# Device Fingerprint

Detect your device's operating system through TCP/IP and UDP/IP network packet analysis. See how TTL, TCP options, and IP headers reveal your OS.

 

   

  Loading TCP fingerprint... 

 ### TCP Fingerprints

 

 JA4T Fingerprint Loading...  

 

 Satori Fingerprint Loading...  

 

 

 ### Compare My Fingerprint

 

See how your TCP/IP fingerprint matches against known OS profiles from our database.

 Analyzing fingerprint...

 



 

 ##### Unlock Real Fingerprint Analysis

Sign up for free to see how your actual TCP/IP fingerprint compares against our database of real device profiles.

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 ### IP Header

 

TTL

-

 

IP ID

-

 

TOS/DSCP

-

 

DF Flag

-

 

IP Version

-

 

Total Length

-

 

 

 ### TCP Header

 

Window Size

-

 

MSS

-

 

Window Scale

-

 

Flags

-

 

Options Order

-

 

TCP Options Detail

 Loading... 

 

 

 ### Estimated Network Properties

 

Initial TTL

-

 

Hops

-

 

Link Type

-

 

MTU

-

 

RTT

-

 

 

 

 

 

 

  Loading UDP/IP fingerprint via QUIC... 

 ### IP Header (from UDP packet)

 

TTL

-

 

IP ID

-

 

TOS

-

 

DF Flag

-

 

IP Version

-

 

 

 ### Estimated Network Properties

 

Initial TTL

-

 

Hops

-

 

Link Type

-

 

Estimated MTU

-

 

 

 

 

 

 

 

#####   

 

 TCP/IP fingerprinting (also known as OS fingerprinting or passive fingerprinting) identifies the operating system of a remote device by analyzing characteristics of network packets. Different operating systems implement the TCP/IP stack differently, leaving unique signatures in packet headers.

###### Key Fingerprinting Signals

###### IP Header Fields

- **TTL (Time To Live):** Linux/macOS use 64, Windows uses 128, Solaris uses 255
- **IP ID:** Randomization patterns vary by OS
- **DF Flag:** Don't Fragment behavior differs
- **TOS/DSCP:** Traffic class settings
 
 

###### TCP Header Fields

- **Window Size:** Initial window size varies by OS
- **TCP Options:** Order and presence of MSS, SACK, timestamps, window scaling
- **MSS:** Maximum Segment Size reveals MTU settings
- **Window Scale:** Scaling factor differs by OS version
 
 

 

###### TCP vs UDP Fingerprinting

 | Feature | TCP | UDP (QUIC) |
|---|---|---|
| Available Signals | IP + TCP options (MSS, WS, SACK, TS) | IP only (TTL, ID, TOS, DF) |
| Detection Accuracy | High (20+ signal points) | Lower (~4 signal points) |
| Use Case | HTTP/1.1, HTTP/2, HTTPS | HTTP/3, QUIC connections |

 

###### Privacy Implications

 TCP/IP fingerprinting can be used by websites and security systems to:

- Detect VPNs and proxies (TTL mismatches reveal extra network hops)
- Identify bot traffic (tools like curl have different fingerprints than browsers)
- Track users across sessions (fingerprint is consistent per device/OS)
- Detect OS spoofing attempts (User-Agent doesn't match TCP fingerprint)