"-""+_L%C - %U [%d/%o/%Y:%H:%M:%S %z] ""%T"" 200 %I"

Redirections are usefull to e.g. forward requests from specific clients to different servers or proxy server. Additionally, redirections are usefull to convert proxy interface from ont format to another, e.g. requests from SOCKS proxy can be redirected to parent HTTP proxy, or SOCKSv5 client can be redirected to SOCKSv4 proxy.
Because 3proxy understand "transparent" web request, it can be used as an intermediate software between HTTP proxy and NAT server for transparent HTTP forwarding, because it can convert "Web server" request issued by client to "proxy request" required by proxy server. A simplest redirection is:

auth iponly
allow *
parent 1000 http 192.168.1.1 3128
proxy

auth iponly
allow * * * 80
parent 1000 http 0.0.0.0 0
allow * * * 21
parent 1000 ftp 0.0.0.0 0
allow * * * 110
parent 1000 pop3 0.0.0.0 0
socks

Proxy itself doesn't manage network level routing. The only way to control outgoing channel is to select external interface. It's possible to make external interface (what is usually selected with 'external' command or '-e' option) random by using local redirection with external port 0.

auth iponly
allow *
parent 500 http 10.1.1.101 0
parent 500 http 10.2.1.102 0

If both interface addresses are in same network, e.g. 10.1.1.101 and 10.1.1.102 and you want to select random gateway between 10.1.1.1 and 10.1.1.2, you must control it by using routing table, in case there is no default gateway route for Windows:

 route add -p 10.1.1.1 10.1.1.101
 route add -p 10.1.1.2 10.1.1.102
 route add -p 0.0.0.0 mask 0.0.0.0 192.168.1.1
 route add -p 0.0.0.0 mask 0.0.0.0 192.168.1.2

parent command may also be used to build a proxy chains. In this case few 'parent' commands are used for single 'allow' rule with different weights (first argument of parent command). Chain may contain any number of proxy servers, but it should be noted that every hope significantly reduces productivity. It's possible to mix different types of proxy within single chain: HTTPS (HTTP connect), SOCKS4, SOCKS5. Weight different from 1000 is used to build random chains. if weight W is below 1000, this proxy will be used as a next chain hop with probability of W/1000. That is, if the weight is 250 probability this proxy will be used for the next hope is 25%. 'parent' records with common weight of 1000 establish a group, one of these record will be used for the hop with probability according to weight. Warning: each group must have a weight even of 1000. As follows, common weight of all 'parent' records must also be even of 1000. If common weight of 'parent' records in te chain is 3000, chain has 3 hops and must be formed of 3 groups. Example:

allow *
parent 500 socks5 192.168.1.1 1080
parent 500 connect 192.168.10.1 3128

allow * * * 80
parent 1000 socks5 192.168.10.1 1080
parent 1000 connect 192.168.20.1 3128
parent 300 socks4 192.168.30.1 1080
parent 700 socks5 192.168.40.1 1080

3proxy supports bandwidth filters. To manage filters bandlimin/bandlimout and nobandlimin/nobandlimout. 'in' means incoming and 'out' - outgoing traffic.

bandlimin <bitrate> <userlist> <sourcelist> <targetlist> <targetportlist> <commandlist>
nobandlimin <userlist> <sourcelist> <targetlist> <targetportlist> <commandlist>

  bandlimin 57600 * 192.168.10.16
  bandlimin 57600 * 192.168.10.17
  bandlimin 57600 * 192.168.10.18
  bandlimin 57600 * 192.168.10.19

  bandlimin 57600 * 192.168.10.16/30

  nobandlimin * * * 110
  bandlimin 57600 * 192.168.10.16/32

counter <filename> <type> <reportpath>
countin <number> <type> <amount> <userlist> <sourcelist> <targetlist> <targetportlist> <commandlist>
nocountin <userlist> <sourcelist> <targetlist> <targetportlist> <commandlist>
countout <number> <type> <amount> <userlist> <sourcelist> <targetlist> <targetportlist> <commandlist>
nocountout <userlist> <sourcelist> <targetlist> <targetportlist> <commandlist>

You can set traffic limit per day (D), week (W), month (M), year (Y) or absolute ('N'), as specified by 'type' argument of counterin command. Traffic information is stored in binary file specified by 'filename' argument. countersutil utility can be used to manage this file. reportpath specifies location of text reports, type parameter of 'counter' command controls how often text reports are created. amount is amount of allowed traffic in Megabytes (MB). nocountin allows you to set exclusions.

Networks or users lists are often very huge. 3proxy doesn't currently supports user groups, but ones can be created by the means of include files. You can store comma-delimited lists of networks or users in the separate file and use $ macro to insert this list into 3proxy.cfg. 3proxy comes with 'dighosts' utility. This utility helps to grab the list of the network from HTTP page. It may be usefull to e.g. obtain a regullary updated list of local networks from ISP's server. A network list can be either in form of NETWORK MASK, e.g. 192.168.1.0 255.255.255.0 or NETWORK/LENGTH, e.g. 192.168.1.0/24. You can launch dighosts from 3proxy.cfg to be executed on every 3proxy startup or configuration reload:

system "dighosts http://provider/network.html local.networks"
allow * * $local.networks
allow *
parent 1000 proxy.provider 3128 *
proxy
flush

For name resolution and caching use commands nserver, nscache / nscache6 and nsrecord.

  nserver 192.168.1.2
  nserver 192.168.1.3:5353/tcp

  nscache 65535
  nscache6 65535

  nsrecord server.mycompany.example.com 192.168.1.1
  nsrecord www.porno.com 127.0.0.2
  ...
  deny * * 127.0.0.2

IPv6 is supported since 0.8. Please note, some proxy protolos, e.g. SOCKSv4, do not support IPv6. SOCKSv5 supports IPv6 with special request type (must be implemented by client).
3proxy supports proxying from IPv4 and IPv6 networks to IPv4, IPv6 and mixed networks. IPv6 address may be used in internal, external, parent commands, ACLs, -i and -e options,etc. external command and -e options may be given twice for each service - once with IPv4 and once with IPv6 address. internal can be given only once, to bind to all IPv4 and IPv6 addresses use [0:0:0:0:0:0:0:0] or [::].
Any service may be configured with -4, -46, -64, -6 options to specify decied priority for name to IPv4/IPv6 address resolution (IPv4 only, IPv4 priority, IPv6 priority, IPv6 only).

In example, users needs access from external network to proxy server located on the host 192.168.1.2. This host can not be accessed from external network, but it has access to external network with with external address 1.1.1.1. Also, user has access to the host 2.2.2.2 (IP address may be dynamic) with hostname host.dyndns.example.org via external network. User needs 2 instances of 3proxy, first one on the host 192.168.1.2 with config

  users user:CL:password
  auth strong
  allow user
  proxy -rhost.dyndns.example.org:1234

  auth iponly
  allow * * 1.1.1.1
  tcppm -R0.0.0.0:1234 3128 1.1.1.1 3128