TCP SYN (p0f)

6:42+22:0:1440:mss*45,10:mss,sok,ts,nop,ws:flow:0

first seen 2026-07-01 17:44 · last seen 2026-08-27 21:08 · JSON

Distinct clients per day (last 30 days, peak 7/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 version6
Initial TTL42+22
Options length0
MSS1440
Window sizemss*45
Window scale10
Options layoutmss,sok,ts,nop,ws
Quirksflow
Payload class0

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)

fingerprintco-occurrences
t13d3112h1_1d947a95fc68_b72e173852fa73
t13d3112h1_1d947a95fc68_fa269c3d986d53
t13d1817h2_e8a523a41297_3cbfd9057e0d1
t13d1816h2_e8a523a41297_0c27189014cf1
t13d1713h1_ab0a1bf427ad_ecd0401ec68b Match?Exact match in Thumbprint's published controlled catalog captures: python-httpx 0.28.1.The fingerprint page shows the full measured match list. More on the catalog.1

HTTP request (JA4H)

fingerprintco-occurrences
ge11nn07cscz_62ad33df7c0a_000000000000_00000000000049
ge11nn07cscz_d4021d63333c_000000000000_00000000000032
ge11nn06cscz_fcadf6bdaa82_000000000000_00000000000018
ge11nn06cscz_a9e98b5c162a_000000000000_00000000000016
ge11nn06cscz_f604b96915d0_000000000000_00000000000011
ge20nr12en00_979a40433f82_000000000000_0000000000001
ge20nr14en00_cafa353882cc_000000000000_0000000000001
ge11nn05enus_f3bb7aa45ec4_000000000000_0000000000001

HTTP/2 frames (Akamai)

fingerprintco-occurrences
1:65536;2:0;4:131072;5:16384|12517377|3:0:0:22|m,p,a,s Match?Exact match in Thumbprint's published controlled catalog captures: firefox 153.0, firefox 153.0.3, firefox 154.0, +25 more.The fingerprint page shows the full measured match list. More on the catalog.2

TCP SYN (JA4T)

fingerprintco-occurrences
64800_2-4-8-1-3_1440_10129

User-Agent

fingerprintco-occurrences
Mozilla/5.0 (compatible; SeznamBot/4.0; +https://o-seznam.cz/napoveda/vyhledavani/en/seznambot-crawler/)126
Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.02
TechSpyBot/1.0 (+https://techspy.pro/bot)1

Country

fingerprintco-occurrences
CZ · Czechia126
FR · France2
FI · Finland1

Network (ASN)

fingerprintco-occurrences
AS43037 · Seznam.cz, a.s.126
AS12322 · Free SAS2
AS24940 · Hetzner Online GmbH1

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).

fingerprintlinked observations
q13d0314h3_55b375c5d22e_61e396c58b1f2