2026-03-04
TTL (Time To Live) — is an eight-bit field in the IP header that defines the maximum number of “hops” (nodes) a packet can traverse before being discarded. Each time it passes through any router the TTL value is decreased by 1.
Typical default TTL values
Different operating systems use different initial values. This allows remote OS fingerprinting.
| Operating system | Default TTL |
|---|---|
| Windows (all versions) | 128 |
| Linux (Ubuntu, Debian, CentOS, etc.) | 64 |
| Android | 64 |
| iOS / macOS | 64 |
| FreeBSD / Solaris | 255 |
Why change TTL? Usage patterns
1. Bypassing tethering restrictions (internet sharing)
The most common scenario. Mobile carriers analyze incoming traffic.
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