TCP SYN (p0f)

4:45+19:0:1380:mss*20,7:mss,sok,ts,nop,ws:df,id+:0

first seen 2026-06-14 23:29 · last seen 2026-06-14 23:29 · JSON

Inconsistencies

User-Agents observed with this fingerprint that contradict what it proves at the wire. all inconsistencies →

fingerprint User-Agent claims wire shows confidence seen first seen last seen

4:45+19:0:1380:mss*20,7:mss,sok,ts,nop,ws:df,id+:0

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.…

User-Agent claims Windows

TCP SYN initial TTL 45+19 indicates Unix-like

The initial TTL is set by the sending kernel (64 on Unix-like systems, 128 on Windows) and survives NAT. But VPNs, proxies and tunnels legitimately replace the sending stack, so this check never exceeds medium confidence.

Full User-Agent	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0
Observed TTL	45+19 (observed + path distance → initial)
Claimed OS	Windows
Confidence	low — single sighting of an environmental signal

low

2026-06-14

Decomposed attributes

IP version	`4`
Initial TTL	`45+19`
Options length	`0`
MSS	`1380`
Window size	`mss*20`
Window scale	`7`
Options layout	`mss,sok,ts,nop,ws`
Quirks	`df,id+`
Payload class	`0`

Co-observed signals

Signals from other families seen in the same observation. A fingerprint spread thinly across many lower-layer signatures is a classic inconsistency signal.

TLS ClientHello (JA4)

fingerprint	co-occurrences
`t12d860700_e18388e7f3a3_4446390ac224`	1

HTTP request (JA4H)

fingerprint	co-occurrences
`ge11nn030000_6f76d0e5ec76_000000000000_000000000000`	1

User-Agent

fingerprint	co-occurrences
`Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0`	1

Country

fingerprint	co-occurrences
`US` · United States	1

Network (ASN)

fingerprint	co-occurrences
`AS16417` · Cisco Systems Ironport Division	1