etelnet <host> [<port_number>] loginid password
The etelnet command is similar to the telnet command (which see), but it accepts the login id and password to be provided to the <host> system. Etelnet will encrypt the password if the <host> system supports MD5 authentication (as indicated by a [hex_number] challenge value in its password prompt). If no such challenge is provided, the password is sent "in the clear".
If you are telnetting to a port/service that does not provide a password prompt, then telnet should be used instead of etelnet.
The etelnet command is available when JNOS was compiled with #define MD5AUTHENTICATE.