use the "-interface" option to force traffic for a particular host out
through an interface, I cannot seem to ever get replies back. I
understand that this is usually used for ppp interfaces, but why won't
it work for simple ethernet interfaces as well? Do I need to do
something with proxy-arp?
In the simplest case, I have a machine connected to a single local
ethernet. Here is the output from "ifconfig -a"
de0: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet 206.26.48.2 netmask 0xffffff00 broadcast 206.26.48.255
lo0: flags=8009<UP,LOOPBACK,MULTICAST> mtu 16384
inet 127.0.0.1 netmask 0xff000000
At the beginning my routing table looks like this:
Routing tables
Internet:
Destination Gateway Flags Refs Use Netif Expire
default 206.26.48.1 UGSc 23 410 de0
127.0.0.1 127.0.0.1 UH 0 7 lo0
206.26.48 link#2 UC 1 0
206.26.48.1 0:c0:7b:0:1f:40 UHLW 12 3 de0 939
206.26.48.2 0:0:c0:96:9d:db UHLW 3 241 lo0
206.26.48.255 link#2 UHLW 1 822
224 link#2 UCS 0 0
206.26.48.1 is my gateway machine. 206.26.48.2 is the machine I am
on.
If I now delete the route for the gateway machine and replace it with
an explicit -interface route, I can no longer communicate with the
gateway at all.
# route delete 206.26.48.1
delete host 206.26.48.1
# route add 206.26.48.1 -interface 206.26.48.2
add host 206.26.48.1: gateway 206.26.48.2
Now this should be the same as it was before. I have just tried to
make explicit what was implied by the subnet mask before, namely, that
206.25.48.1 can be reached via interface de0. Yet now I cannot reach
206.26.48.1!
# ping 206.26.48.1
^C
--- 206.26.48.1 ping statistics ---
12 packets transmitted, 0 packets received, 100% packet loss
# netstat -rn
Routing tables
Internet:
Destination Gateway Flags Refs Use Netif Expire
default 206.26.48.1 UGSc 17 412 de0
10.100.100 link#3 UC 1 0
127.0.0.1 127.0.0.1 UH 0 7 lo0
206.26.48 link#2 UC 1 0
206.26.48.1 206.26.48.2 UHS 0 12 de0
206.26.48.2 0:0:c0:96:9d:db UHLW 3 281 lo0
206.26.48.255 link#2 UHLW 1 869
224 link#2 UCS 0 0
So I never received any replies to the ping, but the "Use" count for
that route did go up as expected. So why do the replies not get back?
Again, I am running this test on 2.1.0-RELEASE, but I have also seen
the same behavior on 2.1.5-RELEASE.
Thanks in advance for any help.
-csw
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