TCP SYN (p0f)

4:84+?:0:1380:65535,8:mss,sok,ts,nop,ws:df,id+:0

first seen 2026-08-08 19:13 · last seen 2026-09-07 23:57 · 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

4:84+?:0:1380:65535,8:mss,sok,ts,nop,ws:df,id+:0

Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) …

User-Agent claims macOS

TCP SYN initial TTL 84+? indicates Windows

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 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36 (compatible; meta-externalagent/1.1 (+https://developers.facebook.com/docs/sharing/webmasters/crawler))
Observed TTL	84+? (observed + path distance → initial)
Claimed OS	macOS
Confidence	medium — repeated co-occurrence, but initial TTL is environmental — capped at medium

medium

2026-08-12

2026-08-15

Distinct clients per day (last 30 days, peak 2/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	`84+?`
Options length	`0`
MSS	`1380`
Window size	`65535`
Window scale	`8`
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
`t13d3111h2_e8f1e7e78f70_5ac7197df9d2`	16

HTTP request (JA4H)

fingerprint	co-occurrences
`ge20nn030000_80b089f68b8e_000000000000_000000000000`	11
`ge20nn09enus_c5abe4666a67_000000000000_000000000000`	3
`ge20nn070000_1903711a2262_000000000000_000000000000`	2

HTTP/2 frames (Akamai)

fingerprint	co-occurrences
`1:4096;2:0;5:16384;6:131072;3:100;4:65536\|26148865\|0\|m,s,p,a`	14
`1:4096;2:0;5:16384;6:131072;3:100;4:65536;11105:65535;11106:65535;11107:65535;11108:10;11109:10\|26148865\|0\|m,s,p,a`	2

TCP SYN (JA4T)

fingerprint	co-occurrences
`65535_2-4-8-1-3_1380_8`	16

User-Agent

fingerprint	co-occurrences
`facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)`	6
`Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36 (compatible; meta-externalagent/1.1 (+https://developers.facebook.com/docs/sharing/webmasters/crawler))`	5
`Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36 (compatible; meta-externalagent/1.1 (+https://developers.facebook.com/docs/sharing/webmasters/crawler))`	4
`Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36 Edg/145.0.0.0 (compatible; meta-externalagent/1.1 (+https://developers.facebook.com/docs/sharing/webmasters/crawler))`	1

Country

fingerprint	co-occurrences
`US` · United States	11
`SG` · Singapore	5

Network (ASN)

fingerprint	co-occurrences
`AS32934` · Facebook, Inc.	16