DHCP allowing double entries for a static IP address



  • We have DHCP static mappings within the network. I recently updated to pfSense 2.4.3-RELEASE-p1 (amd64) and I noticed that DHCP was allowing me to assign a MAC address to an IP address that has been already assigned. If remember right, the previous versions would flag me if there's a conflicting entry in the DHCP static mappings. FYI.


  • Rebel Alliance Developer Netgate

    There are use cases where someone may want to use multiple MACs for the same IP address, such as roaming between wired/wireless.

    It's been this way since 2.4.3: https://redmine.pfsense.org/issues/8220



  • I'm pleased to see this implemented actually as it frustrated me I couldn't do this before.

    Seems really pointless having different IP addresses for wired/wireless on my laptop when I will only be using one or the other at any given time. It makes any sort of traffic accounting for a machine awkward without it and wastes IP address space as both are never going to be in use at the same time.



  • @alex-atkin-uk said in DHCP allowing double entries for a static IP address:

    Seems really pointless having different IP addresses for wired/wireless on my laptop when I will only be using one or the other at any given time.

    I run Linux and don't have that problem. I just use the WiFi IP address. When connected via Ethernet, Linux forwards as appropriate. Windows doesn't. Linux uses a metric on the interfaces that cause traffic to prefer Ethernet over WiFi, when both are connected. Macs, based on BSD, might do similar, but I don't have one to check with.



  • The point is I never WANT WiFi and ethernet connected at the same time, because its either going to go out via WiFi making having it plugged in pointless, or its going over ethernet which would HAVE to use a different IP address to work.

    Granted having the same IP address can be a problem if you accidentally forget to disconnect WiFi before plugging in, but its a small price to pay for a better IP configuration.



  • @jimp said in DHCP allowing double entries for a static IP address:

    There are use cases where someone may want to use multiple MACs for the same IP address, such as roaming between wired/wireless.

    It's been this way since 2.4.3: https://redmine.pfsense.org/issues/8220

    Thank you. That clears that up.