# 123/udp - Pentesting NTP
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## Basic Information
The Network Time Protocol (**NTP**) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks.
**Default port:** 123/udp
```
PORT STATE SERVICE REASON
123/udp open ntp udp-response
```
## Enumeration
```bash
ntpq -c readlist
ntpq -c readvar
ntpq -c peers
ntpq -c associations
ntpdc -c monlist
ntpdc -c listpeers
ntpdc -c sysinfo
```
```bash
nmap -sU -sV --script "ntp* and (discovery or vuln) and not (dos or brute)" -p 123
```
## Examine configuration files
* ntp.conf
## NTP Amplification Attack
[**How NTP DDoS Attack Works**](https://resources.infosecinstitute.com/network-time-protocol-ntp-threats-countermeasures/#gref)
NTP protocol by design uses UDP to operate, which does not require any handshake like TCP, thus no record of the request. So, NTP DDoS amplification attack begins when an attacker crafts packets with a spoofed source IP to make the packets appear to be coming from the intended target and sends them to NTP server. Attacker initially crafts the packet of few bytes, but NTP responds with a large amount of data thus adding to amplification of this attack.
_MONLIST command_: It is a NTP protocol command which has very little use, but it is this command which is the main culprit for this attack. However, the use of MONLIST command is to give details of the last 600 clients that have connected to the NTP time service. Below is the command syntax:
```bash
ntpdc -n -c monlist
```
## Shodan
* `ntp`
## HackTricks Automatic Commands
```
Protocol_Name: NTP #Protocol Abbreviation if there is one.
Port_Number: 123 #Comma separated if there is more than one.
Protocol_Description: Network Time Protocol #Protocol Abbreviation Spelled out
Entry_1:
Name: Notes
Description: Notes for NTP
Note: |
The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks.
https://book.hacktricks.xyz/pentesting/pentesting-ntp
Entry_2:
Name: Nmap
Description: Enumerate NTP
Command: nmap -sU -sV --script "ntp* and (discovery or vuln) and not (dos or brute)" -p 123 {IP}
```
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