Why is my server responding to arp requests from the wrong interface on Red Hat Enterprise Linux ?

Solution Verified - Updated -

Issue

  • On a system with two NIC's, using arpwatch we observe the IP address changing over the network interfaces:

    arpwatch: new station 192.168.100.33 0:f:20:6b:b2:5arpwatch: new station 192.168.100.33 0:f:20:6b:b2:5
    arpwatch: changed ethernet address 192.168.100.33 0:f:20:6b:b2:4 (0:f:20:6b:b2:5)
    arpwatch: flip flop 192.168.100.33 0:f:20:6b:b2:5 (0:f:20:6b:b2:4)
    arpwatch: flip flop 192.168.100.33 0:f:20:6b:b2:4 (0:f:20:6b:b2:5)
    arpwatch: flip flop 192.168.100.33 0:f:20:6b:b2:5 (0:f:20:6b:b2:4)
    

Environment

  • Red Hat Enterprise Linux All version
  • Multiple network interfaces on different subnets

  • The kernel parameter 'ip_forward' may be set to '1' (not compulsary).

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