About sshd_config file

                         In my earlier post "SSH workings and key-exchange procedure" we came across a file responsible for SSH configuration and default settings. It is one file for system-wide configuration of SSH, file initial comment section mentions, all options are present with default values but commented. Any uncommented options will override the default value.

    We verify today what each options means. I am using sshd_config,v 1.93.

        #Port 22 : Default port to be used for making ssh connection. Can be changed 

        #AddressFamily any : Specifies which IP address family sshd should use. 

            Valid arguments are: any, inet (IPv4 only), inet6 (IPv6 only).

        #ListenAddress 0.0.0.0 : Take host:port or host as valid arguments. 0.0.0.0 means 

            any host IP.

        #Protocol : Support both SSH protocol 1 and 2. Protocol 2 supports both RSA 

            and DSA keys; protocol 1 only supports RSA keys.

        #Hostkey : Specifies a file containing a private host key used by SSH. The default

             is  /etc/ssh/ssh_host_key for protocol version 1, and /etc/ssh/ssh_host_rsa_key 

             and  /etc/ssh/ssh_host_dsa_key for protocol version 2. In case, we do not want to use 

             RSA, other supported options are /etc/ssh/ssh_host_ecdsa_key  and 

             /etc/ssh/ssh_host_ed25519_key. Elliptic Curve Digital Signature Algorithm 

            (ECDSA) offers a variant of the Digital Signature Algorithm (DSA) . 

        ######  WIP...