IpVerify verifies the remote process's ip from the configuration file. IpVerify heavily uses in_addr structure internally. I would simply change it to in6_addr and map IPv4 address into IPv6. (so called V4MAPPED). It would make Condor slightly slower and use more memory. However, having two different code path for IPv4 and IPv6 does not seem nice. 4byte->16byte would not be much overhead and will make everything cleaner and easier. Also, I guess future IP address system will surely be super-set of current IPv6 as IPv6 is super-set of IPv4.
 
+V4MAPPED address works fine. One caveat is that the log will have IPv6-formatted IP address, e.g. ::ffff:127.0.0.1. If somebody do mind, it is possible to remove "::ffff".
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 {section: Ulrich Mystery}
 Ulrich's Userlevel IPv6 Programming Introductionn - http://people.redhat.com/drepper/userapi-ipv6.html