One network adapter is responding for all the others

Question

All network traffic to 192.168.1.66 & 192.168.1.53, is going to the enp3s0.

The only way to have each adapter independent is to put them on different subnets.(e.g. 192.168.2.20, 192.168.1.20) I don't think I should have to do that.

The system has the following devices:

enp1s0    Link encap:Ethernet  HWaddr a0:36:9f:9f:15:ec  
          inet addr:192.168.1.66  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::753b:a97e:5882:b357/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:713 errors:0 dropped:0 overruns:0 frame:0
          TX packets:60 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:121263 (121.2 KB)  TX bytes:7422 (7.4 KB)

enp3s0    Link encap:Ethernet  HWaddr a0:36:9f:47:fb:70  
          inet addr:192.168.1.53  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::929b:3d49:487f:80b9/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:3469195256 errors:0 dropped:0 overruns:0 frame:0
          TX packets:651156361 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:5252359698306 (5.2 TB)  TX bytes:43082585566 (43.0 GB)

sending an ARP from another machine to 192.168.1.66 is responded to by MAC ::70. So basically the traffic is going to enp3s0. Its important to note that enp3s0 is the default iface for route.

Anyone know how to fix this?

Answer 1

This is normal network behavior. Your system will respond to ARP requests for any IP it supports on any interface. There are two options:

• Channel bonding, where the two interfaces are treated as one, and traffic flow equally.
• Route marking and filtering to ensure traffic for each interface is routed accordingly.

Outgoing connections will be routed according to the routing table. The source address depends on the source IP address the connection is bound to. This normally is the IP address of the interface. Responses to ARP requests generally follow the same routing rules as for any other traffic.

You could try using gratuitous ARP packets to announce the desired MAC address for the second IP address. You may need to periodically do the announcements.