TCP SYN (p0f)

4:40+24:0:1380:mss*47,10:mss,sok,ts,nop,ws:df,id+:0

first seen 2026-10-05 18:48 · last seen 2026-10-20 10:14 · JSON

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 version4
Initial TTL40+24
Options length0
MSS1380
Window sizemss*47
Window scale10
Options layoutmss,sok,ts,nop,ws
Quirksdf,id+
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
t13d1517h2_8daaf6152771_6f4c3a25c80122
t13d3013h1_1d37bd780c83_8537cf56674e9
t13d1516h2_8daaf6152771_14f25f0c9e964

HTTP request (JA4H)

fingerprintco-occurrences
ge20nr13enus_52a9a314672a_000000000000_00000000000019
ge11nn040000_5d05004232a2_000000000000_0000000000009
ge20nr11enus_187a9385d229_000000000000_0000000000004
ge20nr12enus_a72b71f519fc_000000000000_0000000000001
ge20nr13enus_44e1f6d71293_000000000000_0000000000001
ge20nr15enus_88efceda7332_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 155.0.1, +31 more.The fingerprint page shows the full measured match list. More on the catalog.5
1:65536;2:0;4:131072;5:16384|12517377|3:0:0:42|m,p,a,s Match?Exact match in Thumbprint's published controlled catalog captures: firefox 154.0, firefox 152.0.5, firefox 152.0.1, +3 more.The fingerprint page shows the full measured match list. More on the catalog.3
1:65536;2:0;4:131072;5:16384|12517377|9:0:0:42|m,p,a,s1
1:65536;2:0;4:131072;5:16384|12517377|17:0:0:42|m,p,a,s1
1:65536;2:0;4:131072;5:16384|12517377|11:0:0:42|m,p,a,s1
1:65536;2:0;4:131072;5:16384|12517377|13:0:0:42|m,p,a,s1
1:65536;2:0;4:131072;5:16384|12517377|15:0:0:42|m,p,a,s1
1:65536;2:0;4:131072;5:16384|12517377|19:0:0:42|m,p,a,s1
1:65536;2:0;4:131072;5:16384|12517377|25:0:0:42|m,p,a,s1
1:65536;2:0;4:131072;5:16384|12517377|27:0:0:42|m,p,a,s1

TCP SYN (JA4T)

fingerprintco-occurrences
64860_2-4-8-1-3_1380_1035

User-Agent

fingerprintco-occurrences
Mozilla/5.0 (X11; Linux x86_64; rv:157.0) Gecko/20100101 Firefox/157.025
curl/8.22.09
Mozilla/5.0 (X11; Linux x86_64; rv:158.0) Gecko/20100101 Firefox/158.01

Country

fingerprintco-occurrences
PL · Poland35

Network (ASN)

fingerprintco-occurrences
AS16276 · OVH SAS35

TLS supported groups

fingerprintco-occurrences
11ec,001d,0017,0018,0019,02021

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
q13d0315h3_55b375c5d22e_bb76f32061e35