4.15.1 Setting the proxy type

The ‘Proxy type’ radio buttons allow you to configure what type of proxy you want PuTTY to use for its network connections. The default setting is ‘None’; in this mode no proxy is used for any connection.

• Selecting ‘HTTP’ allows you to proxy your connections through a web server supporting the HTTP CONNECT command, as documented in RFC 2817.
• Selecting ‘SOCKS 4’ or ‘SOCKS 5’ allows you to proxy your connections through a SOCKS server.
• Many firewalls implement a less formal type of proxy in which a user can make a Telnet connection directly to the firewall machine and enter a command such as connect myhost.com 22 to connect through to an external host. Selecting ‘Telnet’ allows you to tell PuTTY to use this type of proxy.
• Selecting ‘Local’ allows you to specify an arbitrary command on the local machine to act as a proxy. When the session is started, instead of creating a TCP connection, PuTTY runs the command (specified in section 4.15.5), and uses its standard input and output streams.

  This could be used, for instance, to talk to some kind of network proxy that PuTTY does not natively support; or you could tunnel a connection over something other than TCP/IP entirely.

  If you want your local proxy command to make a secondary SSH connection to a proxy host and then tunnel the primary connection over that, you might well want the -nc command-line option in Plink. See section 3.8.3.14 for more information.

  You can also enable this mode on the command line; see section 3.8.3.24.