Difference between SNAT and Masquerade

Question

I am confused what's the actual difference between SNAT and Masquerade?

If I want to share my internet connection on local network than whether should I select SNAT or Masquerade?

Give me some online resources from where I can study about them. Thanks!

Also let me know the iptables command for both.

Answer 1

The SNAT target requires you to give it an IP address to apply to all the outgoing packets. The MASQUERADE target lets you give it an interface, and whatever address is on that interface is the address that is applied to all the outgoing packets. In addition, with SNAT, the kernel's connection tracking keeps track of all the connections when the interface is taken down and brought back up; the same is not true for the MASQUERADE target.

Good documents include the HOWTOs on the Netfilter site and the iptables man page.