Split the TOR_PT_OUTBOUND_BIND_ADDRESS into a V4/V6 variant.

         TOR_PT_EXIT_ON_STDIN_CLOSE=1

     "TOR_PT_OUTBOUND_BIND_ADDRESS"

     "TOR_PT_OUTBOUND_BIND_ADDRESS_V4"

       Specifies an IP address that the PT proxy SHOULD use as source address for

       outgoing IP packets. This feature allows people with multiple network

       interfaces to specify explicitly which interface they prefer the PT proxy to use.

       Specifies an IPv4 IP address that the PT proxy SHOULD use as source address for

       outgoing IPv4 IP packets. This feature allows people with multiple network

       interfaces to specify explicitly which interface they prefer the PT proxy to

       use.

       If this value is unset or empty, the PT proxy MUST use the default source

       address for outgoing connections.

       This setting MUST be ignored for connections to

       loopback addresses (127.0.0.0/8 and [::1]).

       loopback addresses (127.0.0.0/8).

       IPv6 addresses MUST always be wrapped in square brackets.

       Example:

         TOR_PT_OUTBOUND_BIND_ADDRESS_V4=203.0.113.4

     "TOR_PT_OUTBOUND_BIND_ADDRESS_V6"

       Specifies an IPv6 IP address that the PT proxy SHOULD use as source address for

       outgoing IPv6 IP packets. This feature allows people with multiple network

       interfaces to specify explicitly which interface they prefer the PT proxy to

       use.

       Example with IPv4:

       If this value is unset or empty, the PT proxy MUST use the default source

       address for outgoing connections.

         TOR_PT_OUTBOUND_BIND_ADDRESS=203.0.113.4

       This setting MUST be ignored for connections to

       loopback addresses ([::1]).

       IPv6 addresses MUST always be wrapped in square brackets.

       Example with IPv6:

       Example::

         TOR_PT_OUTBOUND_BIND_ADDRESS=[2001:db8::4]

         TOR_PT_OUTBOUND_BIND_ADDRESS_V6=[2001:db8::4]

3.2.2. Pluggable Transport Client Environment Variables