[tor-relays] running multiple bridges on one machine?

[Steve Snyder]

On Monday, April 27, 2015 9:30pm, "syndikal" <syndikal at riseup.net> said:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA512
> 
> hello relay operators!
> 
> i've asked this question on IRC once or twice, but it seems the right
> people aren't online/active when i am. i think i might be able to get a
> better audience to answer my questions here on the mailing lists.
> 
> let's begin: is it possible to run 5 bridges on one low-end VPS? each
> bridge would be hosted on a different IP address from five different /24
> IP blocks, so that's not an issue. would i have to use multiple Tor
> processes, and would 5 processes be too much for a 2-core VPS with
> 256mb memory?

There is no way you will squeeze 5 bridges into 256MB.  256MB is more suitable for 2 bridges; 384MB+ is needed if you also want to run an obfsproxy on each bridge.

Really, even 256MB alone is not enough for 2 bridges.  If you do not have swap space too (not a given if your VPS is OpenVZ) you will have to kill the bridges to install OS updates, etc.

CPU utilization isn't a problem.  Some (or even all!) of those bridges will get no real traffic, just a few megabytes/month for housekeeping.  You really won't see much competition for CPU time, especially if your CPUs support the x86 AES instructions (not a given even on contemporary CPUs with KVM).
 
> also, how much bandwidth does a bridge normally burn through per month?
> on said VPS, the economical choice is to provide 200gb bandwidth per
> month. if that is not sufficient, the offer isn't financially feasible.

I've seen it vary from no traffic at all up to a terabyte per month.  It really all depends on how your bridges are distributed and how heavily the bridges are used by those who receive the distribution. 

I guess you could manage the bridge use by handing out the addresses yourself, but if you rely on the normal bridge distribution methods, it is really out of your hands.