Additional methods may be defined as specified in [SSH-NUMBERS].
Note that the name "diffie-hellman-group1-sha1" is used for the first
defined key exchange method using an Oakley group referenced from
[RFC2412]. The Working Group first attempted to progress the
namespace scheme by using "diffie-hellman-group2-sha1" for the second
defined key exchange (kex) name. This name was never used in any
Working Group documents but was discussed in the mailing list. It is
not known if this kex name was implemented in any shipping code.
During this deliberation period, the Working Group wanted to provide
for a better naming scheme and attempted to follow the numbering
scheme of group numbers from [RFC3526]. This resulted in the
selection of "diffie-hellman-group14-sha1" rather than
"diffie-hellman-group2-sha1" which the Working Group felt was not as
descriptive. After this name was generally approved by consensus and
started appearing in subsequent Internet Drafts (and shipping code),
it was noted that the numbers associated with the groups in [RFC3526]
were assigned by the IANA and may be changed in the future, or that
numbers may not be used at all. This caused some indecision within
the Working Group which was resolved at the Working Group meeting at
the 60th IETF with the formal adoption of the
"diffie-hellman-group14-sha1" name for the second defined kex method.
This inconsistency should not be repeated in the future. Future
groups borrowed from [RFC2412] or its successors should not attempt
to associate SSH kex algorithms with numbers from [RFC3526]. The
naming of future specifications of Diffie-Hellman kex methods using
Oakley groups defined in [RFC2412] or its successors should be
performed with forethought and care. It will probably be best if
future names are unique to SSH and not dependent upon any external
naming or numbering schemes. Authors of future kex proposals may
wish to consider the use of "diffie-hellman-group3-sha1" or
"diffie-hellman-group15-sha1" for the next name.