What is NAT (Network Address Translation)?

How NAT works

Devices inside a NAT-ed network use private addresses from reserved ranges such as 192.168.0.0/16 or 10.0.0.0/8, which are not routable on the public internet. When a device opens an outbound connection, the router rewrites the packet's source address to its own public address, picks a source port, and records the mapping in a translation table. Replies arriving on that port are rewritten back and delivered to the original device.

The dominant variant, NAPT (network address and port translation, often called PAT), multiplexes many internal devices through one public address by giving each connection its own port. Carrier-grade NAT (CGNAT) applies the same idea at ISP scale, placing hundreds or thousands of subscribers — the norm on mobile networks — behind each public IPv4 address.

NAT is stateful and outbound-oriented: connections initiated from inside work automatically, while unsolicited inbound connections are dropped unless port forwarding or traversal techniques such as STUN are used.

Why NAT matters for proxies and scraping

NAT breaks the assumption that one IP address equals one user. A rate limit or ban keyed to a single address behind CGNAT can affect a whole crowd of unrelated subscribers, so websites that block aggressively on carrier and consumer ranges risk significant collateral damage — and many therefore treat those ranges leniently.

This shared-address effect is why mobile IPs carry unusually high trust: a single 4G/5G exit address can legitimately represent thousands of subscribers, so blocking it outright is expensive for a website. Mobile proxies, such as ProxyOmega's Mobile plan with real 4G/5G carrier IPs, route traffic through exactly these high-trust shared addresses.

Practical notes and common misconceptions

NAT is not a proxy. It rewrites addresses at the network layer, transparently and without understanding the application protocol; it offers no authentication, no location choice, and no rotation logic. It is also not a deliberate security control, although hiding internal addresses does obscure network structure as a side effect.

Strict or symmetric NAT can interfere with protocols that need inbound or peer-to-peer flows, and translation tables have finite capacity — under heavy connection churn, mappings can be evicted, which shows up as dropped or reset connections rather than an obvious error.