OpenWRT: OLSR nameservice plugin

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Reference: https://github.com/servalproject/olsr/blob/master/lib/nameservice/README_NAMESERVICE


NAMESERVICE PLUGIN FOR OLSRD

by Bruno Randolf <bruno.randolf@4g-systems.biz>


a simple DNS replacement for OLSR networks

this plugin distributes host name (DNS) information over OLSR. every node which runs the olsr daemon can announce it's own name, names for other IP adresses it is associated with (HNAs) and if it is running a "real" nameserver which can resolve other (internet) names (upstream dns server).

the nodes in the network collect this information and write the host names to a file (possibly /etc/hosts), and the 3 nearest upstream nameservers to another file (possibly /etc/resolv.conf).

these files can be used to resolve hostnames on the local system and/or be read by a DNS server like "dnsmasq", to make the names available via the ordinary DNS protocol to other clients as well.

the default location of the hosts file is "/var/run/hosts_olsr" on unixes "C:\WINDOWS\hosts_olsr" on windows


PLUGIN PARAMETERS (PlParam)

PlParam "name" "my-name.mesh"
	the name of this OLSR node (main address).
	can be specified multiple times for different names.

PlParam "IP.ADDR" "another-name.mesh"
	a name for a specified IP address.
	the IP address has to be either from one of the olsr 
	interfaces or within a HNA network we announce.
	can be specified multiple times.

PlParam "hosts-file" "/path/to/hosts_file"
	which file to write to (usually /etc/hosts).
	(default: /var/run/hosts_olsr)

PlParam "suffix" ".olsr"
	local suffix which is appended to all received names.
	(default: "")

PlParam "add-hosts" "/path/to/file"
	copy contents of this additional hosts file to output file.
	this is practical if you alreay use your /etc/hosts file.

PlParam "dns-server" "IP.ADDR"
	anounce that this IP has a full (upstream) DNS server. if 
	IP.ADDR is not specified (""), the main address is used.
	nodes which don't know a nameserver will automatically use
	this nameserver.

PlParam "resolv-file" "/path/to/resolv.conf"
	path to resolv.conf file (usually /etc/resolv.conf)
	if set, the 3 nearest (best ETX) upstream nameservers annonced 
	by other nodes in the network are written to this file

PlParam "interval" "SEC"
	interval for sending NAME messages in seconds.
	(default: 120 - 2 minutes)

PlParam "timeout" "SEC"
	validity time for received NAME messages in seconds.
	(default: 3600 - 1 hour)

PlParam "lat" "12.123"
	Float: Decimal latitude for this node to be flooded in the mesh

PlParam "lon" "12.123"
	Float: Decimal longitude for this node to be flooded in the mesh

PlParam "latlon-file" "/var/run/latlon.js"
	Filename to write Javascript statements to. Default is "latlon.js"
	(either /var/run or windows directory). This file is written, if
	the "lat" and "lon" parameters are set. It has this format:

	/* One or more mid-aliases of multihomed nodes */
	Mid('fromip','toip');

	/* One special Node() entry for this node
	 * defhna means: This node announces hna 0.0.0.0/0
	 * defroute means: The current neighbour IP for 0.0.0.0/0
	 */
	Self('mainip',lat,lon,defhna?1:0,'defroute','name');

	/* One or more node entires for other nodes */
	Node('mainip',lat,lon,this-node-defhna?1:0,'defroute','name');

	/* One or more links between nodes */
	Link('fromip','toip',lq,nlq,etx);

PlParam "latlon-infile" "name-of-input.txt"
	Filename to read lat/lon positions from. Meant to be used
	by a walking GPS receiver. Just write comma separated decimal
	latitude and longitude to this file. Will overwrite the
	"lat" and "lon" parameters during runtime.

PlParam "sighup-pid-file" "/path/to/pidfile.pid"
        (*nix systems only) Sends a HUP signal to the process specified
        by the pidfile (usually /var/run/dnsmasq.pid) when the host name
        table changes. This is useful for letting dnsmasq or bind know
        they have to reload their hosts file.

PlParam "name-change-script" "/path/to/script"
        Script to execute when there is a change in the hosts names
        table. Useful for executing a script that uses the hosts file
        to keep a website or a database updated.

PlParam "service" "http://me.olsr:80%7Ctcp%7Cmy little homepage"
        Add a new service announcement to be spreaded in the mesh.

P lParam "services-file" "/path/to/services_file" 

	File to write (default: /var/run/services_olsr)

PlParam "services-change-script" "/path/to/script"
        Similar to the previous parameter. Script to execute when there
        is a change in the services list propagated by the nameserver
        plugin. Useful for executing a script that uses the services file
        to keep a website or a database updated.

PlParam "mac" "xx:xx:xx:xx:xx:xx[,0-255]"
        Add a new MAC addr to be spreaded in the mesh. This MAC addr
        may be used to fine control nerve-wreck-page solutions based
        on MAC adresses. The optional dec. number designates a class.

PlParam "macs-file" "/path/to/macs_file"
	File to write (default: /var/run/macs_olsr)

PlParam "macs-change-script" "/path/to/script"
        Similar to the previous parameter. Script to execute when there
        is a change in the macs list propagated by the nameserver
        plugin. Useful for executing a script that uses the services file
        to keep a website or a database updated.

SAMPLE CONFIG

add in /etc/olsrd.conf: 

LoadPlugin "olsrd_nameservice.so.0.3"
{
	PlParam "name" "thisismyname"
	PlParam "hosts-file" "/etc/hosts"
	PlParam "resolv-file" "/etc/resolv.conf"
}

USING THE NAME INFORMATION

to use the name information distributed by the plugin actually for name resolution you can do one of the following.

UNIX VARIANTS: 

* overwrite /etc/hosts
	be sure you have nothing in /etc/hosts which you still need and
	configure the plugin with PlParam "host-file" "/etc/hosts"

* link /etc/hosts
	ln -s /var/run/hosts_olsr /etc/hosts

* use dnsmasq
	if you want to make the names available via ordinary DNS
	you can use dnsmasq to read the hosts file and serve it to
	users. add "addn-hosts=/var/run/hosts_olsr" to dnsmasq.conf 
        and:
              PlParam "sighup-pid-file" "/var/run/dnsmasq.pid"

        to your nameservice plugin configuration.

        This is especially usefull for infrastructure mesh networks that
        can't afford to run olsrd on all the clients but wish to provide
        DNS to them. This is solved by running dnsmasq and olsrd with
        this setup on "edge" nodes that provide connectivity.

WINDOWS: 

* overwrite C:\WINDOWS\system32\drivers\etc\hosts
	be sure you have nothing in the file which you still need 
	and configure the plugin with
        PlParam "hosts-file" "C:\WINDOWS\system32\drivers\etc\hosts"

TODO

  • implement a small DNS server into the plugin?
  • or make dynamic DNS updates for bind?



Referensi

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