http://www.rfc-editor.org/rfc/rfc4419.txt
RFC 4419: Diffie-Hellman Group Exchange for the Secure Shell (SSH) Transport Layer Protocol, M. Friedl, N. Provos, W. Simpson2006-03-01T23:00:00-00:00This memo describes a new key exchange method for the Secure Shell (SSH) protocol. It allows the SSH server to propose new groups on which to perform the Diffie-Hellman key exchange to the client. The proposed groups need not be fixed and can change with time. [STANDARDS-TRACK]