---
tags:
  - networking
---
A function in the kernel that allows guests with internal/private IPs to access the internet by using the hosts' public IP similar to 1 to many NAT.

Differences with Proxy, IP Masq, NAT:

**Proxy**
Requires special configuration on internal client side. Can be used for caching.

**IP Masq**
A form of NAT used primarily in Linux devices. Translates IP address and uses the connection tracking table and ports to map responses back to the internal connection.

**NAT**
Has different types with different use-cases.
Static NAT: 1-1 mapping of pub/private IP. Dynamic NAT: pool of pub ips to dynamically map private IPs to based on availability. 
PAT (Port): similar to IP Masq; 1-many using ports.