Why some Tor servers are slow (was Re: TOR Park Exit Node Question)

[Roger Dingledine <arma@xxxxxxx>]

On Fri, Sep 30, 2005 at 02:04:46PM +0300, Giorgos Pallas wrote:
> >What I mean is, is it normal for the Tonga server to claim over 4 MB of
> >bandwidth ? If so, why are other servers that are on a 100 Mbit link not
> >reporting more bandwidth ?

Tonga is using dual AMD64's. Moria also uses those CPUs. They seem to
be extremely fast at crypto (and everything else).

Tonga also advertises port 80 and 443, so it's useful for people
stuck behind fascist firewalls.

Tonga also opened up its exit policy to attract more traffic. Servers
that have lots of unused capacity, and are fast and have high uptime, and
offer unusual ports like the default file-sharing ports, will bootstrap
themselves by advertising a little bit, attracting more clients, and
so on.

(I'm not sure I actually like the fact that Tonga opened up its file
sharing ports, since it puts more load on the rest of the network too,
but I guess since we're still in development, a little bit of stress
like this can be good for us.)

> >While typing this it occurred to me that the default
> >MaxAdvertisedBandwith is 2 MB and that Tonga has probably set it higher...

Actually, the default MaxAdvertisedBandwidth is 128 TB. I believe
you're thinking of BandwidthRate.

> Whis has also been a question of mine. Why my tor router handles a very 
> low traffic volume (~30 KB in and out) while at the same time has 100% 
> connectivity, 100Mbps of real bandwidth and stays up for more than a 
> week (until it crashes due to memory ;-)... Could anyone help with that? 
> It's frustrating wanting to share (bandwidth in our case) with the 
> community but not being able to do so!

There is something wrong with the masquerade Tor server. You can see it
yourself (you may have to try from someplace other than masquerade's LAN,
though) -- run "telnet 155.207.113.227 9001" and hit enter about 10 times.

Notice how it's really sluggish and takes a long time before it hangs up.

Now run "telnet 82.94.251.206 443" and do the same thing. Notice how it
realizes the ssl handshake has failed after about 5 lines. This is how
it's supposed to be.

So masquerade is somehow not putting much attention into its ssl
handshakes. This could be because its network connection is actually
through a proxy or a firewall that is dropping some of the packets or
slowing things down tremendously. It could also be that it's running on
a 100 mhz 486, or its ulimits are set to something crazy-low, or it's
busy ray-tracing a movie, or something else.

I'd be curious to learn what's up with it. I've seen this behavior before
on Windows machines behind cable modems and crappy NAT boxes.

--Roger