"multiple interfaces match the same subnet"



  • ok you pfsense gurus, help me out please, looking a the DHCP logs I found this

    pfsense "multiple interfaces match the same subnet"

    is it a problem?



  • @georgeberz:

    is it a problem?

    Deepnds on what you want to have happen.

    Apparently FreeBSD interfaces dc0 and rl0 are both on IP subnet 192.168.1.0/24. If a packet arrives on another interface and is destined for a system in 192.168.1.0/24 subnet on which interface should it be sent out? These interfaces should have separate subnets.

    Do you want to bridge the two interfaces?



  • Im assuming one should be the WAN and the other the LAN

    WAN = r10
    LAN = dc0

    ???



  • Then you probably want DHCP  server enabled on LAN but not WAN. It is not common to run DHCP server on WAN.

    What is connected to your WAN interface? Is the WAN interface supposed to have a static IP address (specified by ISP perhaps) or  is it supposed to get its IP address "on demand" from something connected to the WAN interface? If the latter, does it use PPPoE or DHCP? If DHCP then in the  web GUI: Interfaces -> WAN under heading General Configuration set Type to DHCP and save.



  • here is the interfaces>wan config




  • Then the PPPoE server has allocated your WAN interface an IP address in the same subnet as your LAN interface. You should change the LAN interface subnet to something else (e.g. 192.168.11.0/24 or 172.16.1.0/24) and reallocate the DHCP addresses accordingly.

    Or, if you have control of the PPPoE server, you could change the subnet it allocates.

    Actually there is something not quite right here. If you WAN interface is using PPPoE then its physical interface (rl0) shouldn't have an IP address. Maybe you have been changing the configuration (e.g. switched WAN from static to PPPoE) and you need a reboot to flush out the old configuration information. There are many things in pfSense that can be changed on the fly but its been my experience that some types of changes to interface IP addresses seem to need a reboot to correctly take effect.



  • yes, I had a static config, then I went to pppoe, then simply rebooting fixed the problem, I think :)

    Anyhow it is gone now…

    Thank you


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