Application Protocol Multiplexer

Crate 🦀

The Application Protocol Multiplexer is a tool that allows you to forward TCP or UDP traffic to different addresses based on regex pattern matching in the first packet sent by the client.

Usage

You can build this tool from source with cargo install portForwarder or download the prebuilt binary called portfd from the release page.

To run portfd with simple command line arguments, use the following syntax: portfd <local-bind> <remote>. In this case, you need to specify the listening address and the remote address. For more advanced usage, portfd can be started with a configuration file that supports more complex rules. Here's an example of a config file in YAML format:

forwarders:
  - local: 0.0.0.0:8808
    # Specify either 'remoteMap' or 'remote'
    remoteMap:
      - pattern: "[http:localhost]"
        remote: 192.168.44.43:5445
      - pattern: "[https:baidu.com]"
        remote: "39.156.66.10:443"
      - pattern: "[ssh]"
        remote: "192.168.44.43:22"
      - pattern: "[socks5]"
        remote: "192.168.100.46:7890"
      - pattern: "[rdp]"
        remote: 192.168.100.46:3389
      - pattern: .*
        remote: 192.168.100.46:23
    remote: <remote-address/127.0.0.1:2233>
    enable_tcp: true # Default is true
    enable_udp: true # Default is true
    conn_bufsize: 2MB
    max_connections: 10000 # Optional
    allow_nets: # Optional whitelist
      - 127.0.0.0/24

The pattern field supports six formats, all of which will be converted to regular expressions:

• [http] or [http:domain_name]: Only HTTP traffic or host names of HTTP requests matching domain_name will be forwarded to the specified remote address.
• [https:domain_name]: Matches the SNI (Server Name Indication) in the client hello for HTTPS traffic.
• [ssh]: Only SSH traffic will be forwarded.
• [socks5]: Only socks5 traffic will be forwarded.
• [rdp]: Only rdp traffic will be forwarded.
• any regex: Only the traffic of the first received packet that matches this regex will be forwarded.