TCP SYN (p0f)

4:43+21:0:1350:65535,6:mss,sok,ts,nop,ws:df,id+:0

first seen 2026-07-23 03:46 · last seen 2026-09-05 04:01 · 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

4:43+21:0:1350:65535,6: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 43+21 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/83.0.4103.116 Safari/537.36
Observed TTL	43+21 (observed + path distance → initial)
Claimed OS	Windows
Confidence	low — single sighting of an environmental signal

low

2026-07-26

4:43+21:0:1350:65535,6:mss,sok,ts,nop,ws:df,id+:0

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleW…

User-Agent claims Windows

TCP SYN initial TTL 43+21 indicates Unix-like

Full User-Agent	Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4950.0 Iron Safari/537.36
Observed TTL	43+21 (observed + path distance → initial)
Claimed OS	Windows
Confidence	low — single sighting of an environmental signal

low

2026-07-23

Distinct clients per day (last 30 days, peak 1/day)

Distinct clients are counted by IP-hash per complete UTC day — unlike observation counts this is insensitive to one chatty client, but NAT merges clients and address rotation splits them.

Decomposed attributes

IP version	`4`
Initial TTL	`43+21`
Options length	`0`
MSS	`1350`
Window size	`65535`
Window scale	`6`
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
`t13d4412h1_fd39b124ee10_58ed7828516f`	3
`t13d1515h1_8daaf6152771_0a20fe35d3a5`	1
`t13d1516h1_8daaf6152771_1a63afa7c478`	1

HTTP request (JA4H)

fingerprint	co-occurrences
`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.	3
`ge11nn13enus_9db22d02e17a_000000000000_000000000000`	2

TCP SYN (JA4T)

fingerprint	co-occurrences
`65535_2-4-8-1-3_1350_6`	5

User-Agent

fingerprint	co-occurrences
`Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36`	1
`Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36`	1
`Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.116 Safari/537.36`	1
`Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Brave Chrome/80.0.3987.162 Safari/537.36`	1
`Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4950.0 Iron Safari/537.36`	1

Country

fingerprint	co-occurrences
`VN` · Vietnam	3
`ZA` · South Africa	1
`BD` · Bangladesh	1

Network (ASN)

fingerprint	co-occurrences
`AS45899` · VNPT Corp	3
`AS29975` · Vodacom	1
`AS23688` · Link3 Technologies Ltd.	1