[Libtorrent-devel] Port range vs. just one port

[Evgeniy Karyakin]

Thanks for clarification, Michael.

Michael Alger wrote:

> On Mon, Mar 12, 2007 at 02:35:41PM +0300, Evgeniy Karyakin wrote:
>> 2007/3/7, markus reichelt <ml at mareichelt.de>:
>>> Ezequiel Birman <ezebirman at yahoo.com.ar> wrote:
>>>> I have set 'port_range = 55557-55557' in .rtorrent.rc
>>>>
>>>> 1) It's ok to use just one port or should I open more?
>>> It's ok, I'm also using only one port.
>> That way you won't let incoming connections to be made. You'll be
>> able to download files and upload it back to peers that *you* have
>> connected to, but others won't be able to connect to you. It's a
>> little bit unfair.
>> Or am I getting it wrong?
> 
> The example above will cause rtorrent to use a single listening port
> for all torrents (55557). This doesn't cause problems because each
> torrent is identified by its magic hash value, which tends to be
> pretty unique.  I'm not sure why the official client uses a
> different port for each torrent; possibly it's a debugging aide.
> 
> A larger port range increases the chances that rtorrent will find an
> unbound port it can use. This can be useful if you have several
> programs using the same port range for inbound connections.
> 
> A less likely benefit to using a larger port range is that it can
> randomise the ports you use for torrent traffic, which might be
> helpful if you want to avoid traffic analysis (on the other hand if
> everyone you connect to uses the standard port that won't help you
> much). It might also help performance if you have very large numbers
> of connections, but I'm not sure about that one.