// REFERENCE
Port 23 (Telnet)
Protocol: TCP
Service: Telnet
High risk
Telnet: a remote shell with no encryption. Everything (including the password) travels in the clear. It should never be open; use SSH (22). Seeing it open often flags legacy IoT or network gear.
Related tools
Work with this in:
Related
22
Port 22 (SSH) 1194
Port 1194 (OpenVPN) 1723
Port 1723 (PPTP VPN) 2222
Port 2222 (alternate SSH) 3389
Port 3389 (RDP) 5900
Port 5900 (VNC)
Port 22 (SSH) 1194
Port 1194 (OpenVPN) 1723
Port 1723 (PPTP VPN) 2222
Port 2222 (alternate SSH) 3389
Port 3389 (RDP) 5900
Port 5900 (VNC)
Assignments per the IANA port registry. Educational content.