我比较白痴，首先澄清一个概念，使用Bridge和作为Bridge是两个概念。
- 使用Bridge是指作为client，使用已有的Bridge连接到网络。
- 作为Bridge是指把自己变成一个Bridge server。
貌似不能既使用Bridge又作为Bridge。:(
使用Bridge很简单，发送邮件给bridges@torproject.org，邮件title为get bridges，就可以收到一个回复，大概是这样的：
[This is an automated message; please do not reply.]
Here are your bridge relays:
bridge 85.176.137.125:443
bridge 125.121.20.246:9002
bridge 79.182.101.170:8080Bridge relays (or “bridges” for short) are Tor relays that aren’t listed
in the main directory. Since there is no complete public list of them,
even if your ISP is filtering connections to all the known Tor relays,
they probably won’t be able to block all the bridges.To use the above lines, go to Vidalia’s Network settings page, and click
“My ISP blocks connections to the Tor network”. Then add each bridge
address one at a time.Configuring more than one bridge address will make your Tor connection
more stable, in case some of the bridges become unreachable.Another way to find public bridge addresses is to visit
https://bridges.torproject.org/. The answers you get from that page
will change every few days, so check back periodically if you need more
bridge addresses.
把里面那几行bridge列表加到/etc/tor/torrc文件的最后，再加上一行UseBridges 1。重启tor，如果同时使用privoxy的话把它也重启一下好了。现在的FireFox根本就不需要这个东西了，可以直接使用socket代理。
作为Bridge的话，在/etc/tor/torrc里加上这么几行：
SocksPort 0
ORPort 443
BridgeRelay 1
Exitpolicy reject *:*
自己对照着看看，不要直接加上去。
为什么不作为一个normal relay呢？因为从我们这里出去的话不是在浪费其它人时间么！所以Bridge就行，不要直接出去。