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nDPI/tests/cfgs/monitoring/result/telegram_videocall_2.pcapng.out
Adrian Pekar 5f312c0cd6
Fix JA4 fingerprinting (#2915) 
* Fix JA4 ALPN fingerprint to use first and last characters

According to the JA4 specification (line 2139), the ALPN field should
contain the first and last characters of the first ALPN extension value.

Currently, nDPI uses the first and second characters (alpn[0] and alpn[1]),
which produces incorrect fingerprints that don't match other JA4
implementations like Wireshark.

For example, with ALPN 'http/1.1':
- Current (incorrect): 'ht' (first + second char)
- Fixed (correct):     'h1' (first + last char)

This change ensures nDPI's JA4 implementation conforms to the official
specification and maintains interoperability with other JA4 tools.

Fixes: Incorrect JA4 ALPN fingerprint generation

* Fix JA4 ALPN implementation to correctly parse first ALPN protocol

The previous fix attempted to use strlen(ja->client.alpn)-1 but this was
insufficient because nDPI modifies the ALPN string by:
1. Adding null terminators that truncate the last character
2. Converting semicolons to dashes, affecting multi-protocol ALPNs

This complete fix:
- Adds alpn_original_last field to store the true last character
- Captures the last character of the FIRST ALPN protocol only (before ;/,)
- Preserves the original character before nDPI's string modifications

Now correctly implements JA4 spec: first + last characters of first ALPN protocol
Examples:
- ALPN 'h2;http/1.1' -> 'h2' (not 'h.' or 'h1')
- ALPN 'http/1.1' -> 'h1' (not 'ht' or 'h.')

Fixes: #2914

* Fix JA4 SNI detection to properly handle missing SNI extensions

Previously, nDPI incorrectly set JA4 SNI flag to 'd' (domain present) for
flows without any SNI extension. This was because the logic only checked
for NDPI_NUMERIC_IP_HOST risk (set when SNI contains IP) but didn't
distinguish between missing SNI and domain SNI.

Now properly detects:
- No SNI extension → 'i' flag
- SNI with IP address → 'i' flag
- SNI with domain → 'd' flag

This matches the JA4 specification.
2025-07-10 14:03:27 +02:00

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DPI Packets (UDP): 315 (39.38 pkts/flow)
Confidence DPI : 8 (flows)
Num dissector calls: 192 (24.00 diss/flow)
LRU cache ookla: 0/0/0 (insert/search/found)
LRU cache bittorrent: 0/0/0 (insert/search/found)
LRU cache stun: 17/18/0 (insert/search/found)
LRU cache tls_cert: 0/2/0 (insert/search/found)
LRU cache mining: 0/0/0 (insert/search/found)
LRU cache msteams: 0/0/0 (insert/search/found)
LRU cache fpc_dns: 0/0/0 (insert/search/found)
Automa host: 2/0 (search/found)
Automa domain: 2/0 (search/found)
Automa tls cert: 1/0 (search/found)
Automa risk mask: 1/0 (search/found)
Automa common alpns: 0/0 (search/found)
Patricia risk mask: 2/0 (search/found)
Patricia risk mask IPv6: 0/0 (search/found)
Patricia risk: 0/0 (search/found)
Patricia risk IPv6: 1/0 (search/found)
Patricia protocols: 8/6 (search/found)
Patricia protocols IPv6: 2/0 (search/found)
MDNS 2 194 2
STUN 8 560 2
TelegramVoip 305 130511 4
Acceptable 315 131265 8
VoIP 305 130511 4
Network 10 754 4
JA Host Stats:
IP Address # JA4C
1 192.168.12.67 1
1 UDP 192.168.12.67:39968 <-> 91.108.9.106:1400 [proto: 30.355/DTLS.TelegramVoip][IP: 185/Telegram][Stream Content: Audio, Video][Encrypted][Confidence: DPI][FPC: 78/STUN, Confidence: DPI][DPI packets: 244][DPI packets before monitoring: 43][cat: VoIP/10][124 pkts/50596 bytes <-> 120 pkts/70545 bytes][Goodput ratio: 90/93][2.48 sec][Hostname/SNI: telegram.org][bytes ratio: -0.165 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 0/0 19/20 633/629 67/66][Pkt Len c2s/s2c min/avg/max/stddev: 70/84 408/588 1253/1235 406/467][Mapped IP/Port: 93.35.170.144:39295, 91.108.9.106:37674, 91.108.9.106:52874][Peer IP/Port: 91.108.9.106:52874][Relayed IP/Port: 91.108.9.106:37674][RTP packets: 81/82][Risk: ** Self-signed Cert **** TLS Cert About To Expire **][Risk Score: 150][Risk Info: 17/Nov/2024 16:19:00 - 18/Dec/2024 16:19:00 / CN=WebRTC][DTLSv1.2][JA3S: 6431b01c80e20aa21a6d7a54b248a3bf][Issuer: CN=WebRTC][Subject: CN=WebRTC][Certificate SHA-1: 27:83:F6:62:B2:02:79:6C:C7:B9:73:6C:DA:79:A5:2F:71:48:C3:83][Validity: 2024-11-17 16:19:00 - 2024-12-18 16:19:00][Cipher: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256][PLAIN TEXT (1/talggGwr)][Plen Bins: 0,22,11,4,10,2,6,1,7,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,3,6,4,2,0,0,1,4,6,3,0,0,0,0,0,0,0,0,0,0]
2 UDP 192.168.12.67:44275 <-> 91.108.9.10:597 [proto: 30.355/DTLS.TelegramVoip][IP: 185/Telegram][Encrypted][Confidence: DPI][FPC: 185/Telegram, Confidence: DPI][DPI packets: 33][cat: VoIP/10][17 pkts/2958 bytes <-> 16 pkts/2740 bytes][Goodput ratio: 76/75][2.07 sec][bytes ratio: 0.038 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 1/0 85/139 514/688 135/213][Pkt Len c2s/s2c min/avg/max/stddev: 82/106 174/171 638/614 119/118][Mapped IP/Port: 91.108.9.10:597][DTLSv1.2][JA4: dd2i110700_c45550529adf_d9dd6182da81][PLAIN TEXT (OUePGE4)][Plen Bins: 0,6,42,39,3,3,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
3 UDP 192.168.12.67:42417 <-> 91.108.13.26:598 [proto: 78.355/STUN.TelegramVoip][IP: 185/Telegram][ClearText][Confidence: DPI][FPC: 185/Telegram, Confidence: DPI][DPI packets: 18][cat: VoIP/10][9 pkts/1266 bytes <-> 9 pkts/1154 bytes][Goodput ratio: 70/67][1.72 sec][bytes ratio: 0.046 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 51/42 198/214 514/512 144/169][Pkt Len c2s/s2c min/avg/max/stddev: 82/106 141/128 162/162 33/15][Mapped IP/Port: 91.108.13.26:598][PLAIN TEXT (03U/SsH)][Plen Bins: 0,11,50,38,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
4 UDP 192.168.12.67:46675 <-> 91.108.17.8:597 [proto: 78.355/STUN.TelegramVoip][IP: 185/Telegram][ClearText][Confidence: DPI][FPC: 185/Telegram, Confidence: DPI][DPI packets: 10][cat: VoIP/10][5 pkts/650 bytes <-> 5 pkts/602 bytes][Goodput ratio: 68/65][1.68 sec][bytes ratio: 0.038 (Mixed)][IAT c2s/s2c min/avg/max/stddev: 191/190 333/382 514/569 125/162][Pkt Len c2s/s2c min/avg/max/stddev: 82/106 130/120 162/130 39/12][Mapped IP/Port: 91.108.17.8:597][Plen Bins: 0,20,50,30,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
5 UDP 192.168.12.67:39329 -> 91.108.13.3:1400 [proto: 78/STUN][IP: 185/Telegram][ClearText][Confidence: DPI][FPC: 78/STUN, Confidence: DPI][DPI packets: 4][cat: Network/14][4 pkts/280 bytes -> 0 pkts/0 bytes][Goodput ratio: 40/0][1.75 sec][Risk: ** Unidirectional Traffic **][Risk Score: 10][Risk Info: No server to client traffic][Plen Bins: 100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
6 UDP 192.168.12.67:44679 -> 91.108.17.49:1400 [proto: 78/STUN][IP: 185/Telegram][ClearText][Confidence: DPI][FPC: 78/STUN, Confidence: DPI][DPI packets: 4][cat: Network/14][4 pkts/280 bytes -> 0 pkts/0 bytes][Goodput ratio: 40/0][1.75 sec][Risk: ** Unidirectional Traffic **][Risk Score: 10][Risk Info: No server to client traffic][PLAIN TEXT (sENzap5)][Plen Bins: 100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
7 UDP [fe80::76da:38ff:feed:5332]:5353 -> [ff02::fb]:5353 [proto: 8/MDNS][IP: 0/Unknown][ClearText][Confidence: DPI][FPC: 8/MDNS, Confidence: DPI][DPI packets: 1][cat: Network/14][1 pkts/107 bytes -> 0 pkts/0 bytes][Goodput ratio: 42/0][< 1 sec][Hostname/SNI: _ipps._tcp.local][_ipps._tcp.local][Plen Bins: 0,100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
8 UDP 192.168.12.1:5353 -> 224.0.0.251:5353 [proto: 8/MDNS][IP: 0/Unknown][ClearText][Confidence: DPI][FPC: 8/MDNS, Confidence: DPI][DPI packets: 1][cat: Network/14][1 pkts/87 bytes -> 0 pkts/0 bytes][Goodput ratio: 51/0][< 1 sec][Hostname/SNI: _ipps._tcp.local][_ipps._tcp.local][Plen Bins: 0,100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
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