Similar to SNAT/DNAT depending on chain: it takes a range of addresses
(`--to 1.2.3.4-1.2.3.7') and gives a client the same
source-/destination-address for each connection.
.TP
\fB--to\fP \fIipaddr\fP[\fB-\fP\fIipaddr\fP]
Addresses to map source to. May be specified more than once for
multiple ranges.
.TP
.B "--nodst"
Don't use the destination-ip in the calculations when selecting the
new source-ip
.TP
.B "--random"
Port mapping will be forcibly randomized to avoid attacks based on 
port prediction (kernel >= 2.6.21).