TCP SYN (p0f)

4:37+27:0:1412:mss*44,7:mss,sok,ts,nop,ws:df,id+:0

first seen 2026-06-19 09:11 · last seen 2026-07-25 12:57 · 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

4:37+27:0:1412:mss*44,7:mss,sok,ts,nop,ws:df,id+:0

Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWe…

User-Agent claims Windows

TCP SYN initial TTL 37+27 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 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.157 Safari/537.36
Observed TTL	37+27 (observed + path distance → initial)
Claimed OS	Windows
Confidence	low — single sighting of an environmental signal

low

2026-07-25

Decomposed attributes

IP version	`4`
Initial TTL	`37+27`
Options length	`0`
MSS	`1412`
Window size	`mss*44`
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
`t13d591000_a33745022dd6_1f22a2ca17c4`	2
`t13d1516h2_8daaf6152771_d8a2da3f94cd` Match?Exact match in Thumbprint's published controlled catalog captures: chromium 149.0.7827.102, chrome 149.0.7827.102, chrome 149.0.7827.156, +25 more.The fingerprint page shows the full measured match list. More on the catalog.	1
`t13d4412h1_fd39b124ee10_58ed7828516f`	1

HTTP request (JA4H)

fingerprint	co-occurrences
`ge11nn030000_341eb0d8946c_000000000000_000000000000`	2
`ge20nr13enus_54728652be35_000000000000_000000000000` Match?Exact match in Thumbprint's published controlled catalog captures: chromium 149.0.7827.102, chrome 149.0.7827.102, edge 149.0.4022.52, +10 more.The fingerprint page shows the full measured match list. More on the catalog.	1
`ge11nn050000_b223a0ebb0b5_000000000000_000000000000` Match?Exact match in Thumbprint's published controlled catalog captures: python-requests 2.34.2, python-requests 2.33.1, python-requests 2.32.3.The fingerprint page shows the full measured match list. More on the catalog.	1

HTTP/2 frames (Akamai)

fingerprint	co-occurrences
`1:65536;2:0;4:6291456;6:262144\|15663105\|1:1:0:220\|m,a,s,p` Match?Exact match in Thumbprint's published controlled catalog captures: chrome 150.0.7871.187, chromium 149.0.7827.102, chrome 149.0.7827.102, +59 more.The fingerprint page shows the full measured match list. More on the catalog.	1

TCP SYN (JA4T)

fingerprint	co-occurrences
`64240_2-4-8-1-3_1412_7`	1

User-Agent

fingerprint	co-occurrences
`axios/0.19.2`	2
`Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/146.0.0.0 Safari/537.36`	1
`Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.157 Safari/537.36`	1

Country

fingerprint	co-occurrences
`TH` · Thailand	3
`PK` · Pakistan	1

Network (ASN)

fingerprint	co-occurrences
`AS45758` · Triple T Broadband Public Company Limited	3
`AS9541` · Cyber Internet Services (Pvt) Ltd.	1

Cross-transport links

TLS ClientHello fingerprints observed from the same client via the beacon's correlation id on the other transport (e.g. this stack over TCP ↔ that stack over QUIC).

fingerprint	linked observations
`q13d0311h3_55b375c5d22e_653d80c3fe9d`	1