DHCP server woes



  • 2.3.2 Release.  Everything was working up until last night, all I did change-wise was add a few static IP mappings to the DHCP server.

    Many of my DHCP-driven devices are getting an address outside the assigned range, specifically, several devices are getting addresses that are specifically mapped to other devices, creating an IP address conflict.  Even when only one device is powered on (ie, to remove the conflict), that devices connects to the network, gets an address, but then cannot access the internet.

    I'm at a loss here.  I've never had any issues before.  I am 100% certain there are no rogue DHCP servers on the network (small home network).

    Any advice would be great.

    Thanks.


  • Rebel Alliance Global Moderator

    As to getting outside pool.. Yeah that is how your reservations would work..Since you stated you creates static mappings.

    As to mapped to other devices..  Yeah that seems unlikely.

    What does your dhcp log show?  A sniff on pfsense diag, packet capture for port 67 will log all your dhcp traffic.  Now open that in wireshark - or post it here and we can take a look to what is happening..



  • Let me explain a little better and see if this help.

    I have a few clients with static IP addresses, and a few clients that are assigned via DHCP (wireless devices) that are statically mapped to always get the same address, based on MAC address.  Then, I have a pool set aside for other clients (guests, again this is a home network, or random computers that I bring up from time to time for testing).

    Let's say PC 1 is 10.0.0.2, PC 2 is 10.0.0.3, and Laptop 1 is 10.0.0.4.  And let's say my address pool for hosts pfsense doesn't recognize is 10.0.0.50-60.

    Well, pfsense likes to assign Laptop 1 as 10.0.0.5.  Which is reserved for another host via MAC static mapping, and is also outside the pool for unrecognized hosts.

    Having said that, if the host that is typically 10.0.0.5 is turned off, ie, there is no IP address conflict when pfsense gives that address to Laptop 1, Laptop 1 can't access the internet, or ping pfsense.  But it can ping other hosts on the network.



  • First thing I would do is check the IP pool numbers.  Maybe it starts at '5' instead of '50' ?  Just checking.

    Maybe change your Pool to say "70-80".


  • Rebel Alliance Global Moderator

    I you have a machine set static to .5 and a reservation for some other machine for .5 as well..  Then yeah your going to have issues.

    While dhcp servers can try and see if an IP is in use, via ping - if there is a lease for something and it asks for it - it normally will get it.

    If your devices are not getting their reservations then you have the mac wrong, or there is a different dhcp server or they have another lease they are renewing.



  • … and as usual, the DHCP server log will show what MAC pfSense is receiving - if it's in the "static lease map", the related IP will be proposed, otherwise one of the pool will be taken.