[Solved] Why do I have two WAN links on my ARP table?



  • Hey guys, I'm studying some networking stuff and I just happened to go into my dashboard and check out my ARP table and then I noticed that I have two WAN connections. The IP addresses have the same prefixes (I just blocked them out visually for privacy) and one ends in x.x.110.1 and the other x.x.111.21

    At first, I was just assuming that maybe one of them is for the WAN device on my pfSense box and the other is my modem.. but then I looked at the MAC address on my modem and it doesn't match either MAC in the ARP table.

    The way I have my system configured is this pretty simple: I have my ISP modem connecting to the WAN interface on my pfSense box and then my LAN interface connects to my unmanaged switch which I have wired computers and one WRT54GL (wireless router) connected. The WRT54GL's WAN is assigned a static IP by DHCP server on pfSense.

    I checked my public IP with google and it's the x.128.111.21 one (which I assumed) and the other WAN IP which ends in '1', tells me that it's probably my modem (however the MAC's don't match). I don't quite understand what's going on.

    If anyone can help me understand, I would appreciate it.

    Picture included



  • If you are going to obscure the mac addresses, block out the end of it. The first three parts would identify the manufacturer of the equipment.
    I'd guess the two macs are your firewall and the gateway. If the modem is a bridge, then it's not your gateway.



  • @dotdash:

    If you are going to obscure the mac addresses, block out the end of it. The first three parts would identify the manufacturer of the equipment.

    Yeah I know and I left only the last two bytes so someone could see the difference.

    I'd guess the two macs are your firewall and the gateway. If the modem is a bridge, then it's not your gateway.

    Yeah the x.x.111.21 is my WAN entry but I don't know what the other one is.. unless it's the actual interface all the way at my ISP.


  • Rebel Alliance Developer Netgate

    That's your gateway. If it wasn't in your ARP table, you wouldn't be able to send out any packets through it :-)
    Unless it's DSL or a similar PPP-based line, but in that case your own MAC wouldn't show there, either.



  • @jimp:

    That's your gateway. If it wasn't in your ARP table, you wouldn't be able to send out any packets through it :-)
    Unless it's DSL or a similar PPP-based line, but in that case your own MAC wouldn't show there, either.

    Okay yeah it makes sense to me now. I am just so rusty since I don't do this every day like I need to. My ARP table holds entries for not just my local private network, but also stuff on the external network. I have the entry for my public address which is associated with my WAN card and then I have the entry for it's gateway which is the path out to the greater network/internet.