1 This target is only valid in the 2 .B nat 3 table, in the 4 .B POSTROUTING 5 and 6 .B INPUT 7 chains, and user-defined chains which are only called from those 8 chains. It specifies that the source address of the packet should be 9 modified (and all future packets in this connection will also be 10 mangled), and rules should cease being examined. It takes the 11 following options: 12 .TP 13 \fB\-\-to\-source\fP [\fIipaddr\fP[\fB\-\fP\fIipaddr\fP]][\fB:\fP\fIport\fP[\fB\-\fP\fIport\fP]] 14 which can specify a single new source IP address, an inclusive range 15 of IP addresses. Optionally a port range, 16 if the rule also specifies one of the following protocols: 17 \fBtcp\fP, \fBudp\fP, \fBdccp\fP or \fBsctp\fP. 18 If no port range is specified, then source ports below 512 will be 19 mapped to other ports below 512: those between 512 and 1023 inclusive 20 will be mapped to ports below 1024, and other ports will be mapped to 21 1024 or above. Where possible, no port alteration will occur. 22 In Kernels up to 2.6.10, you can add several \-\-to\-source options. For those 23 kernels, if you specify more than one source address, either via an address 24 range or multiple \-\-to\-source options, a simple round-robin (one after another 25 in cycle) takes place between these addresses. 26 Later Kernels (>= 2.6.11-rc1) don't have the ability to NAT to multiple ranges 27 anymore. 28 .TP 29 \fB\-\-random\fP 30 If option 31 \fB\-\-random\fP 32 is used then port mapping will be randomized through a hash-based algorithm (kernel >= 2.6.21). 33 .TP 34 \fB\-\-random-fully\fP 35 If option 36 \fB\-\-random-fully\fP 37 is used then port mapping will be fully randomized through a PRNG (kernel >= 3.14). 38 .TP 39 \fB\-\-persistent\fP 40 Gives a client the same source-/destination-address for each connection. 41 This supersedes the SAME target. Support for persistent mappings is available 42 from 2.6.29-rc2. 43 .PP 44 Kernels prior to 2.6.36-rc1 don't have the ability to 45 .B SNAT 46 in the 47 .B INPUT 48 chain. 49 .TP 50 IPv6 support available since Linux kernels >= 3.7. 51
