In pfsense arp entries are not populating in arp table for some host machines



  • In pfsense arp entries are not populating in "arp table" for some host machines. due to which internet is not working on the host, which have DHCP assigned an IP address.

    when I give a static IP address to the host, the internet is working and arp entry of that host is also getting populated in arp table.



  • This stuff should work automatically without any intervention.  I got both DHCP and static and never a problem. U got something going on in there that's unknown to us. Did this EVER worked?  Problem since day#1?

    When the registration time runs out, the MAC would indeed disappear from the ARP table but as soon as traffic is initiated again on that IP, the ARP registration should again establish, immediately, behind your back, wo any intervention. Ur not working, u did something.


  • LAYER 8 Global Moderator

    If your getting dhcp from pfsense, are you saying you can not ping pfsense?  And the client can not arp for pfsense IP.

    What is pfsense IP on this network?  What is your dhcp setting does the dhcp client get?

    if you saying it works with static, but doesn't work with dhcp but client gets dhcp then points to different dhcp server pointing to different gateway or something.

    But without more info not possible to help you figure out what is wrong.  Post up some details, arp table from client when working.  Arp table from client and IP info when not working, etc.



  • @ravirk:

    In pfsense arp entries are not populating in "arp table" for some host machines. due to which internet is not working on the host, which have DHCP assigned an IP address.

    when I give a static IP address to the host, the internet is working and arp entry of that host is also getting populated in arp table.

    ????

    Arp entries are normally found in the arp tables of devices that have had communications with.  That is if computer A contacts B, then A will be in B's arp cache and B will be in A's cache.  Also, arp entries expire after a while, so there's a good chance there will not be an arp cache entry anywhere for a device.  Try pinging another computer and see if there is an arp entry in that device.  It should make no difference whether you use DHCP or static addresses, so long as it's a valid address for the network.



  • Thanks for all your replies.

    let me explain my scenario, we have pfsense acting has a firewall/gateway and DHCP server.

    subnet:-192.x.x.0

    Subnet mask:-255.255.255.0

    DHCP address range is x.x.x.10 to x.x.x.200

    From x.x.x.201 to x.x.x.254 i am using them as static IPs for some other devices/hosts

    Gateway address x.x.x.1

    ISP DNS 202.56.230.2/7

    –--------------------------------------------------------------------
    Firstly when a host is connected to the network it got IP x.x.x.176 assigned but no internet and unable to ping gateway and 8.8.8.8

    Host IP:-x.x.x.176
    gateway IP:-x.x.x.1

    The one more thing in " StatusDHCP Leases" is showed status "offline" and lease type "active" and

    in  "DiagnosticsARP Table" there was not an entry for this IP and MAC address.


    Next when I assigned a static IP x.x.x.222 to same host, now it was able to ping gateway & global DNS and internet was working.

    Now " StatusDHCP Leases" is showed status "online" and lease type "static" and

    In "DiagnosticsARP Table" there were entries of this IP and MAC address mappings.


    So i have captured packets in pfsense in 2 phases  first on DHCP assigned IP and next on staticly assigned IP attached the wireshark screen shots, one thing i observed complete  DHCP-DORA process was not happening on dynamic DHCP  IP.

    This was not happenign from begining and it is there for 20 to 30 machines only not for all, it was there for some new laptops also.






  • @ravirk:

    subnet:-192.x.x.0
    Subnet mask:-255.255.255.0
    DHCP address range is x.x.x.10 to x.x.x.200
    From x.x.x.201 to x.x.x.254 i am using them as static IPs for some other devices/hosts
    Gateway address x.x.x.1
    ISP DNS 202.56.230.2/7
    –--------------------------------------------------------------------
    Firstly when a host is connected to the network it got IP x.x.x.176 assigned but no internet and unable to ping gateway and 8.8.8.8

    x.x.x make answering impossible or at least not accurate

    Know that a billion people use exactly the same  non-routable 192.x.x.x - so no need to hide them.
    We all have (on planet earth) these same 192.168.1.0/24
    Addresses are important, they work closely with ARP messages.

    You have a pretty impossible problem, I advise you to play the game without hiding your cards ;)


  • LAYER 8 Global Moderator

    ^ exactly!!!  The only thing hiding rfc1918 points to is someone that just doesn't get how any of this works..


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