http://www.linuxfromscratch.org/blfs/view/svn/postlfs/openssh.htmlhtml
Introduction to OpenSSHlinux
The OpenSSH package contains ssh clients and the sshd daemon. This is useful for encrypting authentication and subsequent traffic over a network. The ssh and scp commands are secure implementations of telnet and rcp respectively.app
This package is known to build and work properly using an LFS-8.3 platform.less
Package Informationssh
Download (HTTP): http://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-7.9p1.tar.gz
Download MD5 sum: c6af50b7a474d04726a5aa747a5dce8f
Download size: 1.5 MB
Estimated disk space required: 39 MB (add 12 MB for tests)
Estimated build time: 0.4 SBU (running the tests takes 17+ minutes, irrespective of processor speed)
OpenSSH Dependencieside
Optionalsvn
Linux-PAM-1.3.0, X Window System, MIT Kerberos V5-1.16.2, libedit, LibreSSL Portable, OpenSC, and libsectokpost
Optional Runtime (Used only to gather entropy)ui
OpenJDK-10.0.2, Net-tools-CVS_20101030, and Sysstat-12.0.2this
User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/OpenSSH
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 issuing the following commands as the root user:
install -v -m700 -d /var/lib/sshd &&
chown -v root:sys /var/lib/sshd &&
groupadd -g 50 sshd &&
useradd -c 'sshd PrivSep' \
-d /var/lib/sshd \
-g sshd \
-s /bin/false \
-u 50 sshd
Install OpenSSH by running the following commands:
./configure --prefix=/usr \
--sysconfdir=/etc/ssh \
--with-md5-passwords \
--with-privsep-path=/var/lib/sshd &&
make
The testsuite requires an installed copy of scp to complete the multiplexing tests. To run the test suite, first copy the scp program to /usr/bin, making sure that you backup any existing copy first.
To test the results, issue: make tests.
Now, as the root user:
make install &&
install -v -m755 contrib/ssh-copy-id /usr/bin &&
install -v -m644 contrib/ssh-copy-id.1 \
/usr/share/man/man1 &&
install -v -m755 -d /usr/share/doc/openssh-7.9p1 &&
install -v -m644 INSTALL LICENCE OVERVIEW README* \
/usr/share/doc/openssh-7.9p1
Command Explanations
--sysconfdir=/etc/ssh: This prevents the configuration files from being installed in /usr/etc.
--with-md5-passwords: This enables the use of MD5 passwords.
--with-pam: This parameter enables Linux-PAM support in the build.
--with-xauth=/usr/bin/xauth: Set the default location for the xauth binary for X authentication. Change the location if xauth will be installed to a different path. This can also be controlled from sshd_config with the XAuthLocation keyword. You can omit this switch if Xorg is already installed.
--with-kerberos5=/usr: This option is used to include Kerberos 5 support in the build.
--with-libedit: This option enables line editing and history features for sftp.
Configuring OpenSSH
Config Files
~/.ssh/*, /etc/ssh/ssh_config, and /etc/ssh/sshd_config
There are no required changes to any of these files. However, you may wish to view the /etc/ssh/ files and make any changes appropriate for the security of your system. One recommended change is that you disable root login via ssh. Execute the following command as the root user to disable root login via ssh:
echo "PermitRootLogin no" >> /etc/ssh/sshd_config
If you want to be able to log in without typing in your password, first create ~/.ssh/id_rsa and ~/.ssh/id_rsa.pub with ssh-keygen and then copy ~/.ssh/id_rsa.pub to ~/.ssh/authorized_keys on the remote computer that you want to log into. You'll need to change REMOTE_USERNAME and REMOTE_HOSTNAME for the username and hostname of the remote computer and you'll also need to enter your password for the ssh-copy-id command to succeed:
ssh-keygen &&
ssh-copy-id -i ~/.ssh/id_rsa.pub REMOTE_USERNAME@REMOTE_HOSTNAME
Once you've got passwordless logins working it's actually more secure than logging in with a password (as the private key is much longer than most people's passwords). If you would like to now disable password logins, as the root user:
echo "PasswordAuthentication no" >> /etc/ssh/sshd_config &&
echo "ChallengeResponseAuthentication no" >> /etc/ssh/sshd_config
If you added Linux-PAM support and you want ssh to use it then you will need to add a configuration file for sshd and enable use of LinuxPAM. Note, ssh only uses PAM to check passwords, if you've disabled password logins these commands are not needed. If you want to use PAM, issue the following commands as the root user:
sed 's@d/login@d/sshd@g' /etc/pam.d/login > /etc/pam.d/sshd &&
chmod 644 /etc/pam.d/sshd &&
echo "UsePAM yes" >> /etc/ssh/sshd_config
Additional configuration information can be found in the man pages for sshd, ssh and ssh-agent.
Boot Script
To start the SSH server at system boot, install the /etc/rc.d/init.d/sshd init script included in the blfs-bootscripts-20180105 package.
make install-sshd
Contents
Installed Programs:
scp, sftp, slogin (symlink to ssh), ssh, ssh-add, ssh-agent, ssh-copy-id, ssh-keygen, ssh-keyscan, and sshd
Installed Libraries:
None
Installed Directories:
/etc/ssh, /usr/share/doc/openssh-7.9p1, and /var/lib/sshd
Short Descriptions
scpis a file copy program that acts like rcp except it uses an encrypted protocol.sftpis an FTP-like program that works over the SSH1 and SSH2 protocols.sloginis a symlink to ssh.sshis an rlogin/rsh-like client program except it uses an encrypted protocol.sshdis a daemon that listens for ssh login requests.ssh-addis a tool which adds keys to the ssh-agent.ssh-agentis an authentication agent that can store private keys.ssh-copy-idis a script that enables logins on remote machine using local keys.ssh-keygenis a key generation tool.ssh-keyscanis a utility for gathering public host keys from a number of hosts.Last updated on 2018-10-23 17:57:11 -0500