[Galene] Re: About UDP multiplexing

[Dirk-Willem van Gulik <dirkx@webweaving.org>]

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On 22 Mar 2025, at 19:29, Juliusz Chroboczek <jch@irif.fr> wrote:

> By default, Galene will use random UDP ports for media traffic.  If the
> high ports are inaccessible for some reason (say, because there is
> a firewall in the way), it will fall back to routing through the built-in
> TURN server.  While this is the right approach, it makes Galene
> challenging to install for people who wish to put it behind a firewall.
> 
> There is another approach, which is to put all the UDP traffic on a single
> port; this is called UDP multiplexing.  I tried it a couple of years ago,
> and it did not work well, apparently Pion (our WebRTC library) had some
> issues with double-stack hosts when multiplexing.  It appears to work now,
> and I've implemented it in the branch "udpmux".
> 
> UDP muxing is very simple to use: just add the option "-udp 10000", where
> 10000 is the port that you wish to use for UDP traffic.

Works most splendidly. 

I am wondering if the config could be simpler; e.g we now have

	-udp-range 10000:20000

Which clashes (obviously) with this new

	-udp 100000

So perhaps it would be nice to simplify this in one option to:

	-udp-range 10000-20000
	-udp-range 10000

Or - when nothing is specified —  just use any port above 1024.

> There are some caveats:
> 
>  - there is a slight performance penalty, but it should be negligible;
> 
>  - if the server is renumbered (its IP address changes), you will need
>    to restart Galene.
> 
> The code is live on galene.org, and it seems to work fine.  I've
> reimplemented it just today, so if you did test before, please test again.
> 
> Note that UDP muxing, in its current state, does not solve the NAT
> problem: if your server is behind NAT, Galene will still fallback to TURN,
> even if the mux port is forwarded on the NAT.  I'll see if I can implement
> something, but please don't hold your breath, I'm not really interested in
> working around NAT issues.

For what it is worth this works fairly ok with NAT now in a somewhat neutered FreeBSD jail; config below through NAT.

Install is `stock’ freebsd from ports; with just the galene binary swapped for the one from the usbmux branch.

Which comes very close to what is ideal to deploy in a more controlled/enterprise/defence-in-depth sort of setting.

So that is most lovely !

Dw.




Jail - minimal jail with just ‘pkg install galena’ and:

/etc/rc.conf
	galene_enable=yes
	galene_http=127.0.2.1:8888
	galene_args=" -turn $EXT_VISIBLE_IP:1195 -http 127.0.2.1:8888 -insecure -udp 10000 "

Reverse proxy on the outside via apache or nginx (both work):

        
        location /ws {
            proxy_pass http://127.0.2.1:8888/ws;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
        }
        location  / { proxy_pass http://127.0.2.1:8888; }
    

And tied in to normal certificate mngt, logging, etc done entirely outside galene.  If needed - intercepting the web furniture.

With as the firewall setting nothing more than:

/etc/rc.conf:
	pf_enable="YES"
	pf_rules="/etc/pf.conf"

/etc/pfc.conf:

		
	ext_if=“vtnet0"
	set skip on lo
	scrub in all

	turn_range="10000"

	jails="{ 127.0.2.0/24 }"
        galene_jail_ip=127.0.2.1

	# Jails allowed to do any outbound (via NAT)
	jails_outbound="{ $galene_jail_ip }"

	nat pass on $ext_if from $jails_outbound to any -> $ext_vis_ip static-port

	rdr pass on $ext_if proto {udp,tcp} from any to $ext_jail_ip port 1195        -> $galene_jail_ip
	rdr pass on $ext_if proto {udp,tcp} from any to $ext_jail_ip port $turn_range -> $galene_jail_ip

	….
	pass in on $ext_if proto tcp          to { $ext_vis_ip } port { http, https } keep state # HTTP reverse proxy (ngix)
	pass in on $ext_if proto { tcp, udp } to { $ext_vis_ip } port 1195 keep state		# Turn
	pass in on $ext_if proto { udp, tcp } to { $ext_vis_ip } port $turn_range keep state	# RTP






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