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    Modem O&M behind NAT reachable, but why??

    Scheduled Pinned Locked Moved NAT
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    • S
      Stefanix
      last edited by

      I installed recently the cable modem Arris CM3500B and pfSense CE. I wondered how I could reach the modem's O&M interface on the WAN side from the LAN through NAT. I played around, entered the modem's IP (192.168.100.1) and surprisingly it works without any special configuration! My LAN is on 192.168.188.0/24. How does a NAT setup handle destination IPs of private networks? 192.168.100.0/24 should be unknown to pfSense. The WAN side gets the public WAN IP form the ISP per DHCP as soon as the modem has synced. I am surprised that I can reach the modem's private IP over the pfSense WAN interface and would like to understand why this works. Private IP destinations shouldn't traverse outgoing NAT, right? Any idea?

      Bob.DigB 1 Reply Last reply Reply Quote 0
      • Bob.DigB
        Bob.Dig LAYER 8 @Stefanix
        last edited by Bob.Dig

        @Stefanix said in Modem O&M behind NAT reachable, but why??:

        Private IP destinations shouldn't traverse outgoing NAT, right?

        Why do you think that.

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