[Apparently the usenet gateway is not bidirectional, so I re-post here, sorry] Hello, AFAIK, there's nothing in the RADIUS protocol allowing you to ask a RADIUS server which user is currently using a given IP address... or am I missing something? The only thing you can do is FreeRADIUS-specific like issuing the "radwho" command which shows you a list of currently logged users, their IP addresses and other informations. Another option is querying the FreeRADIUS database (MySQL/whatever...), which is actually what some front-ends do (like DaloRADIUS...). Do you know a more robust/standard/portable solution to get these info? To clarify my question I will explain why I need this. I'm configuring DansGuardian web content filtering (http://dansguardian.org) which has the possibility to configure several "filter groups" each with different filtering rules. I would like to match filter groups by RADIUS login but since this is not implemented I'm willing to contribute some code to the project, and here I need to clarify some technical details. The programmatic counterpart of running radwho should be reading /var/log/freeradius/radutmp, which is simply the serialization of a C struct, as I read here: http://goo.gl/Rq1c7 http://goo.gl/BSvAn http://goo.gl/erLtw Would be this one the correct approach? Any suggestion? Thanks! Guido De Rosa P.S. the matching thread in the DG mailing list is: http://tech.groups.yahoo.com/group/dansguardian/message/24488