Dynamic port forwarding by means of a local SOCKS server. Fully

supports SOCKS 4, SOCKS 4A and SOCKS 5 (well, actually IPv6 in SOCKS
5 isn't supported, but it'll be no difficulty once I actually get
round to it). Thanks to Chas Honton for his `stone soup' patch: I
didn't end up actually using any of his code, but it galvanised me
into doing it properly myself :-)

[originally from svn r3055]

unix/uxplink.c

@@ -263,6 +263,7 @@ static void usage(void)
     printf("  -batch    disable all interactive prompts\n");
     printf("The following options only apply to SSH connections:\n");
     printf("  -pw passw login with specified password\n");
+    printf("  -D listen-port   Dynamic SOCKS-based port forwarding\n");
     printf("  -L listen-port:host:port   Forward local port to "
 	   "remote address\n");
     printf("  -R listen-port:host:port   Forward remote port to"