Telnet
Telnet is used to establish terminal connections to other computers. Telnet enables you to log on to another computer. Telnet sends all traffic, including passwords, unencrypted, which means that anybody who can access the cables between the two computers can eavesdrop on the communication. Therefore, it is not advisable to allow telnet to the internal network of your organization from an insecure network such as Internet. We recommend only allowing telnet on networks that you control, and maybe from your network out to the insecure network.
Telnet usually uses a high port on the client, port 23 on the server and the TCP protocol.
This corresponds to the following service definition:
| Services | ||||
|---|---|---|---|---|
| Name | Protocol | Firewall type | Client ports | Server ports |
| telnet | TCP | Dynamic session management | 1024-65535 | 23 |
See the SMTP or HTTP section for information on how to create firewall rules and relays.