can't ping over crossover cable (get martian source)...

Main Page | Report this Page

Linux Forum Index » Linux - Red Hat Forum » can't ping over crossover cable (get martian source)...

Page 1 of 1

can't ping over crossover cable (get martian source)...

Author

Message

The Derfer...

Posted: Fri Oct 02, 2009 11:00 am

Guest

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 at (no spam) 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.

The Derfer...

Posted: Fri Oct 02, 2009 12:58 pm

Guest

On Oct 2, 5:46 pm, Burkhard Ott <news2... at (no spam) derith.de> wrote:

Quote:

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.

Burkhard Ott...

Posted: Fri Oct 02, 2009 3:46 pm

Guest

On Fri, 02 Oct 2009 14:00:24 -0700, The Derfer wrote:

Quote:

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).

David Schwartz...

Posted: Fri Oct 02, 2009 3:55 pm

Guest

On Oct 2, 3:58 pm, The Derfer <derf... at (no spam) gmail.com> wrote:

Quote:

On Oct 2, 5:46 pm, Burkhard Ott <news2... at (no spam) 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

Burkhard Ott...

Posted: Fri Oct 02, 2009 8:08 pm

Guest

Am Fri, 02 Oct 2009 18:55:57 -0700 schrieb David Schwartz:

Quote:

On Oct 2, 3:58Â pm, The Derfer <derf... at (no spam) gmail.com> wrote:
On Oct 2, 5:46Â pm, Burkhard Ott <news2... at (no spam) derith.de> wrote:

On Fri, 02 Oct 2009 14:00:24 -0700, The Derfer wrote:
10.156.30.0Â Â * Â Â Â Â Â Â Â 255.255.255.0Â U Â Â 0 Â Â Â 0 0 eth0
10.156.30.0Â Â * Â Â Â Â Â Â Â 255.255.255.0Â U Â Â 0 Â Â Â 0 0 eth3

Your networks are on both interfaces (eth0 and eth3).

What do I need to do? Â 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.

Quote:

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.

Quote:

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 Very Happy

.

cheers

David Schwartz...

Posted: Sat Oct 03, 2009 12:50 pm

Guest

On Oct 2, 11:08 pm, Burkhard Ott <news2... at (no spam) derith.de> wrote:

Quote:

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 Very Happy

I think his eth0 goes to a LAN of some kind and his eth3 is a
crossover cable to a machine not connected to the LAN. But it's hard
to be sure. If the machine at the end of the crossover cable is also
bridging and also connected to the LAN, and the LAN switch doesn't do
STP, then yes, it would be very funny.

DS

The Derfer...

Posted: Sat Oct 03, 2009 7:10 pm

Guest

eth0 does go to a LAN.
Where does this leave me?
Can't I make up any non-routable address of the type 10.156.30.x (x
not the same as
for eth0) for eth3? And so long as the laptop at the other end of the
crossover
cable also has a 10.156.30.x address (or does that technically
matter?) it ought
to be pingable ... right? Correct me where I'm wrong; I want this to
work AND
learn how to do it right.

Thank you.

On Oct 3, 6:50 pm, David Schwartz <dav... at (no spam) webmaster.com> wrote:

Quote:

On Oct 2, 11:08 pm, Burkhard Ott <news2... at (no spam) derith.de> wrote:

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 swapsoverto the switch too Very Happy

.

I think his eth0 goes to a LAN of some kind and his eth3 is acrossovercable to a machine not connected to the LAN. But it's hard
to be sure. If the machine at the end of thecrossovercable is also
bridging and also connected to the LAN, and the LAN switch doesn't do
STP, then yes, it would be very funny.

DS

Pascal Hambourg...

Posted: Sun Oct 04, 2009 3:46 am

Guest

Hello,

The Derfer a écrit :

Quote:

Can't I make up any non-routable address of the type 10.156.30.x

[These addresses are routable, on a private network. They are just not
routed on the public internet.]

Quote:

(x not the same as for eth0) for eth3?

Short answer : no, you can't have the same IP subnet on separate
ethernet segments. This is the basic of IP addressing and routing.

Also, you get "martian source" messages because rp_filter is enabled on
the interfaces.

Jan Gerrit Kootstra...

Posted: Sun Oct 04, 2009 3:58 am

Guest

Pascal Hambourg schreef:

Quote:

Hello,

The Derfer a écrit :
Can't I make up any non-routable address of the type 10.156.30.x

[These addresses are routable, on a private network. They are just not
routed on the public internet.]

(x not the same as for eth0) for eth3?

Short answer : no, you can't have the same IP subnet on separate
ethernet segments. This is the basic of IP addressing and routing.

Also, you get "martian source" messages because rp_filter is enabled on
the interfaces.
The Derfer,

Put a IP-address in a range that is not used at your Linux PC or some
where else on your companies net.

Like a 10.x.y.3 on eth3 and 10.x.y.4 on the laptop where x.y is unique.

Kind regards,

Jan Gerrit

David Schwartz...

Posted: Sun Oct 04, 2009 4:10 pm

Guest

On Oct 4, 2:46 am, Pascal Hambourg <boite-a-s... at (no spam) plouf.fr.eu.org>
wrote:

Quote:

Short answer : no, you can't have the same IP subnet on separate
ethernet segments. This is the basic of IP addressing and routing.

Well, you can, but you have to bridge them. It won't just magically
work. (And you wouldn't want it to bridge automatically!)

DS

chuck smoko...

Posted: Sun Oct 04, 2009 8:08 pm

Guest

Hi,
I don't see a RUNNING (i.e. UP BROADCAST RUNNING) on the interface's
ifconfig. Below is an ifconfig's eth0 on my system. From my
experience, if you don't have RUNNING, you don't have "link".

[root at (no spam) drlin001 sbin]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:06:5B:ED:39:38
inet addr:10.151.10.58 Bcast:10.151.10.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:426778132 errors:0 dropped:0 overruns:0 frame:0
TX packets:430171885 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:381827976 (364.1 MiB) TX bytes:2592226465 (2.4 GiB)
Base address:0xcce0 Memory:feb60000-feb80000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:165487055 errors:0 dropped:0 overruns:0 frame:0
TX packets:165487055 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:64638175 (61.6 MiB) TX bytes:64638175 (61.6 MiB)

[root at (no spam) drlin001 sbin]#

As I can't see your dmesg output, if the interfaces are GIGE, you don't
even need a crossover cable. Of all of the ones that I have seen, GIGE
Ethernet interfaces generally know how to auto-crossover. If you’re not
sure which physical interface is eth0 and which is eth1 (or eth2), run:

ethtool -p eth0 5

This blinks the LED on the interface for five seconds without
interrupting network traffic.

Chuck Smoko

The Derfer wrote:

Quote:

Pascal Hambourg...

Posted: Mon Oct 05, 2009 2:41 am

Guest

David Schwartz a écrit :

Quote:

On Oct 4, 2:46 am, Pascal Hambourg <boite-a-s... at (no spam) plouf.fr.eu.org
wrote:

Short answer : no, you can't have the same IP subnet on separate
ethernet segments. This is the basic of IP addressing and routing.

Well, you can, but you have to bridge them.

Then they become parts of the same segment, and the assertion remains
true. (Maybe "segment" is not the most appropriate term, "link layer" or
"broadcast domain" may be more accurate)

Page 1 of 1

All times are GMT - 5 Hours The time now is Mon Nov 30, 2009 8:25 am Linux Forum Index