How to configure External BGP with Bird?

Recently, I need to study about Calico over Kubernetis. In fact, I like Flannel rather than this. However, this Calico is also best practice. During start this Calico, I read about the Brid. In this post, I will how to install and configure this Bird.

 

1. What is Bird?

In this site, it is explained "what kinds of dynamic routing is supported?". It is working on Linux also. In my environment, I will use Ubuntu.

 

2. Install the Bird

I will follow this instruction, It show the best way to install like below. I will use first one.

To add the repository for bird, I refer to this instruction,

# sudo add-apt-repository ppa:cz.nic-labs/bird # sudo apt-get update # apt-get install bird

After then, I can verify the version like below.

 

3. Configuration for Bird for the system

There are servaral configuration to work as the router or switch. First I will edit the system file "/etc/sysctl.conf". 

# vi /etc/sysctl.conf # Uncomment the next line to enable packet forwarding for IPv4 net.ipv4.ip_forward=1 # sysctl -p /etc/sysctl.conf net.ipv4.ip_forward = 1

I will edit some configure for logging in "/etc/bird/bird.conf". In this file, it is look like below default. I will follow this instruction.

# Change this into your BIRD router ID. It's a world-wide unique identification # of your router, usually one of router's IPv4 addresses. router id 198.51.100.1; # The Kernel protocol is not a real routing protocol. Instead of communicating # with other routers in the network, it performs synchronization of BIRD's # routing tables with the OS kernel. protocol kernel {         scan time 60;         import none; #       export all;   # Actually insert routes into the kernel routing table } # The Device protocol is not a real routing protocol. It doesn't generate any # routes and it only serves as a module for getting information about network # interfaces from the kernel.  protocol device {         scan time 60; } # logging log syslog { debug, trace, info, remote, warning, error, auth, fatal, bug }; log stderr all; log "/var/log/bird.log" all;

The bold above will be added. However, sometimes you will get the error message like below. Thus In my case I will update file properties.

# chmod 777 /var/log/bird.log

Now I can start this bird.

# systemctl restart bird # systemctl enable bird # ps aux | grep -i bird bird       796  0.0  0.2  15724  2556 ?        Ss   07:33   0:00 /usr/sbin/bird6 -f -u bird -g bird root      1167  0.0  0.1  14856  1116 pts/0    S+   07:37   0:00 grep --color=auto -i bird

4. Configure the simple BGP routing

This is my environment. I have 2 instance, which have IP address like below. I need to edit "/etc/bird/bird.conf" file

In the default configuration, there is something important variable. 

protocol kernel {         scan time 60;         import none; #       export all;   # Actually insert routes into the kernel routing table } # The Device protocol is not a real routing protocol. It doesn't generate any # routes and it only serves as a module for getting information about network # interfaces from the kernel.  protocol device {         scan time 60; }

For the Simple BGP configuration, I will follow this sample instruction. I will try to configure I-BGP which mean each host has same as number. 

Host #1	Host #2
# BGP Routing Protocol protocol static static_bgp {          route 1.1.1.1:255.255.255.255 via 10.10.0.159;          route 1.1.1.2:255.255.255.255 via 10.10.0.159;  } protocol bgp {         import all;         export where proto = "static_bgp";         local as 65001;         neighbor 10.10.0.205 as 65001; }	# BGP Routing Protocol  protocol static static_bgp {          route 2.2.2.1:255.255.255.255 via 10.10.0.205;          route 2.2.2.2:255.255.255.255 via 10.10.0.205;  } protocol bgp {         import all;         export where proto = "static_bgp";         local as 65001;         neighbor 10.10.0.159 as 65001; }

In my senario, I will announce the loopback IP address into the BGP routing protocol. "export" is look like "redestribute" option. In the above there is some important option "import" and "export". In this instruction, there is some explain like below.

I need to install into the BGP routing table which received. I need to edit "import all". Now I can verify the status with "birdc" command.

Host #1	Host #2
root@ip-10-10-0-159:~# birdc BIRD 1.6.8 ready. bird> show route 1.1.1.1/32         via 10.10.0.159 on ens5 [static_bgp 12:08:06] * (200) 2.2.2.2/32         via 10.10.0.205 on ens5 [bgp1 12:08:11] * (100) [AS65002i] 1.1.1.2/32         via 10.10.0.159 on ens5 [static_bgp 12:08:06] * (200) 2.2.2.1/32         via 10.10.0.205 on ens5 [bgp1 12:08:11] * (100) [AS65002i]	root@ip-10-10-0-205:~# birdc BIRD 1.6.8 ready. bird> show route 2.2.2.2/32         via 10.10.0.205 on ens5 [static_bgp 12:07:51] * (200) 1.1.1.1/32         via 10.10.0.159 on ens5 [bgp1 12:08:11] * (100) [AS65001i] 2.2.2.1/32         via 10.10.0.205 on ens5 [static_bgp 12:07:51] * (200) 1.1.1.2/32         via 10.10.0.159 on ens5 [bgp1 12:08:11] * (100) [AS65001i]

I can see the BGP routing table "1.1.1.1", "1.1.1.2", "2.2.2.1" and "2.2.2.2" are updated. Also I can see the status with "show protocols all" command

bird> show protocols all  name     proto    table    state  since       info kernel1  Kernel   master   up     12:08:06       Preference:     10   Input filter:   ACCEPT   Output filter:  REJECT   Routes:         0 imported, 0 exported, 0 preferred   Route change stats:     received   rejected   filtered    ignored   accepted     Import updates:              0          0          0          0          0     Import withdraws:            0          0        ---          0          0     Export updates:              6          0          6        ---          0     Export withdraws:            0        ---        ---        ---          0 device1  Device   master   up     12:08:06       Preference:     240   Input filter:   ACCEPT   Output filter:  REJECT   Routes:         0 imported, 0 exported, 0 preferred   Route change stats:     received   rejected   filtered    ignored   accepted     Import updates:              0          0          0          0          0     Import withdraws:            0          0        ---          0          0     Export updates:              0          0          0        ---          0     Export withdraws:            0        ---        ---        ---          0 static_bgp Static   master   up     12:08:06       Preference:     200   Input filter:   ACCEPT   Output filter:  REJECT   Routes:         2 imported, 0 exported, 2 preferred   Route change stats:     received   rejected   filtered    ignored   accepted     Import updates:              2          0          0          0          2     Import withdraws:            0          0        ---          0          0     Export updates:              0          0          0        ---          0     Export withdraws:            0        ---        ---        ---          0 bgp1     BGP      master   up     12:08:11    Established      Preference:     100   Input filter:   ACCEPT   Output filter:  (unnamed)   Routes:         2 imported, 2 exported, 2 preferred   Route change stats:     received   rejected   filtered    ignored   accepted     Import updates:              2          0          0          0          2     Import withdraws:            0          0        ---          0          0     Export updates:              4          2          0        ---          2     Export withdraws:            0        ---        ---        ---          0   BGP state:          Established     Neighbor address: 10.10.0.205     Neighbor AS:      65002     Neighbor ID:      10.10.0.205     Neighbor caps:    refresh enhanced-refresh restart-aware llgr-aware AS4     Session:          external AS4     Source address:   10.10.0.159     Hold timer:       186/240     Keepalive timer:  52/80

 

5. Installing over the Kernal Routing table

Even if bird has the routing table, I can not see the routing table over the system. 

root@ip-10-10-0-159:~# netstat -nr Kernel IP routing table Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface 0.0.0.0         10.10.0.1       0.0.0.0         UG        0 0          0 ens5 10.10.0.0       0.0.0.0         255.255.255.0   U         0 0          0 ens5 10.10.0.1       0.0.0.0         255.255.255.255 UH        0 0          0 ens5

Because of this, It is not easy to verify the status if this routing work or not. I need to edit "/etc/bird/bird.conf"

protocol kernel {         scan time 60;         import all;         export all; }

After then, the routing table will be like below.

Host #1

Host #2

root@ip-10-10-0-159:~# netstat -nr Kernel IP routing table Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface 0.0.0.0         10.10.0.1       0.0.0.0         UG        0 0          0 ens5 1.1.1.1         10.10.0.159     255.255.255.255 UGH       0 0          0 ens5 1.1.1.2         10.10.0.159     255.255.255.255 UGH       0 0          0 ens5 2.2.2.1         10.10.0.205     255.255.255.255 UGH       0 0          0 ens5 2.2.2.2         10.10.0.205     255.255.255.255 UGH       0 0          0 ens5 10.10.0.0       0.0.0.0         255.255.255.0   U         0 0          0 ens5 10.10.0.1       0.0.0.0         255.255.255.255 UH        0 0          0 ens5

root@ip-10-10-0-205:~# netstat -nr Kernel IP routing table Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface 0.0.0.0         10.10.0.1       0.0.0.0         UG        0 0          0 ens5 1.1.1.1         10.10.0.159     255.255.255.255 UGH       0 0          0 ens5 1.1.1.2         10.10.0.159     255.255.255.255 UGH       0 0          0 ens5 2.2.2.1         10.10.0.205     255.255.255.255 UGH       0 0          0 ens5 2.2.2.2         10.10.0.205     255.255.255.255 UGH       0 0          0 ens5 10.10.0.0       0.0.0.0         255.255.255.0   U         0 0          0 ens5 10.10.0.1       0.0.0.0         255.255.255.255 UH        0 0          0 ens5

I will use the AWS instance. To verify I need to change the option, "source and destination checking option". This option will drop the packet when the source and destination does not match.

And then, I can transfer ICMP packet like below.

Host #1	Host #2

This is the simple BGP routing with Bird. If I have chance to learn more deep-dive. I will handle about it next time. 

Reference 

[ 1 ] https://bird.network.cz/

[ 2 ] https://gitlab.labs.nic.cz/labs/bird

[ 3 ] https://launchpad.net/~cz.nic-labs/+archive/ubuntu/bird

[ 4 ] https://bird.network.cz/pipermail/bird-users/2011-September/002425.html

[ 5 ] https://blog.marquis.co/configuring-bgp-using-bird-on-ubuntu-14-04lts/

[ 6 ] https://skyenet.tech/bird/