I often use the ping -I option to test if an interface forwards packets correctly.

A Raspberry Pi 3 has an interface named eth1. It is a USB to female ethernet connector. I manually configured this interface with the ip address

When I perform ping -I eth1 example.com I receive a "Destination host not reachable" message. However when I issue ping -I example.com, the ping command replies correct.

I am curious why the results differ. Can anybody explain?

  • Curious, do you have outgoing rules defined in iptables/ufw. This could cause this behavior.
    – Sabre
    Oct 31 at 16:42
  • To be sure of anything you should provide your current network state with these commands: ip -br link; ip -4 -br address; ip -4 route; ip -4 rule as well as (for a few hints) ip -4 neigh after having tried both kinds of ping. Of course the effect of both kinds of ping is different but without seeing the configuration first, it's not worth trying to explain an hypothetical cause.
    – A.B
    Oct 31 at 18:28


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