Is it possible to set an IP address to an interface?

[Maria Matejka]

Hello Robért,

BIRD basically doesn't set IP addresses to interfaces. This is a design 
choice of the current team. Please use external tooling for this.

To elaborate a bit more, because we get these kinds of questions 
repeatedly → Implementing of this feature would open a huge can of 
worms, or a very large rabbithole (choose your best option) of features:

  * setting tunnel endpoint IPs
  * implementing DHCP client
  * implementing VRRP
  * creating and destroying tunnel interfaces
  * setting interfaces up and down
  * setting up wireguard links
  * …

Yes, we could become another NetworkManager … and to be honest, I 
sometimes wish to go this way when seeing how badly NM is handling some 
specific corner cases. Anyway, it's a lot of work. A LOT of work. An 
absurdly huge pile of hard work to get there.

Of course, if there is demand for this, and we are closely monitoring 
what the users think and wish, we may rethink this design choice.

Thank you for your understanding
Maria

On 2023-10-24 17:29, Robért Guhr wrote:
> Hi,
>
> is it possible to set an ipv4 address (e.g. "10.186.100.11/32 
> <http://10.186.100.11/32>" ) via bird on a dummy interface called 
> "anycast"?
> I mean via the bird config not via bgp/ospf pushes.
>
> Background:
>
>     I have setup four DNS server in two sites. All these DNS servers
>     announces 10.186.100.11/32 <http://10.186.100.11/32> (and
>     10.186.100.12/32 <http://10.186.100.12/32>) up to the routers to
>     create an anycast environment.
>     Currently 10.186.100.11/32 <http://10.186.100.11/32> (and
>     10.186.100.12/32 <http://10.186.100.12/32>) are set fixed on the
>     dummy interface. Bird just imports these IP addresses.
>
>     We would like to use 10.186.100.11/32 <http://10.186.100.11/32>
>     and 10.186.100.12/32 <http://10.186.100.12/32> as resolver in
>     /etc/resolv.conf
>     But if we stop the local DNS server then the dns resolution is no
>     longer possible because the addresses are hardcoded on the local
>     interface and the other three dns server will not be used.
>
>
>     Idee was to set the ip addreses via bird so that when we stop Bird
>     and the local DNS server, we automatically forward the DNS
>     requests to the other three servers.
>
>
> I was hoping the direct protocol converts a route also to an ip 
> address but this seems not to be the case.
> With the kernel protocol I can export the route to the kernel routing 
> table but that is not was I was want.
>
> pns-b2-ns02 ~ # cat /etc/bird.conf
> # Ansible managed
>
> router id 10.186.244.12;
>
> protocol device {
>   scan time 10;
> }
>
> protocol direct {
>   ipv4 {
>     import none;
>     export all;
>   };
>   interface "anycast";
> }
>
> protocol static {
>   ipv4 {
>     import all;
>     export all;
>   };
>   route 10.186.100.11/32 <http://10.186.100.11/32> via "anycast";
> }
>
> protocol kernel {
>   ipv4 {
>     import none;
>     export all;
>   };
> }
>
>
>
>
>
> pns-b2-ns02 ~ # birdc show route; echo; ip a show dev anycast; echo; 
> ip r | grep 10.186.100
>
> BIRD 2.13.1 ready.
> Table master4:
> 10.186.100.11/32 <http://10.186.100.11/32>     unicast [static1 
> 17:22:18.282] * (200)
> dev anycast
>
> 4: anycast: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state 
> UNKNOWN group default qlen 1000
>     link/ether 8e:b5:2b:bf:0d:5e brd ff:ff:ff:ff:ff:ff
>     inet 10.186.100.9/32 <http://10.186.100.9/32> scope global 
> noprefixroute anycast          # <----- here should also be the 
> address 10.186.100.11/32 <http://10.186.100.11/32>
>        valid_lft forever preferred_lft forever
>
> 10.186.100.11 dev anycast proto bird scope link metric 32
>
>
>
> Regards,
> Robért

-- 
Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.
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