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network/telnet.md

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+---
+title: "Telnet"
+description: "Enumeration, exploitation and post-exploitation techniques for Telnet servers."
+tags: ["telnet", "network", "service"]
+publishDate: 2026-05-04
+---
+
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+
+- [Enumeration](#enumeration)
+  - [Banner grabbing](#banner-grabbing)
+  - [Nmap](#nmap)
+- [Connect](#connect)
+- [Brute Force](#brute-force)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+
+Telnet runs on **port 23** and transmits all data (including credentials) in **cleartext**.
+Common on embedded devices, legacy systems, routers, and IoT equipment.
+
+## Enumeration
+
+### Banner grabbing
+
+```bash
+nc -nv $IP 23
+telnet $IP
+```
+
+The banner often reveals the OS, hostname, or device type.
+
+### Nmap
+
+```bash
+nmap -sV -p 23 $IP
+nmap -p 23 --script telnet-* $IP
+```
+
+Key scripts:
+
+- `telnet-ntlm-info`: extracts NTLM info (Windows targets)
+- `telnet-brute`: brute-force credentials
+
+## Connect
+
+```bash
+telnet $IP
+telnet $IP 23
+```
+
+Login with `user` / `password`. Session is fully interactive once authenticated.
+
+## Brute Force
+
+```bash
+hydra -l $user -P ~/wordlists/rockyou.txt telnet://$IP
+medusa -h $IP -u $user -P ~/wordlists/rockyou.txt -M telnet
+```
+
+Try default credentials first. Routers and embedded devices commonly ship with `admin:admin`, `root:root`, or blank passwords.