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Editorial Team
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Asked: 2026-05-30T09:18:41+00:00

How do you programmatically determine under Linux if your current active ethernet interface is

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How do you programmatically determine under Linux if your current active ethernet interface is a wireless device?

For example, my machine has a wired and wireless interface, and the output of my ifconfig is:

eth0      Link encap:Ethernet  HWaddr 64:b9:e9:cd:4f:b3  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:7700676 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3412854 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:3131639132 (3.1 GB)  TX bytes:16826666276 (16.8 GB)
          Interrupt:27 Base address:0x4000 

eth2      Link encap:Ethernet  HWaddr 01:16:4b:1b:90:c9  
          inet addr:192.168.1.152  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fa81::216:baff:de1b:91cc/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2307478 errors:15 dropped:0 overruns:0 frame:18469924
          TX packets:1924909 errors:527 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2475924284 (2.4 GB)  TX bytes:996430577 (996.4 MB)
          Interrupt:23

Is there anything there that identifies one as wireless?

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1 Answer

  1. Editorial Team

    While it may be common for all network traffic to go over a single interface—especially in a single adapter system—it is not true in the general case. For example, my laptop commonly alternates routing over wi-fi and its 100baseT cable.

    Inspect the output of ip route for a wlan entry. That, at least, indicates whether there could be wireless traffic. The default route is probably the best indication.

    Hardwired system:

    [wally@lenovotower ~]$ ip route
default via 192.168.0.1 dev eth0  proto static 
192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.103  metric 1 
192.168.122.0/24 dev virbr0  proto kernel  scope link  src 192.168.122.1

    Wi-fi system:

    [wally@lenovafedora ~]$ ip route
192.168.0.0/24 dev wlan0  proto kernel  scope link  src 192.168.0.105  metric 2 
192.168.122.0/24 dev virbr0  proto kernel  scope link  src 192.168.122.1 
default via 192.168.0.1 dev wlan0  proto static
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