From: The Derfer on
I've got a RHEL 3AS box with a PCI-X network card in it and I've set
that up as such (its ifconfig -a here):

eth3 Link encap:Ethernet HWaddr 00:0A:5E:7A:E7:33
inet addr:10.156.30.176 Bcast:10.156.30.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:527 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:62674 (61.2 Kb) TX bytes:0 (0.0 b)
Interrupt:24

Its ifcfg-eth3 looks like:
# Broadcom Corporation|NetXtreme BCM5701 Gigabit Ethernet
DEVICE=eth3
ONBOOT=yes
BOOTPROTO=static
IPADDR=10.156.30.176
NETMASK=255.255.255.0
HWADDR=00:0A:5E:7A:E7:33

But when I assign my laptop the address 10.156.30.213 and try to ping
10.156.30.176
I can't successfully do it through a crossover cable and further get
these messages
in /var/log/messages. What's wrong here? Got to be a config issue (I
think):

Oct 2 12:13:41 host1 kernel: martian source 10.156.30.255 from
10.156.30.213, on dev eth3
Oct 2 12:13:41 host1 kernel: ll header: ff:ff:ff:ff:ff:ff:
00:15:c5:47:d2:72:08:00
Oct 2 12:14:50 host1 kernel: martian source 10.156.30.176 from
10.156.30.213, on dev eth3
Oct 2 12:14:50 host1 kernel: ll header: ff:ff:ff:ff:ff:ff:
00:15:c5:47:d2:72:08:06
Oct 2 12:14:55 host1 kernel: martian source 10.156.30.176 from
10.156.30.213, on dev eth3
Oct 2 12:14:55 host1 kernel: ll header: ff:ff:ff:ff:ff:ff:
00:15:c5:47:d2:72:08:06
Oct 2 12:15:00 host1 kernel: martian source 10.156.30.176 from
10.156.30.213, on dev eth3
Oct 2 12:15:00 host1 kernel: ll header: ff:ff:ff:ff:ff:ff:
00:15:c5:47:d2:72:08:06
Oct 2 12:15:06 host1 kernel: martian source 10.156.30.176 from
10.156.30.213, on dev eth3
Oct 2 12:15:06 host1 kernel: ll header: ff:ff:ff:ff:ff:ff:
00:15:c5:47:d2:72:08:06
Oct 2 12:15:47 host1 kernel: martian source 10.156.30.176 from
10.156.30.213, on dev eth3
Oct 2 12:15:47 host1 kernel: ll header: ff:ff:ff:ff:ff:ff:
00:15:c5:47:d2:72:08:06
Oct 2 12:15:56 host1 kernel: martian source 10.156.30.176 from
10.156.30.213, on dev eth3
Oct 2 12:15:56 host1 kernel: ll header: ff:ff:ff:ff:ff:ff:
00:15:c5:47:d2:72:08:06

Netmask on my laptop is 255.255.255.0
IP is 10.156.30.213
No gateway specified.

Routing table for linux host:

[root(a)host1 user]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref
Use Iface
1.1.1.0 * 255.255.255.0 U 0 0
0 eth2
10.156.30.0 * 255.255.255.0 U 0 0
0 eth0
10.156.30.0 * 255.255.255.0 U 0 0
0 eth3
default 10.156.30.1 0.0.0.0 UG 0 0
0 eth0

Please advise.
THANK YOU.
From: Burkhard Ott on
On Fri, 02 Oct 2009 14:00:24 -0700, The Derfer wrote:

> 10.156.30.0 * 255.255.255.0 U 0 0 0 eth0
> 10.156.30.0 * 255.255.255.0 U 0 0 0 eth3

Your networks are on both interfaces (eth0 and eth3).
From: The Derfer on
On Oct 2, 5:46 pm, Burkhard Ott <news2...(a)derith.de> wrote:
> On Fri, 02 Oct 2009 14:00:24 -0700, The Derfer wrote:
> >10.156.30.0    *              255.255.255.0  U     0      0 0 eth0
> >10.156.30.0    *              255.255.255.0  U     0      0 0 eth3
>
> Your networks are on both interfaces (eth0 and eth3).

What do I need to do? I don't understand your response.
From: David Schwartz on
On Oct 2, 3:58 pm, The Derfer <derf...(a)gmail.com> wrote:
> On Oct 2, 5:46 pm, Burkhard Ott <news2...(a)derith.de> wrote:
>
> > On Fri, 02 Oct 2009 14:00:24 -0700, The Derfer wrote:
> > >10.156.30.0    *              255.255.255.0  U     0      0 0 eth0
> > >10.156.30.0    *              255.255.255.0  U     0      0 0 eth3
>
> > Your networks are on both interfaces (eth0 and eth3).
>
> What do I need to do?  I don't understand your response.

Your routing setup is extremely weird. Your default route is:

default 10.156.30.1 0.0.0.0 UG 0 0
0 eth0

But if 10.156.30.0/24 is routed to eth3, how can 10.156.30.1 be
reachable through eth0 directly? You'd have to have some weird proxy
ARP setup. It looks like you have two network interfaces that are
configured as nonoverlapping networks, given IP addresses on
overlapping networks, and routed as non-overlapping networks.

If there's an ethernet network that corresponds to 10.156.30.0/24, it
needs to be connected to either eth0 or eth3. Otherwise, you need a
configuration that makes sense for two interfaces on the same IP
network, such as bridging.

DS
From: Burkhard Ott on
Am Fri, 02 Oct 2009 18:55:57 -0700 schrieb David Schwartz:

> On Oct 2, 3:58 pm, The Derfer <derf...(a)gmail.com> wrote:
>> On Oct 2, 5:46 pm, Burkhard Ott <news2...(a)derith.de> wrote:
>>
>> > On Fri, 02 Oct 2009 14:00:24 -0700, The Derfer wrote:
>> > >10.156.30.0    *              255.255.255.0  U     0      0 0 eth0
>> > >10.156.30.0    *              255.255.255.0  U     0      0 0 eth3
>>
>> > Your networks are on both interfaces (eth0 and eth3).
>>
>> What do I need to do?  I don't understand your response.
>
> Your routing setup is extremely weird. Your default route is:
>
> default 10.156.30.1 0.0.0.0 UG 0 0 0 eth0
>
> But if 10.156.30.0/24 is routed to eth3, how can 10.156.30.1 be
> reachable through eth0 directly?

First route match.

> You'd have to have some weird proxy ARP setup.

He haven't wrote that he set this kernel variable, so I assume he didn't
set it.


> If there's an ethernet network that corresponds to 10.156.30.0/24, it
> needs to be connected to either eth0 or eth3. Otherwise, you need a
> configuration that makes sense for two interfaces on the same IP
> network, such as bridging.

This setup as a bridge would be very funny and if your switch doesn't use
stp the fun swaps over to the switch too :-D.

cheers