Created OpenBGPd (markdown) - initial draft

howto/OpenBGPD.md

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+This guide describes a simple configuration for [OpenBGPD](https://openbgpd.org) running on [OpenBSD](https://openbsd.org).
+The [portable version](https://openbgpd.org/ftp.html) should run with little to no configuration changes on other operating systems as well.
+
+# Setup
+Only IPv6 is used for the sake of simplicity.
+Neighbors use ULA addresses (/127 transfer net) assigned from one of the peer's allocation.
+
+The goal is to have a small, yet complete setup for all peers with ROA validation and other safety measurements in place.
+
+# Configuration
+[`/etc/bgpd.conf`](https://man.openbsd.org/bgpd.conf.5) contains all information and includes generated pieces such as ROA sets;  see the `ROA` section in this guide.
+
+As per the manual, configuration is divided into logical sections;  [`/etc/examples/bgpd.conf`](http://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/etc/examples/bgpd.conf?rev=HEAD&content-type=text/plain&only_with_tag=MAIN) is a complete and commented example which this guide is roughly based on.
+
+By default, **bgpd** listens on all local addresses (on the current default [`routing domain`](http://man.openbsd.org/rdomain.4)), but this guide explicitly listens on the configured transfer ULA only for each peer to better illustrate of this setup.
+
+## local peer
+Information such as ASN, router ID and allocated networks are required:
+```
+# macros
+ASN="4242421234"
+
+# global configuration
+AS $ASN
+router-id 1.2.3.4
+
+prefix-set mynetworks {
+        fd00:12:34::/48
+}
+```
+
+These can be used in subsequent filter rules.
+The local peer's announcements is then defined as follows:
+```
+# 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 $ASN:1:1
+```
+
+## neighbors
+For each neighbor its ASN and transfer ULA is required.
+An optional description is provided such that [`bgpctl`](http://man.openbsd.org/bgpctl.8) for example can be used with mnemonic names instead of AS numbers:
+```
+$peerA-local="fd00:12:34:A::1"
+$peerA-remote="fd00:12:34:A::2"
+$peerA-ASN="4242425678"
+
+listen on $peerA-local
+neighbor  $peerA-remote {
+    remote-as $peerA-ASN
+    descr "peerA"
+}
+```
+
+# ROA
+
+# Looking glass