[tor-relays] Enabling obfs4 and obfs3 on 80 and 443

[R-one]

I have recently set up a bridge and was reading some old emails on the 
list.  I found some instructions from s7r on setting up obfs4 and obfs3:

> Sample torrc entry for enabling obfs4 and obfs3:
> ExtORPort auto
> ServerTransportPlugin obfs3,obfs4 exec /usr/bin/obfs4proxy
> ServerTransportListenAddr obfs3 [::]:port
> ServerTransportListenAddr obfs4 [::]:port
>
> To make the bridge even better, you can bind obfs3 and obfs4 to lower
> ports (< 1024), if you have them free, such as obfs3 on 80 and obfs4
> on 443 (for example).

This seemed like a good idea (I am not running a web server).

I am running tor 0.2.4.27, which does not seem to support ExtORPort.  
 From some other recommended bridge setup I had previously set ORPort to 
443.  I tried changing my config to:

ORPort auto
ServerTransportListenAddr obfs3 0.0.0.0:80
ServerTransportListenAddr obfs4 0.0.0.0:443

(and doing the capabilities stuff, of course).

This didn't work -- obfs4 complained that 443 was in use (is that 
because I had previously set it for ORPort?).  So, for now, I have set 
obfs4 to a random high port.

I will admit to being pretty confused about the recommended bridge 
setting for ORPort and the obfs ports (and what ExtORPort does 
differently).  Does anyone have a recommendation for what I should do?  
Do I need to upgrade to tor 0.2.5?