bgpd.conf

# $OpenBSD: bgpd.conf,v 1.22 2023/09/27 10:49:21 claudio Exp $
# example bgpd configuration file, see bgpd.conf(5)

# define our own ASN as a macro
ASN="65001"

# global configuration
AS $ASN
router-id 192.0.2.1

# list of networks that may be originated by our ASN
prefix-set mynetworks {
	192.0.2.0/24
	2001:db8:abcd::/48
}

include "/var/db/rpki-client/openbgpd"

# define bogon prefixes which should not be part of the DFZ
prefix-set bogons {
	0.0.0.0/8 or-longer		# 'this' network [RFC1122]
	10.0.0.0/8 or-longer		# private space [RFC1918]
	100.64.0.0/10 or-longer		# CGN Shared [RFC6598]
	127.0.0.0/8 or-longer		# localhost [RFC1122]
	169.254.0.0/16 or-longer	# link local [RFC3927]
	172.16.0.0/12 or-longer		# private space [RFC1918]
	192.0.2.0/24 or-longer		# TEST-NET-1 [RFC5737]
	192.88.99.0/24 or-longer	# 6to4 anycast relay [RFC7526]
	192.168.0.0/16 or-longer	# private space [RFC1918]
	198.18.0.0/15 or-longer		# benchmarking [RFC2544]
	198.51.100.0/24 or-longer	# TEST-NET-2 [RFC5737]
	203.0.113.0/24 or-longer	# TEST-NET-3 [RFC5737]
	224.0.0.0/4 or-longer		# multicast
	240.0.0.0/4 or-longer		# reserved for future use
	::/8 or-longer			# RFC 4291 IPv4-compatible, loopback, et al
	0100::/64 or-longer		# Discard-Only [RFC6666]
	2001:2::/48 or-longer		# BMWG [RFC5180]
	2001:10::/28 or-longer		# ORCHID [RFC4843]
	2001:db8::/32 or-longer		# docu range [RFC3849]
	2002::/16 or-longer		# 6to4 anycast relay [RFC7526]
	3ffe::/16 or-longer		# old 6bone
	fc00::/7 or-longer		# unique local unicast
	fe80::/10 or-longer		# link local unicast
	fec0::/10 or-longer		# old site local unicast
	ff00::/8 or-longer		# multicast
}

# Generate routes for the networks our ASN will originate.
# The communities (read 'tags') are later used to match on what
# is announced to EBGP neighbors
network prefix-set mynetworks set large-community $ASN:1:1

# assume simple network with 3 routers in IBGP full mesh
group "ibgp mesh" {
	remote-as $ASN
	# use loopback for IBGP sessions, assume it's distributed in OSPF
	local-address 192.0.2.1
	local-address 2001:db8:abcd::1

	neighbor 192.0.2.2		# router 2 ipv4
	neighbor 2001:db8:abcd::2	# router 2 ipv6
	neighbor 192.0.2.3		# router 3 ipv4
	neighbor 2001:db8:abcd::3	# router 3 ipv6
}

# upstream providers
group "upstreams" {
	neighbor 203.0.113.1 {
		remote-as 65002
		descr "upstream1"
	}
	neighbor 198.51.100.0 {
		remote-as 65123
		descr "upstream2-4"
	}
	neighbor 2001:db8:666::2 {
		remote-as 65123
		descr "upstream2-6"
	}
}

## rules section

# uncomment the following two lines to accept a default route from upstreams
#allow from group upstreams prefix 0.0.0.0/0
#allow from group upstreams prefix ::/0

### for simple BGP setups, no editing below this line is required ###

# Outbound EBGP: only allow self originated networks to ebgp peers
# Don't leak any routes from upstream or peering sessions. This is done
# by checking for routes that are tagged with the large-community $ASN:1:1
allow to ebgp prefix-set mynetworks large-community $ASN:1:1

# deny more-specifics of our own originated prefixes
deny quick from ebgp prefix-set mynetworks or-longer

# IBGP: allow all updates to and from our IBGP neighbors
allow from ibgp
allow to ibgp

# Scrub normal and large communities relevant to our ASN from EBGP neighbors
# https://tools.ietf.org/html/rfc7454#section-11
match from ebgp set { community delete $ASN:* }
match from ebgp set { large-community delete $ASN:*:* }

# filter out prefixes longer than 24 or shorter than 8 bits for IPv4
# and longer than 48 or shorter than 16 bits for IPv6.
allow from any inet prefixlen 8 - 24
allow from any inet6 prefixlen 16 - 48

# Honor requests to gracefully shutdown BGP sessions
# https://tools.ietf.org/html/rfc8326
match from ebgp community GRACEFUL_SHUTDOWN set { localpref 0 }

deny quick from any prefix-set bogons

# deny RPKI invalid, built by rpki-client(8), see root crontab
deny quick from ebgp ovs invalid

# filter bogon AS numbers
# AS_TRANS (23456) is not supposed to show up in any path and indicates a
# misconfiguration. Additionally Private or Reserved ASNs have no place in
# the public DFZ. https://www.iana.org/assignments/as-numbers/as-numbers.xhtml
deny quick from any AS 23456
deny quick from any AS 64496 - 131071
deny quick from any AS 4200000000 - 4294967295

# filter out too long paths
deny from any max-as-len 100