pfsense dhcp server not issuing addresses from requesters with an ip address



  • My pfSense (latest download) was not issuing IP’s to some machines. I found, through the DHCP Server log, that if the client already had an IP, it would not respond.

    Doing an “ipconfig /release”, or “ipconfig /release <connection name>” didn’t actually remove the stale IP, what I had to do was a “ipconfig /release *”, before pfSense would respond and assign an IP.

    Three questions:

    1. Is the correct response from a DHCP Server?
      2. If so, then why do my other “Router/DHCP Servers” respond?
      3. If not, then is this a “bug” in pfSense?

    Thanks, for any insight you may have.

    Mike


  • LAYER 8 Global Moderator

    what was the response from pfsense exactly? Was the client sending a discover or a request for some OLD ip that was from a different network?

    If the client asks for renew and the lease is not 50% over the server were tell the client your fine, etc.

    Going to need more info to try and help you figure out what the issue actually was. Sniff of the dhcp traffic would tell you exactly what was happening. Open it in wireshark.



  • @johnpoz

    I’ll try and get more data, for you.

    What do mean 50% over the server?

    Release and renew both failed until I did a “release *” (W10Pro, and W7Ultimate)

    Thanks, for the help.

    Mike


  • LAYER 8 Global Moderator

    Lets say the lease is for a length of 1 day (24hours) if a client asks for a renew say 2 hours into that lease - then the dhcpd will tell the client too bad your lease is still good.

    Let me see if I can find an example in my log of that.

    example:
    Sep 13 00:25:18 dhcpd DHCPREQUEST for 192.168.4.210 from 0c:51:01:8c:19:ae (Johns-Air2) via igb2.4
    Sep 13 00:25:18 dhcpd reuse_lease: lease age 975 (secs) under 25% threshold, reply with unaltered, existing lease for 192.168.4.210



  • @johnpoz

    That is not the response I’m getting. Also, the second entry does not respond a “reuse lease” response.

    BTW - The stale IP is out of the DHCP range.

    I’ll get more data and get back to you.


  • LAYER 8 Global Moderator

    So if your client is trying to renew an IP that is no longer in scope, it should give up and send a discover..

    So your saying client has say 192.168.1.100 from your original pool of .50 to .200, you then change your pool to .150-200 and wonder why the client just doesn't get new IP starting with .150 when you do a ipconfig /renew?

    Did you flush the old lease? Just because you change the pool size doesn't remove old leases that are no longer in scope.



  • @johnpoz

    Very close. The previous IP 192.168.26.51 and previous pool was .50 to .99, the new pool was .150 to .199

    Would I flush it on the dhcp server or client?


  • LAYER 8 Netgate

    What is the DHCP server logging?


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