Conclusion

TELNET and TFTP are important applications in an overall systems administration strategy. They both have the shortcoming of not encrypting their data and therefore need to be used on secured networks for improved security. TFTP sessions don't even need a username and password, and the TFTP server process overwrites any existing file beneath its root directory in keeping with the instructions of the network engineer. Making mistakes with TFTP can be fairly easy to do, and you may want to consider automating the process by using a helper application, such as expect.

TELNET is a greater security risk as the connections are longer, and valuable usernames and passwords are exchanged, making eavesdropping easier and more lucrative for the hacker. I'd suggest that you use an encrypted TELNET replacement whenever possible. One such product, SSH, will be covered in Chapter 17, "Secure Remote Logins and File Copying."