The configuration file for sshd2 /etc/ssh2/sshd2_config allows you to set options that modify the operation of the daemon. The files contain keyword-value pairs, one per line, with keywords
being case insensitive. Here are the more important keywords; a complete listing is available in the man page for sshd2(8).
Edit the sshd2_config file (vi /etc/ssh2/sshs2_config and add or change, if necessary:
# sshd2_config
# SSH 2.0 Server Configuration File
*:Port 22
ListenAddress 192.168.1.1
Ciphers blowfish
IdentityFile identification
AuthorizationFile authorization
HostKeyFile hostkey
PublicHostKeyFile hostkey.pub
RandomSeedFile random_seed
ForwardAgent no
ForwardX11 no
PasswordGuesses 3
MaxConnections 5
PermitRootLogin no
AllowedAuthentications publickey,password
RequiredAuthentications publickey,password
VerboseMode no
PrintMotd yes
CheckMail yes
UserConfigDirectory "%D/.ssh2"
SyslogFacility DAEMON
Ssh1Compatibility no
NoDelay yes
KeepAlive yes
UserKnownHosts yes
AllowHosts 192.168.1.4
DenyHosts *
QuietMode no
# subsystem definitions
subsystem-sftp sftp-server
This tells sshd2_config file to set itself up for this particular configuration setup with:
Port 22
The option Port specifies which port number the ssh2 daemon listens to for ssh incoming connection. The default port is 22.
ListenAddress 192.168.1.1
The option ListenAddress specifies the IP address of the interface network on which the ssh2 daemon server socket is bound. The default is 0.0.0.0; to improve security you may
specify only the required ones to limit possible addresses.
Ciphers blowfish
The option Ciphers specifies what cipher should be used for encrypting sessions. The blowfish uses 64-bit blocks and keys of up to 448 bits.
IdentityFile identification
The option IdentityFile specifies an alternate name for the user's identification file.
AuthorizationFile authorization
The option AuthorizationFile specifies an alternate name for the user's authorization file.
HostKeyFile hostkey
The option HostKeyFile specifies an alternate file containing the private host key. The default is /etc/ssh2/hostkey.
PublicHostKeyFile hostkey.pub
The option PublicHostKeyFile specifies an alternate file containing the public host key. The default is /etc/ssh2/hostkey.pub.
RandomSeedFile random_seed
The option RandomSeedFile specifies an alternate name for the user's random seed file.
ForwardAgent no
The option ForwardAgent specifies which connection authentication agent if any should be forwarded to the remote machine.
ForwardX11 no
The option ForwardX11 is for people that use the Xwindow GUI and want to automatically redirect X11 sessions to the remote machine. Since we set up a server and don't have
a GUI installed on it, we can safely turn this option off.
PasswordGuesses 3
The option PasswordGuesses specifies how many tries the user has when using password authentication.
MaxConnections 5
The option MaxConnections specifies what the maximum number of connections that ssh2 daemon will handle simultaneously is.
PermitRootLogin no
The option PermitRootLogin specifies whether root can log in using ssh. Never say, yes to this option.
AllowedAuthentications publickey,password
The option AllowedAuthentications specifies which authentication methods are allowed to be used. With this option the administrator can force users to complete several authentications before
they are considered authenticated.
RequiredAuthentications publickey,password
The option RequiredAuthentications related to AllowedAuthentications, specifies which authentication methods the users must complete before continuing. This parameter must be the same as
for the AllowedAuthentications option or the server will denies connection every time.
VerboseMode no
The option VerboseMode instructs the ssh2 daemon to print debugging messages about its progress. This option is helpful in debugging connection, authentication, and configuration problems.
PrintMotd yes
The option PrintMotd specifies whether the ssh2 daemon should print the content of the /etc/motd file when a user logs in interactively. The /etc/motd file is also
know as the message of the day.
CheckMail yes
The option CheckMail specifies whether the ssh2 daemon should print information about new mail you may have.
UserConfigDirectory "%D/.ssh2"
The option UserConfigDirectory specifies the default location for user-specific configuration data.
SyslogFacility DAEMON
The option SyslogFacility specifies the facility code used when logging messages from the ssh2 daemon. The facility specifies the subsystem that produced the message, in our case DAEMON.
Ssh1Compatibility no
The option Ssh1Compatibility specifies whether or not to use SSH1 compatibility code with SSH2 for ssh1 users.
NoDelay yes
The option NoDelay specifies if the socket option TCP_NODELAY should be enabled. It is recommended that you set this option to yes to improve network performance.
KeepAlive yes
The option KeepAlive specifies whether the system should send keep alive messages to the remote server. If set to yes then the death of the connection or crash of
remote machines will be properly noticed.
UserKnownHosts yes
The option UserKnownHosts specifies whether the default user's home directory $HOME/.ssh2/knownhosts/ can be used to get hosts public keys when using hostbased-authentication.
AllowHosts 192.168.1.4
The option AllowHosts specifies and control which hosts can access ssh2 services. Multiple hosts can be specified separated by spaces.
DenyHosts *
The option DenyHosts specifies and controls which hosts cannot access ssh2 services. Multiple hosts can be specified separated by spaces. The default pattern * mean all hosts.
QuietMode no
The option QuietMode specifies whether the system runs in quiet mode. This option must be set to no, because in quiet mode nothing is logged in the system log except for fatal
errors. Since we want to have information about user sessions it is preferable to disable this option.