Netgate Discussion Forum
    • Categories
    • Recent
    • Tags
    • Popular
    • Users
    • Search
    • Register
    • Login

    ARP Tables...Most Static Addresses are No Longer Permanent

    Scheduled Pinned Locked Moved General pfSense Questions
    26 Posts 5 Posters 3.3k Views
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • ARAMP1A
      ARAMP1 @johnpoz
      last edited by

      Ah...Yeah, just confirmed that's the case. Rebooted and all the permanent entries are gone (except for the VLAN interfaces themselves).

      Well, thanks again @johnpoz for your help. 🄃

      johnpozJ 1 Reply Last reply Reply Quote 0
      • johnpozJ
        johnpoz LAYER 8 Global Moderator @ARAMP1
        last edited by johnpoz

        @ARAMP1 you might want to just chime in on that redmine, that you too are seeing it.. Or I can make a comment if you want, and link to this thread.

        I made a comment and linked to this thread.

        An intelligent man is sometimes forced to be drunk to spend time with his fools
        If you get confused: Listen to the Music Play
        Please don't Chat/PM me for help, unless mod related
        SG-4860 24.11 | Lab VMs 2.8, 24.11

        1 Reply Last reply Reply Quote 2
        • Z
          zkhcohen
          last edited by

          I can also validate that Regression #14374 is present on my 3.7.0 installation.

          I noticed that simply opening and saving each DHCP entry with static ARP assigned (without making any changes) will resolve the issue for that specific entry. Rebooting the DHCP service has no impact.

          Another interesting note - when I create an XML backup of my pfSense config and inspect it, all the proper static ARP entries are present. In other words, the configuration is present, it's just not being initialized properly on reboot. Note that I haven't had a chance to test the secondary symptom -- the eventual erasure of static ARP entries for inactive devices.

          Setting up an hourly cron job / shellcmd which sets "arp -s <ip> <mac>" for each entry is the best solution until a patch has been issued.

          Z 1 Reply Last reply Reply Quote 0
          • Z
            zkhcohen @zkhcohen
            last edited by

            Here's a script which leverages python3.11 to search for and set static arp entries:

            Step 1. Create a shell script called "arp.sh" in the /usr/local/etc/rc.d/ directory:

            #!/bin/sh
            
            python3.11 - <<EOF
            import xml.etree.ElementTree as ET
            import subprocess
            
            # Load the XML file
            tree = ET.parse("/conf/config.xml")
            root = tree.getroot()
            
            # Extract the IP and MAC addresses using list comprehension
            results = [{'mac': staticmap.find("mac").text, 'ip': staticmap.find("ipaddr").text}
                       for staticmap in root.iter("staticmap")
                       if staticmap.find("arp_table_static_entry") is not None]
            
            # Execute the arp commands
            for result in results:
                command = f"arp -s \"{result['ip']}\" \"{result['mac']}\""
            
                print("Command:", command)
            
                completed_process = subprocess.run(command, shell=True, executable="/bin/sh", capture_output=True, text=True)
            
                if completed_process.returncode == 0:
                    print("Command executed successfully.")
                    print("Output:", completed_process.stdout)
                else:
                    print("Command execution failed.")
                    print("Error:", completed_process.stderr)
            EOF
            

            Step 2. Run: chmod +x /usr/local/etc/rc.d/arp.sh
            Step 3. In the pfSense UI, navigate to Services > Cron and create the following job:

            0 	* 	* 	* 	* 	root 	/bin/sh /usr/local/etc/rc.d/arp.sh
            

            Step 4. To execute the command manually, run /bin/sh /usr/local/etc/rc.d/arp.sh. Upon checking the pfSense UI Diagnostics > ARP Table, you should see that all of the entries are now "Permanent".

            johnpozJ 1 Reply Last reply Reply Quote 0
            • johnpozJ
              johnpoz LAYER 8 Global Moderator @zkhcohen
              last edited by

              @zkhcohen so your script looks to what is in the arp table and makes them all static - ie perm? That would be a horrible idea

              An intelligent man is sometimes forced to be drunk to spend time with his fools
              If you get confused: Listen to the Music Play
              Please don't Chat/PM me for help, unless mod related
              SG-4860 24.11 | Lab VMs 2.8, 24.11

              Z 2 Replies Last reply Reply Quote 0
              • Z
                zkhcohen @johnpoz
                last edited by

                @johnpoz No. It looks for a pre-existing permanent static arp mapping in the DHCP config and then reapplies it via the CLI.

                1 Reply Last reply Reply Quote 0
                • Z
                  zkhcohen @johnpoz
                  last edited by

                  @johnpoz

                  A patch was just issued (extremely quickly, I might add), and I can confirm that it fixes the issue in my environment:

                  https://redmine.pfsense.org/projects/pfsense/repository/2/revisions/5082edf92795fe8266be49905fe4f07eb682449d

                  1 Reply Last reply Reply Quote 1
                  • ARAMP1A
                    ARAMP1
                    last edited by

                    The patch does not appear to work on 2.7.0.

                    johnpozJ 1 Reply Last reply Reply Quote 0
                    • johnpozJ
                      johnpoz LAYER 8 Global Moderator @ARAMP1
                      last edited by

                      @ARAMP1 I just tested this on my 2.7 vm and seems to be working..

                      So I created a static arp and it was there.

                      staticarp.jpg

                      I then rebooted and it was gone.

                      missing.jpg

                      I then applied the patch, and rebooted again and now its there.

                      fixed.jpg

                      An intelligent man is sometimes forced to be drunk to spend time with his fools
                      If you get confused: Listen to the Music Play
                      Please don't Chat/PM me for help, unless mod related
                      SG-4860 24.11 | Lab VMs 2.8, 24.11

                      1 Reply Last reply Reply Quote 0
                      • ARAMP1A
                        ARAMP1
                        last edited by

                        Must have been user error....I got it working. After a couple restarts and wondering what I did wrong, I reinstalled the patch and everything is working.

                        Appreciate the help, gents.

                        3 1 Reply Last reply Reply Quote 1
                        • 3
                          32G3LiQxu8 @ARAMP1
                          last edited by

                          I’m seeing this behavior in 23.09. ARP table shows dynamic (expires in <time>) ARP entry instead of static (permanent).

                          If I uncheck, ā€œCreate an ARP Table Static Entry for this MAC & IP Address pairā€ and then save.

                          Then recheck ā€œCreate an ARP Table Static Entry for this MAC & IP Address pairā€ and then save.

                          Then go back to ARP table, almost all the dynamic entries are flipped to static (permanent)

                          Anyone else seeing this?

                          johnpozJ 1 Reply Last reply Reply Quote 0
                          • johnpozJ
                            johnpoz LAYER 8 Global Moderator @32G3LiQxu8
                            last edited by johnpoz

                            @32G3LiQxu8 there seems to be an issue with when clients update their lease - there is this thread.

                            https://forum.netgate.com/topic/184155/static-arp-in-dhcp-overwritten

                            And this redmine

                            https://redmine.pfsense.org/issues/14970

                            So yeah if it has flipped to dynamic, a resave of the dhcp page where you set it as static will turn it back to perm, but it seems when client updates its lease again it will go back to dynamic.. See the thread linked to above, where you can duplicate it doing it by just having your client release and renew its lease.

                            From the redmine it seems to be correct in the upcoming 24.03 and 2.8 CE releases

                            "This is not reproducible on the latest builds of 2.8.0 and 24.03"

                            An intelligent man is sometimes forced to be drunk to spend time with his fools
                            If you get confused: Listen to the Music Play
                            Please don't Chat/PM me for help, unless mod related
                            SG-4860 24.11 | Lab VMs 2.8, 24.11

                            3 1 Reply Last reply Reply Quote 0
                            • 3
                              32G3LiQxu8 @johnpoz
                              last edited by

                              @johnpoz Thank you for the information. I will wait for a fix.

                              1 Reply Last reply Reply Quote 0
                              • First post
                                Last post
                              Copyright 2025 Rubicon Communications LLC (Netgate). All rights reserved.