Question

4

Only one of my two network cards is working

rated 0 times [ 4] [ 0] / answers: 1 / hits: 3903 / 1 Year ago, tue, february 14, 2023, 12:09:18

I have a Ubuntu 10.04 LTS Server which has two Ethernet ports eth0 and eth1.

eth0 is connected to ISP1 with network 192.168.3.0/24 with server static address 192.168.3. 5

eth1 is connected to ISP2 with network 192.168.5.0/24 with server static address 192.168.5.10

When eth1 is connected, there is no internet connection from eth0. The internal network is accessible, eg, ssh , ping from other computers in 192.168.3.0/24 network.

When eth1 is disabled or disconnected, eth0 works just fine.

How can I ensure that both the Ethernet ports get internet connections?

netstat configs eth1 disabled

Kernel IP routing table



Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface



192.168.3.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0



0.0.0.0         192.168.3.1     0.0.0.0         UG        0 0          0 eth0

Netstat config eth1 enabled

Kernel IP routing table



Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface



192.168.3.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0



192.168.5.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1



0.0.0.0         192.168.5.254   0.0.0.0         UG        0 0          0 eth1



0.0.0.0         192.168.3.1     0.0.0.0         UG        0 0          0 eth0

Edit

I have also checked /etc/resolv.conf

There, I have manually added the nameserver for both the gateways.

ip addr show

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN 

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000

    link/ether 11:bb:3e:15:3e:0e brd ff:ff:ff:ff:ff:ff

    inet 192.168.3.100/24 brd 192.168.3.255 scope global eth0

           valid_lft forever preferred_lft forever

3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 100

    link/ether aa:2a:ae:5f:59:e8 brd ff:ff:ff:ff:ff:ff

    inet 192.168.5.100/24 brd 192.168.5.255 scope global eth1

           valid_lft forever preferred_lft forever

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ellter

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2 Years ago

answered 1 Year ago musining · Accepted Answer

I made a possible running example based on the basic implementation (of Split access) taken from here.

Create two additional routing tables, say T1 and T2.

ip route add 192.168.3.0/24 dev eth0 src 192.168.3.5 table T1

ip route add default via 192.168.3.0/24 table T1

ip route add 192.168.5.0/24 dev eth1 src 192.168.5.10 table T2

ip route add default via 192.168.5.0/24 table T2

Set up the main routing table:

ip route add 192.168.3.0/24 dev eth0 src 192.168.3.5

ip route add 192.168.5.0/24 dev eth1 src 192.168.5.10

Add your preference for default route:

ip route add default via 192.168.3.5

Set up the routing rules, choose what routing table to route with.

ip rule add from 192.168.3.5 table T1

ip rule add from 192.168.5.10 table T2

More info here.