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

    Possible to port mirror or duplicate packets?

    Scheduled Pinned Locked Moved General pfSense Questions
    5 Posts 3 Posters 2.6k 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.
    • S Offline
      sofakng
      last edited by

      I have a strange question…

      Is it possible to "port mirror" or duplicate packets using pfSense?

      For example, whenever packets match a certain filter (i.e. TCP ADDR 192.168.0.25, port 80), duplicate that packet to another IP address, etc.

      Does that make sense?  It's sorta like a poor-man's port filtering.

      1 Reply Last reply Reply Quote 0
      • L Offline
        loupalladino
        last edited by

        What are you trying to do with the duplicated packet?

        I do this at the switch level - Cisco calls it "port monitoring".  I had ntop installed on pfsense and connected to the mirrored port on the switch.

        -Lou

        1 Reply Last reply Reply Quote 0
        • S Offline
          sofakng
          last edited by

          Yeah, I'm having a problem with my switch.  It's a Dell PowerConnect 2824 managed switch, and it supports port mirroring, but on my "low end" model it doesn't allow mirroring if VLANs are enabled which I use.

          What I'm trying to do is send any SIP INVITE packets to a sniffer application to read the caller id and broadcast it on my network (for call notifications, etc).

          I'd rather not setup a full SIP proxy or anything… The SIP sniffer I have already reads caller id so I just need to get those packets to my sniffer and my VOIP adapter (of course).

          1 Reply Last reply Reply Quote 0
          • jimpJ Offline
            jimp Rebel Alliance Developer Netgate
            last edited by

            Not sure if you can do it with just one port, but if you bridge two ports together you can add a third port as a "span" port and it receives copies of every frame transmitted across the bridge.

            Remember: Upvote with the 👍 button for any user/post you find to be helpful, informative, or deserving of recognition!

            Need help fast? Netgate Global Support!

            Do not Chat/PM for help!

            1 Reply Last reply Reply Quote 0
            • L Offline
              loupalladino
              last edited by

              I'm still somewhat of a pfsense newbie, but since there is no obvious "rule" (would be nice if there was PASS, BLOCK, REJECT, MIRROR :) ), not sure if can do this.  You could "rig" it up in a pinch using a hub…... I know, far less than ideal but if it limps you along in the meantime while you figure something else out, it's worth contemplating at the least.

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