If no port range is specified, then source ports below 512 will be
mapped to other ports below 512: those between 512 and 1023 inclusive
will be mapped to ports below 1024, and other ports will be mapped to
-1024 or above. Where possible, no port alteration will occur.
-.RS
-.PP
+1024 or above. Where possible, no port alteration will
+
In Kernels up to 2.6.10, you can add several --to-source options. For those
kernels, if you specify more than one source address, either via an address
range or multiple --to-source options, a simple round-robin (one after another
in cycle) takes place between these addresses.
Later Kernels (>= 2.6.11-rc1) don't have the ability to NAT to multiple ranges
anymore.
+.TP
+.BR "--random"
+If option
+.B "--random"
+is used then port mapping will be randomized (kernel >= 2.6.21).
+.RS
+.PP