blob: 53b1524f896a49a6e5c53c45c0b99687dc384b64 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
```
Filename: 232-pluggable-transports-through-proxy.txt
Title: Pluggable Transport through SOCKS proxy
Author: Arturo Filastò
Created: 28 February 2012
Status: Closed
Implemented-In: 0.2.6
Overview
Tor introduced Pluggable Transports in proposal "180 Pluggable
Transports for circumvention".
The problem is that Tor currently cannot use a pluggable transport
proxy and a normal (SOCKS/HTTP) proxy at the same time. This has
been noticed by users in #5195, where Tor would be failing saying
"Unacceptable option value: You have configured more than one proxy
type".
Trivia
This comes from a discussion that came up with Nick and I promised
to write a proposal for it if I wanted to hear what he had to say.
Nick spoke and I am writing this proposal.
Acknowledgments
Most of the credit goes to Nick Mathewson for the main idea and
the rest of it goes to George Kadianakis for helping me out in writing
it.
Motivation
After looking at some options we decided to go for this solution
since it guarantees backwards compatibility and is not particularly
costly to implement.
Design overview
When Tor is configured to use both a pluggable transport proxy and a
normal proxy it should delegate the proxying to the pluggable
transport proxy.
This can be achieved by specifying the address and port of the normal
proxy to the pluggable transport proxy using environment variables:
When both a normal proxy and the ClientTransportPlugin directives
are set in the torrc, Tor should put the address of the normal proxy
in an environment variable and start the pluggable transport
proxy. When the pluggable transport proxy starts, it should read the
address of the normal proxy and route all its traffic through it.
After connecting to the normal proxy, the pluggable transport proxy
notifies Tor whether it managed to connect or not.
The environment variables also contain the authentication
credentials for accessing the proxy.
Specifications: Tor Pluggable Transport communication
When Tor detects a normal proxy directive and a pluggable transport
proxy directive, it sets the environment variable:
"TOR_PT_PROXY" -- This is the address of the proxy to be used by
the pluggable transport proxy. It is in the format:
<proxy_type>://[<user_name>][:<password>][@]<ip>:<port>
ex. socks5://tor:test1234@198.51.100.1:8000
socks4a://198.51.100.2:8001
Acceptable values for <proxy_type> are: 'socks5', 'socks4a' and 'http'.
If no <password> can be specified (e.g. in 'socks4a'), it is left out.
If the pluggable transport proxy detects that the TOR_PT_PROXY
environment variable is set, it attempts connecting to it. On
success it writes to stdout: "PROXY DONE".
On failure it writes: "PROXY-ERROR <errormessage>".
If Tor does not read a PROXY line or it reads a PROXY-ERROR line
from its stdout and it is configured to use both a normal proxy and
a pluggable transport it should kill the transport proxy.
```
|
