I don't know any of those download managers, the only one download manager I know is ftp, and that is blocked by this pf.conf
So it is time to print out and study the
pf.conf man page. The following should give you a start.
Code:
For stateful TCP connections, limits on established connections (connec-
tions which have completed the TCP 3-way handshake) can also be enforced
per source IP.
max-src-conn <number>
Limits the maximum number of simultaneous TCP connections which
have completed the 3-way handshake that a single host can make.
max-src-conn-rate <number> / <seconds>
Limit the rate of new connections over a time interval. The con-
nection rate is an approximation calculated as a moving average.
Because the 3-way handshake ensures that the source address is not being
spoofed, more aggressive action can be taken based on these limits. With
the overload <table> state option, source IP addresses which hit either
of the limits on established connections will be added to the named
table. This table can be used in the ruleset to block further activity
from the offending host, redirect it to a tarpit process, or restrict its
bandwidth.