can't ping over crossover cable (get martian source)
in [Linux Networking]
|
Prev: Ping domain name vs nslookup IP
Next: GRE Keys
From: Burkhard Ott on 3 Oct 2009 02:08 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
From: David Schwartz on 3 Oct 2009 18:50 On Oct 2, 11:08 pm, Burkhard Ott <news2...(a)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 swaps over to the switch too :-D. 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
From: The Derfer on 4 Oct 2009 01:10 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...(a)webmaster.com> wrote: > On Oct 2, 11:08 pm, Burkhard Ott <news2...(a)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 :-D. > > 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
From: Pascal Hambourg on 4 Oct 2009 05:46 Hello, The Derfer a �crit : > 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.
From: Jan Gerrit Kootstra on 4 Oct 2009 05:58
Pascal Hambourg schreef: > 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 |