Routing problem : two interfaces one gateway


 
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# 1  
Old 10-09-2014
Routing problem : two interfaces one gateway

hi folks,

i have a horstbox-router with the following configuration.

it has 4 ethernet ports from wich one (wan0) is configured as an external modem via dhcp. at this port/interface(wan0) it is connected with my home network (other switch).

this configuration results in the following routing table :

Code:
route 

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.2.0     *               255.255.255.0   U     0      0        0 br0
192.168.2.0     *               255.255.255.0   U     0      0        0 wan0
default         192.168.2.1     0.0.0.0         UG    0      0        0 wan0

so the router has internal acces to internet and can use voip from lan port 1 (wan0) which is the connected with a cable to my home network.

but on the other lan-ports i don't have internet acces or even acces to my home network. because it has no default gateway ?!

what command can i use to connect the interfaces br0 and wan0. or is it possible to route the traffic from br0 to wan0 ?

thanks in advance

Last edited by gencaslan; 10-09-2014 at 04:42 PM..
# 2  
Old 10-09-2014
"connect" how? What do you want sent from what to where? How will it manage to forward anything to anyone without a gateway?
# 3  
Old 10-09-2014
this is the horstbox

Image

there are 4 blue ethernet ports. i am sorry but i have no deep knowledge in ip.

the first lan port (wan0 interface) is connected to my home network like i noticed before. if i connect with putty to the router on a shell i can ping an internet address. so the traffic seems to go over the wan0 interface and the standard gateway 192.168.2.1. thats good and ok.

but if i connect another device on lan port 2 -4 (br0) it gets no ip address from dhcp. there is no connection to my home network.

i am not sure what is the solution to this problem because of my limited knowledge to ip.


but the solution to me should be that when i connect another device to lan port 2-4 (br0) it should get acces to my home network (dhcp, internet etc).

any ideas ?
# 4  
Old 10-09-2014
But if no interfaces have a default gateway, how can any information get anywhere?
# 5  
Old 10-09-2014
Quote:
Originally Posted by Corona688
But if no interfaces have a default gateway, how can any information get anywhere?
Code:
route 

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.2.0     *               255.255.255.0   U     0      0        0 br0
192.168.2.0     *               255.255.255.0   U     0      0        0 wan0
default         192.168.2.1     0.0.0.0         UG    0      0        0 wan0

as you can see the interface wan0 has a default gateway. 192.168.2.1 is my cable-network-router.

as far as i can see it is not possible to add a second default gateway (for the other lan-ports 2-4).
# 6  
Old 10-09-2014
If you wanted your router to route, you would have its IP address be the gateway for the things behind it.

If you don't want it to do any routing at all and just join all the ports together in a big virtual switch, make them all part of br0. Note that firewall rules still apply to traffic forwarded over a bridge.
# 7  
Old 10-11-2014
i found out that there is the command brctl. it was in another directory which was not in the path. the output is the following.

Code:
# ./brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.001b11b444de       no              eth1

again the output of route is

Code:
# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.2.0     *               255.255.255.0   U     0      0        0 br0
192.168.2.0     *               255.255.255.0   U     0      0        0 wan0
default         192.168.2.1     0.0.0.0         UG    0      0        0 wan0

ip route show delivers
Code:
# ./ip route show
192.168.2.0/24 dev br0  proto kernel  scope link  src 192.168.2.4
192.168.2.0/24 dev wan0  proto kernel  scope link  src 192.168.2.127
default via 192.168.2.1 dev wan0

ip link show delivers

Code:
# ./ip link show
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: MEI_PHY: <UP> mtu 0 qdisc noop
    link/[94]
3: eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
    link/ether 00:1b:11:b4:44:dd brd ff:ff:ff:ff:ff:ff
4: eth1: <BROADCAST,MULTICAST,PROMISC,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:1b:11:b4:44:de brd ff:ff:ff:ff:ff:ff
5: gre0@NONE: <NOARP> mtu 1476 qdisc noop
    link/gre 0.0.0.0 brd 0.0.0.0
6: br0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue
    link/ether 00:1b:11:b4:44:de brd ff:ff:ff:ff:ff:ff
7: wifi0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 199
    link/ether 00:19:5b:ed:63:44 brd ff:ff:ff:ff:ff:ff
8: wan0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 0a:1b:11:b4:44:de brd ff:ff:ff:ff:ff:ff
#

i think i need to remove br0 and bridge wan0 to eth1. but i am not sure.

again wan0 is the ehternet port which is connected to my homenetwork (switch).

if i try to remove the interface from the bridge br0 i loose my ssh-connection to the router. so this is no option. removing the bridge does not work because it is denied by brctl. i am a little stuck right now because of my limited knowledge to ip.

i repeat myself but with the recent permanten configuration the internal sip-telephony which needs access to internet works. for a solution i need a simple command that i can enter from the console to use the lan2-4 ports.
any ideas ? thx in advance.

Last edited by gencaslan; 10-11-2014 at 07:49 PM..
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