[2025-10-27 Mon 00:48] <- Dynamic port forwarding

The protocol is used for forwarding internet traffic, particularly TCP/IP via a proxy server. Version 5 later added support for ipv6 and UDP that also allows dns lookups.

The handshake works as follows:

• Client connects and sends a greeting, which includes a list of authentication methods.
• Server chooses a method.
• Client sends multiple messages now.
• Finally the regular connection requests occur:
  • One packet from client to server with the version, command code, destination port, destination IP, and the user ID string.
  • Server responds with version, reply code, destination port and IP, which the client should bind to if the command code was BIND.