unique IDs for connections to ipsvd programs

I have a suggestion for another environment variable to be set by the ipsvd 
programs. How about generating a unique ID for each connection and passing 
this ID on to 'prog' via an environment variable and also writing the ID to 
the log?

This gives 'prog' the chance to connect whatever it is doing to the entry in 
{tcp,ssl,udp}svd's log. For example, if 'prog' is an SMTP server, it could 
put the unique ID in the Received: header of the mail (and refrain from 
putting the delivering host's IP address there, e.g., for the privacy of the 
sender; the admin can still find out the IP address by cross-referencing the 
header with the logs using the unique ID).

There exists libraries for generating unique IDs, e.g.:
http://www.ossp.org/pkg/lib/uuid/

Or would it be feasible if 'prog' generated the unique ID itself and wrote it 
to standard output (together with whatever information it wishes to have in 
the logs connected with the ID, e.g., the value of TCPREMOTEIP)? Is it 
guaranteed that such outputs from multiple concurrent instances of 'prog' 
will not interfere?

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