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+<a id="pt-spec.txt-3.5"></a>
+
+# Pluggable Transport Client Per-Connection Arguments
+
+Certain PT transport protocols require that the client provides
+per-connection arguments when making outgoing connections.  On
+the server side, this is handled by the "ARGS" optional argument
+as part of the "SMETHOD" message.
+
+On the client side, arguments are passed via the authentication
+fields that are part of the SOCKS protocol.
+
+First the "`<Key>=<Value>`" formatted arguments MUST be escaped,
+such that all backslash, equal sign, and semicolon characters
+are escaped with a backslash.
+
+Second, all of the escaped are concatenated together.
+
+Example:
+
+shared-secret=rahasia;secrets-file=/tmp/blob
+
+Lastly the arguments are transmitted when making the outgoing
+connection using the authentication mechanism specific to the
+SOCKS protocol version.
+
+```text
+    - In the case of SOCKS 4, the concatenated argument list is
+      transmitted in the "USERID" field of the "CONNECT" request.
+
+    - In the case of SOCKS 5, the parent process must negotiate
+      "Username/Password" authentication [RFC1929], and transmit
+      the arguments encoded in the "UNAME" and "PASSWD" fields.
+```
+
+If the encoded argument list is less than 255 bytes in
+length, the "PLEN" field must be set to "1" and the "PASSWD"
+field must contain a single NUL character.