Introduction to OpenSSH

The OpenSSH package contains ssh clients and the sshd daemon. This is useful for encrypting authentication and subsequent traffic over a network.

Package information

Installation of OpenSSH

OpenSSH runs as two processes when connecting to other computers. The first process is a privileged process and controls the issuance of privileges as necessary. The second process communicates with the network. Additional installation steps are necessary to set up the proper environment which are performed by the following commands:

mkdir /var/empty &&
chown root:sys /var/empty &&
groupadd sshd &&
useradd -c 'sshd privsep' -d /var/empty -g sshd -s /bin/false sshd

OpenSSH is very sensitive to changes in the linked OpenSSL libraries. If you recompile OpenSSL, OpenSSH may fail to startup. An alternative is to link against the static OpenSSL library. To link against the static library, execute the following command:

sed -i "s:-lcrypto:/usr/lib/libcrypto.a:g" configure

Install OpenSSH by running the following commands:

./configure --prefix=/usr --sysconfdir=/etc/ssh \
    --libexecdir=/usr/sbin --with-md5-passwords &&
make &&
make install

Command explanations

--sysconfdir=/etc/ssh: This prevents the configuration files from going to /usr/etc.

--with-md5-passwords: This is required if you made the changes recommended by the shadowpasswd_plus LFS hint on your SSH server when you installed the Shadow Password Suite or if you access a SSH server that authenticates by user passwords encrypted with md5.

--libexecdir=/usr/sbin: OpenSSH installs programs called by programs in /usr/libexec. sftp-server is a sshd utility and ssh-askpass is a ssh-add utility that is installed as a link to X11-ssh-askpass. Both of these should go in /usr/sbin not /usr/libexec.

Configuring OpenSSH

Config files

/etc/ssh/ssh_config, /etc/ssh/sshd_config

There are no required changes in either of these files. However you may wish to view them to make changes for appropriate security to your system. Configuration information can be found in the man pages for sshd, ssh and ssh-agent

sshd init.d script

To start the SSH Server at boot, install the /etc/rc.d/init.d/sshd init script included in the blfs-bootscripts-5.1 package.

make install-sshd


The OpenSSH package contains ssh, sshd, ssh-agent, ssh-add, sftp, scp, ssh-keygen, sftp-server and ssh-keyscan.



The basic rlogin/rsh-like client program.


The daemon that listens for ssh login requests.


An authentication agent that can store private keys.


Tool which adds keys to the ssh-agent.


FTP-like program that works over SSH1 and SSH2 protocols.


File copy program that acts like rcp.


Key generation tool.


SFTP server subsystem.


Utility for gathering public host keys from a number of hosts.