Authenticating Servers
There are two different methods that can be used to authenticate the
server (remote host computer) you are connecting to: public-key
authentication and certificate authentication.
Figure : The Server Authentication page of the Settings dialog
Security of the First Connection
When public-key authentication is used to authenticate the server, the
first connection is very important. The client asks the user to save the
host key to the local database. The fingerprint of the public key should be
verified before you save it to the local database and proceed with the
connection. If you do not verify the authenticity of the fingerprint, you risk
the possibility of a man-in-the-middle attack. For future connections, the local
copy of the server's public key will be used in server authentication.
Certificate authentication is more secure than the traditional
public-key authentication, as the system verifies that the server certificate has been
issued by a trusted certification authority (CA) and that the certificate has not
been revoked. When certificate authentication is used, a man-in-the-middle
attack is no longer a threat during key exchange, as the system verifies that
the server certificate has been issued by a trusted certification authority
(CA).
If the server certificate itself does not contain a valid authority information
access or a CRL distribution point extension, an LDAP server has to be
configured on the client-side to obtain a certificate revocation list (CRL).
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