Class [ "name" limit|regex|ip value]
1.2.0pre9 and later
Controls class based access. Class base access allows each connecting IP to be classified into a separate class. Each class has its own maximum number of connections. limit sets the maximum number of connections (default is 100) for that class name, regex sets a hostname regex (POSIX) for inclusion in the class and ip sets an IP/netmask based inclusion.
Class local limit 100
Class default limit 10
Class local regex .*foo.com
Class local ip 172.16.1.0/24
This creates two classes, local and default, with local being everything in *.foo.com and 172.16.1.* combined.