I have a Debian system working as a wireless router with eth0 and wlan0. Now I added an additional network manually on eth1 with ifconfig:

alix:~# ifconfig eth1 netmask
alix:~# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface         UG        0 0          0 eth0   U         0 0          0 eth1   U         0 0          0 eth0   U         0 0          0 wlan0
alix:~# ping
PING ( 56(84) bytes of data.
64 bytes from icmp_req=1 ttl=64 time=0.537 ms
64 bytes from icmp_req=2 ttl=64 time=0.199 ms
64 bytes from icmp_req=3 ttl=64 time=0.188 ms
--- ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2005ms
rtt min/avg/max/mdev = 0.188/0.308/0.537/0.161 ms

Everything works fine as you can see.

Now I would like to make the configuration permanent. Therefor I added the following section to /etc/network/interfaces:

alix:~# sed -n '/iface eth1/,/^$/p' /etc/network/interfaces
iface eth1 inet static

But when I try to start the network I get the following error:

alix:~# ifconfig eth1 down
alix:~# ifup -v eth1
Configuring interface eth1=eth1 (inet)
run-parts --verbose /etc/network/if-pre-up.d
run-parts: executing /etc/network/if-pre-up.d/hostapd
ip addr add broadcast     dev eth1 label eth1
RTNETLINK answers: File exists
Failed to bring up eth1.

When I run the ip command manually I get the same error:

alix:~# ip addr add broadcast     dev eth1 label eth1
RTNETLINK answers: File exists

What is wrong with the command? And how can I tell Debian to do the right thing?


3 Answers 3


I got it that I had to flush the device before bringing it up:

# ip addr flush dev eth1

Clearing manually set interface configuration information like this is mentioned in the Ubuntu Server Guide.

  • I still receive a (slightly different) error RTNETLINK answers: No such process Failed to bring up eth1 BUT my Eth1 is correctly assigned now AND is UP/UP. Commented Sep 10, 2015 at 14:11
  • yeah, same problem here: RTNETLINK answers: No such process Failed to bring up eth1
    – Drew
    Commented Feb 21, 2017 at 5:50
  • 14
    Even if your answers solves the problem. It would be great if you could tell what it actually does. What is this RTNETLINK file that exists? Commented May 17, 2017 at 7:19
  • 1
    @realtebo @humanityANDpeace Inspect the kernel manual about netlink and rtnetlink. But I doubt you really want to know. This is an error message the ip tool gets from the kernel. And instead of translating the message into something useful for end users, ip passes it just through. But if you really want to know the internals, use the Ask Question instead of the Add Comment button.
    – ceving
    Commented Aug 14, 2018 at 8:43
  • 3
    One caveat is that this clears all scopes, which is not always what you want. (I found that out the hard way)
    – Semimono
    Commented Oct 5, 2018 at 19:17

Using ip addr flush will work, but it will also clear any and all addresses set on that interface - possibly including the one that you are using, if you're logged in to a remote machine. This may lock you out of your device.

RNETLINK answers: File exists happens when you're trying to add a rule that conflicts with an existing rule. I would guess that OP was encountering this because they had already set the address with ifconfig. This error can usually be resolved by converting the add command to a similarly structured change or replace command.

It's much safer to use ip addr change or ip addr replace instead.

  • 1
    This is no option for someone using just ifup and ifdown, because the command is hard wired in those scripts.
    – ceving
    Commented Jul 31, 2020 at 14:14
  • @alerone using "sudo ip addr change" will throw me this output. "Not enough information: "dev" argument is required." I/We need more info to use ur idea. It would be nice.
    – Pranav
    Commented Oct 28, 2020 at 6:17
  • This answer explained my issue, I had conflicting routes in my /etc/network/interfaces
    – kasi
    Commented Apr 29, 2021 at 12:18
  • @Pranav You must complete the command with the required parameters. For example sudo ip addr change dev eth0. In your case the missing parameter seems to be the name of network interface (the device). Also, you can read the online help with this command ip addr help.
    – Daishi
    Commented Oct 13, 2022 at 21:59

I had a similar problem that by the time I had played the 10,000 moneys scene was exactly this, and I had been trying to add the missing stuff to /e/n/i.d/etho

But studying the man page for interfaces, I noted that ALL of the set of examples had only 2 lines of real data, the ipv4 address/24, and a gateway line specifying the address of my router. So I stripped my eth0 file down to that, and rebooted, and worked perfectly.

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