I am stuck with some strange behavior comming from my linux system. I have two ethernet interfaces (eth0 and eth1). When trying to set them up for the first time (for example with ifup eth1, or ifconfig eth1 up), I get the following :

IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready

However, networking seems working fine (ping or ssh works fine). Sometimes after a few seconds, I get:

IPv6: ADDRCONF(NETDEV_UP): eth0: link is ready

If I try another ifup, I get no message error.

It might seems it is not a problem, but I am afraid that it is hiding a configuration problem either in the kernel or in the networking side.

Steps I did to solve the prblem or get a better understanding :

Step#1 As I had no interfaces configuration file, I added one in /etc/networking:

# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static

auto eth1
iface eth1 inet static

That didn't change anything.

Step#2 I thought it might comes from busybox (I have seen some different behavior between a linux tool in busybox and the 'real one'. So, I compiled the ifupdown package for my target. That didn't help.

Step#3 I went to the kernel configuration, and the IPv6 support was compiled as module so I made it mandatory, so it is loaded at boot. That didn't help.

From, what I have seen on the web, others had the same problem but didn't find a solution. They usually added a script at boot that tries a ifup so the user doesn't see an error messages after that. I do not find that satisfactory, as I stated previously: I am afraid that there is a bigger problem.

Any ideas where the problem might come from?

  • Does the network you're connecting to have IPv6 in use, and if it has, are there IPv6 router advertisements detectable in the network (i.e. do other systems in the same network detect an IPv6 gateway in the network)? Which Linux distribution are you using (apparently Debian/Ubuntu or some derivative)? Is NetworkManager service installed and running? – telcoM Sep 19 '18 at 6:31

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