Tool for quick testing of NTS (Network Time Security) servers.
Windows(tm) 7+ x64 command-line (CLI) tool for testing and diagnosing NTP servers that implement the KE (Key Establishment) protocol of the Network Time Security (NTS) authentication mechanism.
CLI: MS Windows(tm) x64 platform (7+, 2008+)
GUI: MS Windows(tm) x64 platform (10+, 2019+)
Usage: nts-tester.exe [OPTIONS] --server <SERVER>
Options:
-s, --server <SERVER> NTS-KE server hostname
-p, --ke-port <KE_PORT> NTS-KE TCP port [default: 4460]
--ntp-port <NTP_PORT> NTP UDP port override (default: 123 or from NTS-KE negotiation)
--ntp-server <NTP_SERVER> NTP server address override (default: same as NTS-KE server or from negotiation)
-n, --count <COUNT> Number of NTP queries to perform after NTS-KE [default: 1]
--placeholders <PLACEHOLDERS> Number of cookie placeholders per NTP request (0-7, default: auto)
-t, --timeout <TIMEOUT> Connection timeout in milliseconds [default: 5000]
--ke-only NTS-KE only (skip NTP queries)
-o, --output <OUTPUT> Output format [default: text] [possible values: text, json]
-v, --verbose Verbose output (show hex dumps, timing details)
--dump Hex-dump outgoing NTP packets before sending
--insecure Skip TLS certificate verification (DANGEROUS — for testing only)
--native-certs Use the OS native certificate store in addition to bundled root certificates
-h, --help Print help
-V, --version Print version
$nts-tester.exe --server nts1.ntp.hr
=== NTS-KE Handshake ===
Server: nts1.ntp.hr:4460
TLS Version: TLSv1_3
Cipher: TLS13_AES_256_GCM_SHA384
ALPN: ntske/1
Certificate:
Subject: CN=nts1.ntp.hr
Issuer: C=GB, O=Sectigo Limited, CN=Sectigo Public Server Authentication CA DV R36
Valid: Mar 18 00:00:00 2026 +00:00 to Oct 2 23:59:59 2026 +00:00
SANs: nts1.ntp.hr, www.nts1.ntp.hr
Protocol: NTPv4 (0x0000)
AEAD: AES-SIV-CMAC-256 (15)
Cookies: 8 received (104 bytes each)
Server Neg: (none)
Port Neg: (none)
Time: 529.5ms
NTP Target: nts1.ntp.hr:123 → 161.53.78.69:123
=== NTP Query 1/1 ===
Server: nts1.ntp.hr:123 (161.53.78.69:123)
T1 (Origin): 2026-03-20T13:07:09.939933Z [3983000829.4036982783]
T2 (Receive): 2026-03-20T13:07:09.250688Z [3983000829.1076699274]
T3 (Transmit): 2026-03-20T13:07:09.251004Z [3983000829.1078055289]
T4 (Dest): 2026-03-20T13:07:10.000904Z [3983000830.3884797]
Offset: -719.573ms
Delay: 60.656ms
Stratum: 1
Precision: -21 (476.8ns)
Root Delay: 0.000ms
Root Disp: 0.229ms
Ref ID: MRS
Cookies: 1 refreshed (8 available)
AEAD: OK (decryption verified)
Time: 60.6ms
Marko Jurcevic | contact:ntstimetools@crobiz.com | Vesco informatika d.o.o. | Zagreb | Croatia
End User License Agreement
Introduction
This End-User License Agreement ("EULA") is a legal agreement between you (either an individual or a single entity) and Vesco informatika d.o.o. ("Licensor") for the use of NTS Time Tools (NTS Tester in CLI and GUI version, NTS TimeSync) ("Software"). This EULA governs your use of the Software provided by the Licensor. By clicking "I Agree" or installing or using the Software, you agree to be bound by the terms of this EULA.
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NTS Time Tools - Vesco informatika d.o.o.