Single-DES is not recommended in the SSH 2 draft protocol standards, but one or two server implementations do support it. If the algorithm PuTTY finds is below the ‘warn below here’ line, you will see a warning box when you make the connection. When you make an SSH connection, PuTTY will search down the list from the top until it finds an algorithm supported by the server, and then use that. This can help make the most of a low-bandwidth connection. This enables data compression in the SSH connection. If checked, a session is started but without a pseudo-terminal. If you select ‘1 only’ or ‘2 only’ here, PuTTY will only connect if the server you connect to offers the SSH protocol version you have specified. PuTTY will attempt to use protocol 1 if the server you connect to does not offer protocol 2, and vice versa. Instead, you can choose to run a single specific command (such as a mail user agent, for example). In SSH, you don't have to run a general shell session on the server. Pre-populating the fingerprint can be helpful when connecting through SSH tunnels, proxy servers or secure gateways. Specify an MD5-based host key fingerprint of the form displayed in PuTTY's Event Log and host key dialog box or a base64-encoded blob describing an SSH-2 public key in OpenSSH's one-line public key format. The SSH Settings page allows you to configure settings specific for SSH connections.

Putty ssh