Dhcp failover with non-pfSense machine



  • Hi,

    searching the web, I understand that the DHCP server in pfSense is the ISC dhcp server. I'm also running one on my Ubuntu machine, and would like to activate the one on pfSense, too, with both running as a failover team.

    On pfSense's GUI, I only find a field to enter a failover IP. The GUI also says there that CARP is needed as well. I searched the web some more, and found out that this specific field appears to be used with pfSense's failover in mind, where primary, secondary, etc. will be set "automatically" on two pfSense.

    I guess I could change dhcp.conf manually to implement dhcp failover with my Ubuntu machine. Anything I would break by doing this? E.g., could I still use the pfSense GUI (except for the failover IP field) to configure other aspects?

    Thanks!


  • LAYER 8 Global Moderator

    Out of curiosity is this a production/work network, home setup/lab?  What exactly are you wanting to run failover for?  Simple no brainer way to run dhcp a sort of failover is just just run 2 dhcp servers splitting the scope of the network range they provide.

    Client doesn't really care who provides it the dhcp.. It just going to grab lease from the one that answers first.  If the that first one fails, then when the lease expires it would send out a new discover and get an answer from the 2nd one, etc.  Only thing that would change is now the dhcp client would change to IP in the 2nd half of the pool.

    But this is rarely something that would need to be run in any sort of home network..  Prob just be better to setup an alert that your dhcp server is down, so that you would have time to fix it before client expires.  Only clients that would have issues should normally be new clients trying to get dhcp while your dhcp is down, etc.



  • Well, I just realized when my dhcp server machine went down, that I have a lot of services redundant or in failover mode, but unfortunately not dhcp. So I was looking for an easy way to do it, and one option was the pfSense machine (where I quickly put up a dhcp server with another address range as a quick fix).

    Since I had that running, I wondered if I couldn't just use it on a more permanent basis. I understand from your reply, however, that the pfSense implementation was not meant for this. So I'll probably just take some other machine already running here.

    Yes, it's something you shouldn't need for a home setup. Unless you are the only one who can fix such things in a family, and if you're at the same time away frequently for days or weeks even. And leaving the family with no working IT is not always something they appreciate.


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