0 - Operation successfully completed (connection was closed by one of peers)
1-9 - AUTHENTICATION ERRORS
1 - Access denied by ACL (deny)
2 - Redirection (should not appear)
3 - No ACL found, denied by default
4 - auth=strong and no username in request
5 - auth=strong and no matching username in configuration
6 - User found, wrong password (cleartext)
7 - User found, wrong password (crypt)
8 - User found, wrong password (NT)
9 - Redirection data not found (should not appear)
10 - Traffic limit exceeded
11-19 - CONNECTION ERRORS
11 - failed to create socket()
12 - failed to bind()
13 - failed to connect()
14 - failed to getpeername()
20-29 - COMMON ERRORS
21 - memory allocation failed
30-39 - CONNECT PROXY REDIRECTION ERRORS
31 - failed to request HTTP CONNECT proxy
32 - CONNECT proxy connection timed out or wrong reply
33 - CONNECT proxy fails to establish connection
34 - CONNECT proxy timed out or closed connection
40-49 - SOCKS4 PROXY REDIRECTION ERRORS
50-69 - SOCKS5 PROXY REDIRECTION ERRORS
70-79 - PARENT PROXY CONNECTION ERRORS (identical to 1x)
90-99 - established connection errors