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Chapter 4: SSH Features > SSH vs. Telnet/Rlogin - Pg. 77

SSHFeatures·Chapter4 77 As other standards become accepted by the industry at large they may be used with SSH. During key exchanges a hashing algorithm is used to send secure key information from the two systems. The hashing algorithms currently supported in SSH in the SSH-TRANS packets are: diffie- hellman-group1-sha1 and diffie-hellman-group14-sha1. The diffie-hellman portion of the above algorithms are named for the two people who developed the algorithm: Whitfield Diffie and Martin Hellman. The group number 1 or 14 is the SSH accepted group space numbers and sha1 is the Secure Hashing Algorithm version 1. These two methods of key hashing are the current standards; legacy standards like MD5 (Message Digest v5) and MD4 (Message Digest v4) have been breached with increasing frequency and are not currently recommended. Between the encryption standards and hashing algorithms we have an effective and secure way to send and receive data from client and server. SSH vs. Telnet/Rlogin Both rlogin and telnet were developed when the internet was still a private government network (ARPAnet) and was only used by government and university researchers in a closed environment. During those days security was not as much an issue as the number of users was controlled and personal computers had not become the standard. In the mainframe world, packet capture and accessing other people's data was not unheard of, but much less common.