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23 - Pentesting Telnet

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Basic Information

Telnet is a network protocol that gives users a UNsecure way to access a computer over a network.
Default port: 23
23/tcp open telnet

Enumeration

nc -vn <IP> 23
All the interesting enumeration can be performed by nmap:
nmap -n -sV -Pn --script "*telnet* and safe" -p 23 <IP>
The script telnet-ntlm-info.nse will obtain NTLM info (Windows versions).
In the TELNET Protocol are various "options" that will be sanctioned and may be used with the "DO, DON'T, WILL, WON'T" structure to allow a user and server to agree to use a more elaborate (or perhaps just different) set of conventions for their TELNET connection. Such options could include changing the character set, the echo mode, etc. (From the telnet RFC) I know it is possible to enumerate this options but I don't know how, so let me know if know how.

Config file

/etc/inetd.conf
/etc/xinetd.d/telnet
/etc/xinetd.d/stelnet

HackTricks Automatic Commands

Protocol_Name: Telnet #Protocol Abbreviation if there is one.
Port_Number: 23 #Comma separated if there is more than one.
Protocol_Description: Telnet #Protocol Abbreviation Spelled out
Entry_1:
Name: Notes
Description: Notes for t=Telnet
Note: |
wireshark to hear creds being passed
tcp.port == 23 and ip.addr != myip
https://book.hacktricks.xyz/pentesting/pentesting-telnet
Entry_2:
Name: Banner Grab
Description: Grab Telnet Banner
Command: nc -vn {IP} 23
Entry_3:
Name: Nmap with scripts
Description: Run nmap scripts for telnet
Command: nmap -n -sV -Pn --script "*telnet*" -p 23 {IP}
Entry_4:
Name: consoleless mfs enumeration
Description: Telnet enumeration without the need to run msfconsole
Note: sourced from https://github.com/carlospolop/legion
Command: msfconsole -q -x 'use auxiliary/scanner/telnet/telnet_version; set RHOSTS {IP}; set RPORT 23; run; exit' && msfconsole -q -x 'use auxiliary/scanner/telnet/brocade_enable_login; set RHOSTS {IP}; set RPORT 23; run; exit' && msfconsole -q -x 'use auxiliary/scanner/telnet/telnet_encrypt_overflow; set RHOSTS {IP}; set RPORT 23; run; exit' && msfconsole -q -x 'use auxiliary/scanner/telnet/telnet_ruggedcom; set RHOSTS {IP}; set RPORT 23; run; exit'
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