BIRD_RTBH_Example

# Configure logging
#log "/var/log/bird-rtbh.log" all;
log syslog { debug, trace, info, remote, warning, error, auth, fatal, bug };

define local_asn = 65001;

# Override router ID
router id 10.0.0.100;

# This pseudo-protocol performs synchronization between BIRD's routing
# tables and the kernel. If your kernel supports multiple routing tables
# (as Linux 2.2.x does), you can run multiple instances of the kernel
# protocol and synchronize different kernel tables with different BIRD tables.
protocol kernel {
       learn;                  # Learn all alien routes from the kernel
        persist;                # Don't remove routes on bird shutdown
        scan time 20;           # Scan kernel routing table every 20 seconds
        import none;            # Default is import all
        export none;             # Default is export none
        kernel table 5;         # Kernel table to synchronize with (default: main)
}

table RTBH;
protocol kernel rtbh {
		learn;
        persist;                
        scan time 20;           
        import all;            
        export all;    
        table RTBH;         
        kernel table 100;         # Kernel table to synchronize with (rtbh: 100)
}

# This pseudo-protocol watches all interface up/down events.
protocol device {
        scan time 10;           # Scan interfaces every 10 seconds
}

# Allow only /32 part of a specific prefix
# This function will only pass if the prefix is a /32 and part of the allowed_prefix list
function check_prefix()
prefix set allowed_prefix;
{
    allowed_prefix = [ 203.0.113.128/25+, 1.1.1.0/24+ ];

    if ! (net ~ allowed_prefix) then return false;
    if net.len != 32 then return false;

    return true;
}

#This Filter will be applied to BGP Export, it will check if check_prefix() is True and then set the Blackhole Community
filter EXPORT_BLACKHOLED_32
{
    if ! (check_prefix()) then
        reject;

    bgp_community = -empty-;    
    bgp_community.add((local_asn,666));

    accept;
}

#Peer BGP Settings. We explicity select table RTBH, which makes this BGP Peer sync with the Kernel Table RTBH Only.
protocol bgp EDGE {
	   table RTBH;
       description "Peer with Edge Router to announce /32 Prefixes to be Blackholed";
       local as local_asn;
       neighbor 10.0.0.1 as local_asn;
       import all;
       export filter EXPORT_BLACKHOLED_32;
}