Bird is a commonly used BGP daemon. This page provides configuration and help to run Bird for dn42. Compared to quagga, bird supports multiple routing tables, which is useful, if you also plan to peer with other federated networks such as freifunk. In the following a working configuration for dn42 is shown. If you want to learn the practical details behind routing protocols in bird, see the following guide

Debian

The version in the Debian repositories might be quite old, therefore it makes sense to install a newer one directly from bird:

wget -O - http://bird.network.cz/debian/apt.key | apt-key add -
apt-get install lsb-release
echo "deb http://bird.network.cz/debian/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/bird.list
apt-get update
apt-get install bird

In case you are running Debian Jessie and this is not working for you, try replacing jessie with wheezy in the /etc/apt/sources.list.d/bird.list.

Example configuration

• Replace <AS> with your Autonomous System Number (only the digits)
• Replace <GATEWAY_IP> with your gateway ip (the internal dn42 ip address you use on the host, where dn42 is running)
• Replace <SUBNET> with your registered dn42 subnet, which you allocated on nixnodes
• Replace <PEER_IP> with the ip of your peer who is connected with you using your favorite vpn protocol (openvpn, ipsec, tinc, …)
• Replace <PEER_AS> the Autonomous System Number of your peer (only the digits)
• Replace <PEER_NAME> a self chosen name for your peer

IPv6

#/etc/bird/bird6.conf
protocol device {
  scan time 10;
}

# local configuration
######################

include "/etc/bird/local6.conf";

# filter helpers
#################

include "/etc/bird/filter6.conf";

# Kernel routing tables
########################


/*
    krt_prefsrc defines the source address for outgoing connections.
    On Linux, this causes the "src" attribute of a route to be set.
    
    Without this option outgoing connections would use the peering IP which
    would cause packet loss if some peering disconnects but the interface
    is still available. (The route would still exist and thus route through
    the TUN/TAP interface but the VPN daemon would simply drop the packet.)
*/
protocol kernel {
  scan time 20;
  device routes;
  import none;
  export filter {
    if source = RTS_STATIC then reject;
    krt_prefsrc = OWNIP;
    accept;
  };
}

# static routes
################

protocol static {
  route <SUBNET> reject;
  import all;
  export none;
}

template bgp dnpeers {
  local as OWNAS;
  path metric 1;
  import keep filtered;
  import filter {
    if is_valid_network() && !is_self_net() then {
      accept;
    }
    reject;
  };
  export filter {
    if is_valid_network() then {
      accept;
    }
    reject;
  };
  route limit 10000 action block;
}

include "/etc/bird/peers6/*";

# /etc/bird/local6.conf
# should be a unique identifier, use same id as for ipv4
router id <GATEWAY_IP>;

define OWNAS =  <AS>;
define OWNIP = <GATEWAY_IP>;

function is_self_net() {
  return net ~ [<SUBNET>+];
}

Generate the filter list from the monotone repository

$ cd net.dn42.registry
$ ruby utils/bgp-filter.rb --format bird < data/filter6.txt > /etc/bird/filter6.conf

or

$ curl -sk https://ca.dn42.us/reg/filter6.txt | \
    awk '/^[0-9]/ && $2 ~ /permit/ {printf "%s{%s,%s}\n", $3, $4, $5}' | \
    awk 'BEGIN {printf "function is_valid_network() {\n return net ~ [\n"} \
        NR > 1 {printf ",\n"} {printf "  %s", $1}
        END {printf "\n ];\n}\n"}' > /etc/bird/filter6.conf

example filter list:

function is_valid_network() {
  return net ~ [
    fc00::/8{48,64}, # ULA (undefined)
    fd00::/8{48,64}, # ULA (defined)
    2001:67c:20c1::/48{48,48}, # E-UTP IPv6
    2001:bf7::/32{32,128}, # Freifunk (Foerderverein Freie Netzwerke) IPv6 Range
    2001:67c:20a1::/48{48,48}, # CCC Event Network
    2001:0470:006c:01d5::/64{64,64}, # Registered IANA
    2001:0470:006d:0655::/64{64,64},
    2001:0470:1f09:172d::/64{64,64},
    2001:0470:1f0b:0592::/64{64,64},
    2001:0470:1f0b:0bca::/64{64,64},
    2001:0470:1f0b:1af5::/64{64,64},
    2001:0470:1f10:0275::/64{64,64},
    2001:0470:1f12:0004::/64{64,64},
    2001:0470:5084::/48{48,64},
    2001:0470:51c6::/48{48,64},
    2001:0470:73d3::/48{48,64},
    2001:0470:7972::/48{48,64},
    2001:0470:9949::/48{48,64},
    2001:0470:99fc::/48{48,64},
    2001:0470:9af8::/48{48,64},
    2001:0470:9ce6::/55{55,64},
    2001:0470:9f43::/48{48,64},
    2001:0470:caab::/48{48,64},
    2001:0470:cd99::/48{48,64},
    2001:0470:d4df::/48{48,64},
    2001:0470:d889:0010::/64{64,64},
    2001:0470:e3f0:000a::/64{64,64},
    2001:067c:21ec::/48{48,64},
    2001:06f8:1019:0000::/64{64,64},
    2001:06f8:118b::/48{48,64},
    2001:06f8:1194::/48{48,64},
    2001:06f8:121a::/48{48,64},
    2001:06f8:1c1b::/48{48,64},
    2001:06f8:1d14::/48{48,64},
    2001:06f8:1d26::/48{48,64},
    2001:06f8:1d53::/48{48,64},
    2001:07f0:3003::/48{48,64},
    2001:08d8:0081:05c8::/63{63,64},  
    2001:08d8:0081:05ca::/64{64,64},
    2001:15c0:1000:0100::/64{64,64},
    2001:1b60:1000:0001::/64{64,64},
    2001:41d0:0001:b6bb::/64{64,64},
    2001:41d0:0001:cd42::/64{64,64},
    2001:4dd0:fcff::/48{48,64},
    2001:4dd0:fdd3::/48{48,64},
    2001:4dd0:ff00:8710::/64{64,64},
    2604:8800:0179:4200::/56{56,64},
    2801:0000:80:8000::/50{50,64},
    2a00:1328:e101:0200::/56{56,64},
    2a00:1828:2000:0289::/64{64,64},
    2a00:1828:a013:d242::/64{64,64},
    2a00:5540:0387::/48{48,64},
    2a01:0198:022c::/48{48,64},
    2a01:0198:035a:fd13::/64{64,64},
    2a01:0198:0485::/48{48,64},
    2a01:04f8:0121:4fff::/64{64,64},
    2a01:04f8:0140:1ffd::/64{64,64},
    2a01:04f8:0d13:17c0::/64{64,64},
    2a02:0a00:e010:3c00::/56{56,64},
    2a02:0ee0:0002:0051::/64{64,64},
    2a03:2260::/30{30,64}
  ];
} 

# /etc/bird/peers6/<PEER_NAME>
protocol bgp <PEER_NAME> from dnpeers {
  neighbor <PEERING_IP> as <PEER_AS>;
  # if you use link-local ipv6 addresses for peering using the following
  # neighbor <PEERING_IP> % '<INTERFACE_NAME>' as <PEER_AS>;
};

IPv4

# /etc/bird/bird.conf
# Device status
protocol device {
  scan time 10; # recheck every 10 seconds
}

protocol static {
  # Static routes to announce your own range(s) in dn42
  route <SUBNET> reject;
  import all;
  export none;
};

# local configuration
######################

# keeping router specific in a seperate file, 
# so this configuration can be reused on multiple routers in your network
include "/etc/bird/local4.conf";

# filter helpers
#################

include "/etc/bird/filter4.conf";

# Kernel routing tables
########################

/*
    krt_prefsrc defines the source address for outgoing connections.
    On Linux, this causes the "src" attribute of a route to be set.
    
    Without this option outgoing connections would use the peering IP which
    would cause packet loss if some peering disconnects but the interface
    is still available. (The route would still exist and thus route through
    the TUN/TAP interface but the VPN daemon would simply drop the packet.)
*/
protocol kernel {
  scan time 20;
  device routes;
  import none;
  export filter {    
    if source = RTS_STATIC then reject;
    krt_prefsrc = OWNIP;
    accept;
  };
};
# DN42
#######

template bgp dnpeers {
  local as OWNAS;
  # metric is the number of hops between us and the peer
  path metric 1;
  # this lines allows debugging filter rules
  # filtered routes can be looked up in birdc using the "show route filtered" command
  import keep filtered;
  import filter {
    # accept every subnet, except our own advertised subnet
    # filtering is important, because some guys try to advertise routes like 0.0.0.0
    if is_valid_network() && !is_self_net() then {
      accept;
    }
    reject;
  };
  export filter {
    # here we export the whole net
    if is_valid_network() then {
      accept;
    }
    reject;
  };
  import limit 10000 action block;
  #source address OWNIP;
};

include "/etc/bird/peers4/*";

#/etc/bird/local4.conf
# should be a unique identifier, <GATEWAY_IP> is what most people use.
router id <GATEWAY_IP>;

define OWNAS =  <AS>;
define OWNIP = <GATEWAY_IP>;

function is_self_net() {
  return net ~ [<SUBNET>+];
}

Generate the filter list from the monotone repository

$ cd net.dn42.registry
$ ruby utils/bgp-filter.rb --format bird < data/filter.txt > /etc/bird/filter4.conf

or

$ curl -sk https://ca.dn42.us/reg/filter.txt | \
    awk '/^[0-9]/ && $2 ~ /permit/ {printf "%s{%s,%s}\n", $3, $4, $5}' | \
    awk 'BEGIN {printf "function is_valid_network() {\n return net ~ [\n"} \
        NR > 1 {printf ",\n"} {printf "  %s", $1}
        END {printf "\n ];\n}\n"}' > /etc/bird/filter4.conf

example filter list:

function is_valid_network() {
  return net ~ [
    172.22.0.0/15{22,28}, # dn42 main net0
    172.20.0.0/16{21,28}, # dn42 main net1
    172.22.0.0/23{28,32}, # dn42 Anycast range
    172.23.0.0/24{28,32}, # dn42 Anycast range
    192.175.48.0/24{24,32}, # AS112-prefix for reverse-dns  
    10.0.0.0/8{12,28}, # freifunk/chaosvpn
    172.31.0.0/16{22,28}, # chaosvpn
    100.64.0.0/10{12,28}, # iana private range
    195.160.168.0/23{23,28}, # ctdo
    91.204.4.0/22{22,28}, # free.de via ctdo
    193.43.220.0/23{23,28}, # durchdieluft via ctdo
    83.133.178.0/23{23,28}, # muccc kapsel
    87.106.29.254/32{32,32}, # wintix (please don' announce /32)
    85.25.246.16/28{28,32}, # leon
    46.4.248.192/27{27,32}, # welterde
    94.45.224.0/19{19,28}, # ccc event network
    151.217.0.0/16{16,28}, # ccc event network 2
    195.191.196.0/23{23,29}, # ichdasich pi space
    80.244.241.224/27{27,32}, # jchome service network
    188.40.34.241/32{32,32},
    37.1.89.192/26{26,28}, # siska
    87.98.246.19/32{32,32}
  ];
}

# /etc/bird/peers4/<PEER_NAME>
protocol bgp <PEER_NAME> from dnpeers {
  neighbor <PEERING_IP> as <PEER_AS>;
};

Bird communities

Communities can be used to prioritize traffic based on different flags, in DN42 we are using communities to prioritize based on latency, bandwidth and encryption. It is really easy to get started with communities and we encourage all of you to get the basic configuration done and to mark your peerings with the correct flags for improved routing. More information can be found here.

Useful bird commmands

bird can be remote controlled via the birdc command. Here is a list of useful bird commands:

$ birdc
BIRD 1.4.5 ready.
bird> configure # reload configuration
Reading configuration from /etc/bird.conf
Reconfigured
bird> show  ? # Completions work either by pressing tab or pressing '?'
show bfd ...                                   Show information about BFD protocol
show interfaces                                Show network interfaces
show memory                                    Show memory usage
show ospf ...                                  Show information about OSPF protocol
show protocols [<protocol> | "<pattern>"]      Show routing protocols
show roa ...                                   Show ROA table
show route ...                                 Show routing table
show static [<name>]                           Show details of static protocol
show status                                    Show router status
show symbols ...                               Show all known symbolic names
bird> show protocols # this command shows your peering status
name     proto    table    state  since       info
device1  Device   master   up     07:20:25    
kernel1  Kernel   master   up     07:20:25    
chelnok  BGP      master   up     07:20:29    Established   
hax404   BGP      master   up     07:20:26    Established     
static1  Static   master   up     07:20:25
bird> show protocols all chelnok # show verbose peering status for peering with chelnok
bird> show route for 172.22.141.181 # show possible routes to internal.dn42
172.22.141.0/24    via 172.23.67.1 on tobee [tobee 07:20:30] * (100) [AS64737i]
                   via 172.23.64.1 on chelnok [chelnok 07:20:29] (100) [AS64737i]
                   via 172.23.136.65 on hax404 [hax404 07:20:26] (100) [AS64737i]
bird> show route filtered # shows routed filtered out by rules
172.23.245.1/32    via 172.23.64.1 on chelnok [chelnok 21:26:18] * (100) [AS76175i]
172.22.247.128/32  via 172.23.64.1 on chelnok [chelnok 21:26:18] * (100) [AS76175i]
172.22.227.1/32    via 172.23.64.1 on chelnok [chelnok 21:26:18] * (100) [AS76115i]
172.23.196.75/32   via 172.23.64.1 on chelnok [chelnok 21:26:18] * (100) [AS76115i]
172.22.41.241/32   via 172.23.64.1 on chelnok [chelnok 21:26:18] * (100) [AS76115i]
172.22.249.4/30    via 172.23.64.1 on chelnok [chelnok 21:26:18] * (100) [AS4242420002i]
172.22.255.133/32  via 172.23.64.1 on chelnok [chelnok 21:26:18] * (100) [AS64654i]
bird> show route protocol <somepeer> # shows the route they export to you
bird> show route export <somepeer> # shows the route you export to someone
...

External Links

• detailed bird configuration from Mic92: https://github.com/Mic92/bird-dn42
• more bgp commands: http://danrimal.net/doku.php?id=wiki:bgp:bird:postupy