Re: dummy interface for pfinet

[Marcus Brinkmann]

On Sun, Oct 01, 2000 at 05:14:48PM -0400, Jeff Sheinberg wrote:
> Marcus Brinkmann writes:
> [snip]
>  > settrans /servers/socket/2 /hurd/pfinet -i dummy \
>  > -a 192.168.0.1 -m 255.255.255.0 -g 192.168.0.2
>  >
>  > The dummy interface is the same as the dummy interface in
>  > linux:  A bottomless pit. You don't get a single packet out of
>    ^^^^^^^^^^^^^^^^^^^^^^^^
>  > it, and everything you send to it is lost.
>  >
>  > Note that the above local address 192.168.0.1 is recognized as
>  > local.  Stuff sent to this address is not lost, of course.
> [snip]
> 
> Perhaps I misunderstand what you mean by `dummy interface', but on
> my linux box, the `dummy interface' is a loopback, not a bit
> bucket. 
> 
>     23 jeff ~ $ ifconfig -i dummy0
>     dummy0    Link encap:Ethernet  HWaddr 00:00:00:00:00:00  
>               inet addr:172.16.0.1  Bcast:172.16.255.255  Mask:255.255.0.0
>               UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
>               RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>               TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>               collisions:0 txqueuelen:0 
> 
>     24 jeff ~ $ telnet dummy0 smtp
>     Trying 172.16.0.1...
>     Connected to eden-hda7.my.local.
>     Escape character is '^]'.
>     220 eden-hda7.my.local ESMTP Postfix (Postfix-20000531-Snapshot)
>     helo dude
>     250 eden-hda7.my.local
>     quit
>     221 Bye
>     Connection closed by foreign host.

That's why I said that the address 172.16.0.1 is considered to be local.
It's the address of the dummy interface itself, so it is identical to the
loopback device.

Try addresses in the network range of the dummy interface, in your case
172.16.X.Y, which are NOT the address of the dummy interface itself (for
example, try 172.16.0.2). That's the bit bucket. Or put the gateway to
something in this range, and every address is sent to the bottomless pit.

Here is an example from Linux (wow, ifconfig speaks german):

ulysses:~# ifconfig -i dummy
dummy      Linkverkapselung:Ethernet  HWaddr 00:00:00:00:00:00
          inet addr:192.168.0.1  Bcast:192.168.0.255  Maske:255.255.255.0
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          Empfangene Pakete:0 Fehler:0 Weggeworfen:0 Überlauf:0 Rahmen:0
          Verschickte Packete:0 Fehler:0 Weggeworfen:0 Überlauf:0 Rahmen:0
          Kollisionen:0 Sendewarteschlangenlänge:0

ulysses:~# ping 192.168.0.1
PING 192.168.0.1 (192.168.0.1): 56 data bytes
64 bytes from 192.168.0.1: icmp_seq=0 ttl=255 time=0.1 ms
64 bytes from 192.168.0.1: icmp_seq=1 ttl=255 time=0.0 ms

--- 192.168.0.1 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 0.0/0.0/0.1 ms
ulysses:~# ping 192.168.0.2
PING 192.168.0.2 (192.168.0.2): 56 data bytes

--- 192.168.0.2 ping statistics ---
2 packets transmitted, 0 packets received, 100% packet loss


And it works identical on the Hurd.

Thanks,
Marcus

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