Problem with multiple virtual interfaces

I am having a problem with multiple virtual interfaces on a Linux
(slackware) box running kernel 2.4.22

The box is being used to host multiple FTP sites (hence multiple IP's on
the same subnet)

I have multiple interfaces configure as follow

eth0 xxx.xxx.xxx.48 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
eth0:1 xxx.xxx.xxx.49 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
eth0:2 xxx.xxx.xxx.50 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
eth0:3 xxx.xxx.xxx.51 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
eth0:4 xxx.xxx.xxx.52 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
eth0:5 xxx.xxx.xxx.53 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
eth0:6 xxx.xxx.xxx.54 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
eth0:7 xxx.xxx.xxx.55 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255


From a second machine I can ping everything execpt xxx.xxx.xxx.52. I
have removed and added the interface back. changed the order, put the
IP on a different interface. Switched the interface with another, but
it refuses to ping.

A tcpdump shows the following ...

tcpdump -n <host doing the ping>02:45:18.837306 IP 209.250.142.154 >
209.250.128.44: icmp 64: echo request seq 240
02:45:19.837932 IP yyy.yyy.yyy.yyy > xxx.xxx.xxx.52: icmp 64: echo
request seq 241
02:45:19.837932 IP yyy.yyy.yyy.yyy > xxx.xxx.xxx.52: icmp 64: echo
request seq 242
02:45:19.837932 IP yyy.yyy.yyy.yyy > xxx.xxx.xxx.52: icmp 64: echo
request seq 243
02:45:19.837932 IP yyy.yyy.yyy.yyy > xxx.xxx.xxx.52: icmp 64: echo
request seq 244


Why are there no echo respones ? The tcpdump for trying to ping any
other interface on the box does show the "echo response". I see the
same behavior with any other kind of attempt to reach the box. I see
requests coming in, but no responses going out

Any help appreciated.




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On Wed, 23 Jun 2004, Brian Laughton <(E-Mail Removed)> wrote:
> I am having a problem with multiple virtual interfaces on a Linux
> (slackware) box running kernel 2.4.22
>
> The box is being used to host multiple FTP sites (hence multiple IP's on
> the same subnet)
>
> I have multiple interfaces configure as follow
>
> eth0 xxx.xxx.xxx.48 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
> eth0:1 xxx.xxx.xxx.49 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
> eth0:2 xxx.xxx.xxx.50 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
> eth0:3 xxx.xxx.xxx.51 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
> eth0:4 xxx.xxx.xxx.52 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
> eth0:5 xxx.xxx.xxx.53 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
> eth0:6 xxx.xxx.xxx.54 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
> eth0:7 xxx.xxx.xxx.55 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
>
>
> From a second machine I can ping everything execpt xxx.xxx.xxx.52. I
> have removed and added the interface back. changed the order, put the
> IP on a different interface. Switched the interface with another, but
> it refuses to ping.

Maybe the host you are trying to ping from does not understand your
inconsistant netmask/broadcast. That netmask/broadcast pair would be for
network x.x.x.128 IPs from x.x.x.129 to x.x.x.254. For your IPs
(x.x.x.126 or lower) and that netmask, the broadcast would be x.x.x.127.

But maybe it is some other routing glitch. Does the output of
"/sbin/route -n" mention that IP or any other funky network/netmask pairs
that might accidently include it?

--
David Efflandt - All spam ignored http://www.de-srv.com/

David Efflandt wrote:
> On Wed, 23 Jun 2004, Brian Laughton <(E-Mail Removed)> wrote:
>
>>I am having a problem with multiple virtual interfaces on a Linux
>>(slackware) box running kernel 2.4.22
>>
>>The box is being used to host multiple FTP sites (hence multiple IP's on
>>the same subnet)
>>
>>I have multiple interfaces configure as follow
>>
>>eth0 xxx.xxx.xxx.48 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
>>eth0:1 xxx.xxx.xxx.49 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
>>eth0:2 xxx.xxx.xxx.50 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
>>eth0:3 xxx.xxx.xxx.51 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
>>eth0:4 xxx.xxx.xxx.52 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
>>eth0:5 xxx.xxx.xxx.53 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
>>eth0:6 xxx.xxx.xxx.54 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
>>eth0:7 xxx.xxx.xxx.55 netmask 255.255.255.128 broadcast xxx.xxx.xxx.255
>>
>>
>> From a second machine I can ping everything execpt xxx.xxx.xxx.52. I
>>have removed and added the interface back. changed the order, put the
>>IP on a different interface. Switched the interface with another, but
>>it refuses to ping.
>
>
> Maybe the host you are trying to ping from does not understand your
> inconsistant netmask/broadcast. That netmask/broadcast pair would be for
> network x.x.x.128 IPs from x.x.x.129 to x.x.x.254. For your IPs
> (x.x.x.126 or lower) and that netmask, the broadcast would be x.x.x.127.
>
> But maybe it is some other routing glitch. Does the output of
> "/sbin/route -n" mention that IP or any other funky network/netmask pairs
> that might accidently include it?
>
Correct broadcast to .255, still not working.

A tcpdump on the hosts machine does see the ping requests come in - it
just not replying to them on this one IP



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can you please print your routing table?


raqueeb hassan
congo (drc)