Ping with DUP!



  • Hi,
    I am trying to configure an IP camera and had it connected with a wire to login and configure WiFi access. During this process I noticed few weird things namely:

    1. The ping out to wireless IP contains DUP! in the output
    PING 192.168.20.93 (192.168.20.93) 56(84) bytes of data.
    64 bytes from 192.168.20.93: icmp_seq=33 ttl=63 time=1.88 ms
    64 bytes from 192.168.20.93: icmp_seq=33 ttl=63 time=1.92 ms (DUP!)
    64 bytes from 192.168.20.93: icmp_seq=34 ttl=63 time=10.7 ms
    64 bytes from 192.168.20.93: icmp_seq=34 ttl=63 time=10.7 ms (DUP!)
    64 bytes from 192.168.20.93: icmp_seq=35 ttl=63 time=1.86 ms
    64 bytes from 192.168.20.93: icmp_seq=35 ttl=63 time=1.89 ms (DUP!)
    
    
    1. The wireless interface works (trying to login using Wireless IP) as long as the Ethernet wire is connected which has a different IP address. Ping to the wireless IP (with DUP! in the output) only works when the Ethernet cable is connected to camera.

    So seems like that packet for wireless IP are getting routed through the wired interface which seems bizarre to me. So just curious if this is normal behavior when there are multiple network interfaces attached to the same device?

    Thanks.


  • Netgate Administrator

    No that's never normal.

    Run a packet capture for that and check the MAC addresses. Check the system log for ARP movement mesages, the different IP should not cause that though. The variation in ping times there makes it look like maybe alternate pings are going via wifi and Ethernet.

    Steve



  • @stephenw10 thanks for the pointers!

    I messed up my camera to a point where I had to factory reset, the problem disappeared after reset and not getting DUP! pings any more. But I will watch out if that happens again and share the results of packet capture.


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