0

I'm running the latest version of Pop! Os.

I have a laptop connected to my main computer via an ethernet cable.

The laptop IP is 169.254.83.40 and my main computer IP is 169.254.83.50 on the connected interface. My wifi interface is 192.168.0.20 on the main computer.

When I am connected to wifi and I attempt to ping my laptop from my main computer I get the following.

    PING 169.254.83.40 (169.254.83.40) 56(84) bytes of data.
    From 192.168.0.20 icmp_seq=1 Destination Host Unreachable
    From 192.168.0.20 icmp_seq=2 Destination Host Unreachable
    From 192.168.0.20 icmp_seq=3 Destination Host Unreachable

When disconnected from wifi I can ping successfully. Below is my output from ifconfig.

    enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 192.168.0.20  netmask 255.255.255.0  broadcast 192.168.0.255
    ether e8:4e:06:7d:d7:8f  txqueuelen 1000  (Ethernet)
    RX packets 38305  bytes 36156135 (36.1 MB)
    RX errors 0  dropped 1  overruns 0  frame 0
    TX packets 26255  bytes 3680006 (3.6 MB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

    enp4s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 169.254.83.50  netmask 255.0.0.0  broadcast 169.255.255.255
    ether a8:a1:59:2b:6c:ee  txqueuelen 1000  (Ethernet)
    RX packets 1294  bytes 87685 (87.6 KB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 1818  bytes 121833 (121.8 KB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

    lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
    inet 127.0.0.1  netmask 255.0.0.0
    inet6 ::1  prefixlen 128  scopeid 0x10<host>
    loop  txqueuelen 1000  (Local Loopback)
    RX packets 12029  bytes 1257930 (1.2 MB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 12029  bytes 1257930 (1.2 MB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

netstat -nr
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         192.168.0.1     0.0.0.0         UG        0 0          0 enp3s0
0.0.0.0         169.254.83.50   0.0.0.0         UG        0 0          0 enp4s0
169.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 enp4s0
169.0.0.0       169.254.83.50   255.0.0.0       UG        0 0          0 enp4s0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 enp3s0
192.168.0.0     0.0.0.0         255.255.255.0   U         0 0          0 enp3s0
1
  • The interfaces with 169.254.x.y addresses haven't managed to get IP addresses from whatever is supposed to be issuing them Aug 30, 2021 at 20:21

1 Answer 1

1

The reason that you are seeing this is that the wifi connection added a route that was more specific than the one on your wired connection (I've notated the important stuff with asterisks):

Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         192.168.0.1     0.0.0.0         UG        0 0          0 enp3s0
0.0.0.0         169.254.83.50   0.0.0.0         UG        0 0          0 enp4s0
**169.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 enp4s0
169.0.0.0       169.254.83.50   255.0.0.0       UG        0 0          0 enp4s0
**169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 enp3s0
192.168.0.0     0.0.0.0         255.255.255.0   U         0 0          0 enp3s0

(enp4s0 is wired, enp3s0 is wireless)

The route that your wired network takes to get to 169.254.83.40 is 169.0.0.0/255.0.0.0 (aka /8), while the wifi network adds a route that is 169.254.0.0/255.255.0.0 (aka /16). The /16 is considered more specific because it refers to a smaller network, so it takes priority over the wired network.

As to how to fix the problem, I'd check the wireless network configuration or DHCP server to see why the additional routes are being pushed. In the meantime, you can manually remove the erroneous route with

ip route del 192.254.0.0/16 dev enp3s0

but that isn't a real fix, just a band-aid.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .