arp entries for local interfaces disappearing ?

[Ruslan Ermilov]

On Wed, Apr 07, 2004 at 10:57:48AM -0700, Luigi Rizzo wrote:
> Can someone explain why, in my arp table, i don't have an
> entry for my local machine ? I just noticed this by chance,
> on my 4.9 box at the office, and now again at home:
> 
>     > ifconfig
>     rl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> 	    inet 10.0.1.55 netmask 0xffffff00 broadcast 10.0.1.255
> 	    inet 10.1.1.236 netmask 0xffffff00 broadcast 10.1.1.255
> 	    ether 00:40:f4:34:b1:4b
> 	    media: Ethernet autoselect (100baseTX <full-duplex>)
> 	    status: active
>     lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
> 	    inet 127.0.0.1 netmask 0xff000000 
>     > arp -na
>     ? (10.0.1.52) at 00:02:2d:08:a3:3b on rl0 [ethernet]
>     ? (10.0.1.64) at 52:54:05:de:99:7c on rl0 [ethernet]
>     > 
> 
> the interface is actually up and moving traffic -- the box is talking
> to 10.0.1.52.
> The route magically reappears if i try to open a session to the
> local box using the interface's address:
> 
>     > ssh 10.0.1.55
>       ... bla bla bla ...
>     > arp -na
>     ? (10.0.1.52) at 00:02:2d:08:a3:3b on rl0 [ethernet]
>     ? (10.0.1.55) at 00:40:f4:34:b1:4b on rl0 permanent [ethernet]
>     ? (10.0.1.64) at 52:54:05:de:99:7c on rl0 [ethernet]
> 
> and it's marked permanent, so it should not expire! Yet it
> looks like they do anyways...
> 
Here it doesn't disappear.  Perhaps, you have some routing daemons
running?  Or when it's parent route gets removed, it's deleted too,
for example, if you re-run ifconfig(8) on the interface.  Please
also note that if net.link.ether.inet.useloopback=1, the route is
actually through lo0 (route -vn get -host 10.0.1.55).


Cheers,
-- 
Ruslan Ermilov
ru at FreeBSD.org
FreeBSD committer
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