How can I find out, why pfSense is blocking an internal IP?



  • Hi, I‘m having a strange problem: On a subnet, there is one specific IP that pfSense is blocking: The subnet is my wifi. Any device tested an assigned this IP to via dhcp or manually can ping the AP and the switch in between, but not pfSense (2.4.4-2).

    I tested opening the firewall (a pass-all rule at the top) for that VLAN on pfSense (even though all blocking rules have logging enables and there is no trace in the logs). I also tried

    cat /conf/config.xml | grep <IP>
    

    but that also showed no trace of anything related to this IP in pfSense‘s.

    Anything else I could check to see if there is anything in pfSense‘s config about this IP?



  • Post a screenshot of your firewall rules for the interface with the problem.


  • LAYER 8 Global Moderator

    So can we have some actual IPs to work with here..

    So your saying for example

    Pfsense interface IP 192.168.1.1
    client on 192.168.1/24 say .14 or .231 can ping .1
    But this IP 192.168.1.52 can not ping .1, no matter what device gets or uses this .52 address?

    Is that what your saying??



  • @johnpoz: Yes. that’s what I‘m trying to say.

    pfSense interface IP is 192.168.5.1 with clients on 192.168.5.0/24. 192.168.5.27 can’t ping pfSense or anything behind pfSense, independent of which device has been assigned this IP. With other IPs (e.g. 192.168.5.28), the same devices can ping pfSense and IPs behind pfSense.

    I haven’t experienced this issue with any other IP yet. Trying to find out what I may have misconfigured.

    Firewall rules screenshot is a bit difficult from mobile devices, but maybe this is sufficient already:

    screen shot


  • LAYER 8 Global Moderator

    So you double check same mask on both pfsense and client.

    What are you firewall rules? Any floating rules?

    So on your client, when you try and ping pfsense on 192.168.5.1, you see his mac in your arp table after you try and ping... And this mac address is correct, ie matches up with pfsense mac address.



  • @johnpoz : The arp table was an excellent hint. After playing around with it and making sure it is ok, everything is working - with all devices.

    Thanks!


  • LAYER 8 Global Moderator

    So what was wrong in the arp table? Was there a static arp set on pfsense?



  • There was an entry for the IP, yes. Don't know where it came from, and after deletion, I couldn't make it appear again - only temporary ones, which kept changing as I changed devices with that IP.

    In any case, the ARP table was the correct pointer, thanks again!


  • LAYER 8 Global Moderator

    NP - glad you got it sorted..


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