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1. Prerequisites
You will need working installations of Zlib and OpenSSL.
OpenSSL 0.9.6 or greater:
(OpenSSL 0.9.5a is partially supported, but some ciphers (SSH protocol 1
Blowfish) do not work correctly.)
OpenSSH can utilise Pluggable Authentication Modules (PAM) if your system
supports it. PAM is standard on Redhat and Debian Linux, Solaris and
HP-UX 11.
NB. If you operating system supports /dev/random, you should configure
OpenSSL to use it. OpenSSH relies on OpenSSL's direct support of
/dev/random. If you don't you will have to rely on ssh-rand-helper, which
is inferior to a good kernel-based solution.
If you wish to build the GNOME passphrase requester, you will need the GNOME
libraries and headers.
Alternatively, Jim Knoble <> has written an excellent X11
passphrase requester. This is maintained separately at:
If your system lacks Kernel based random collection, the use of Lutz
Jaenicke's PRNGd is recommended.
The Entropy Gathering Daemon (EGD) is supported if you have a system which
lacks /dev/random and don't want to use OpenSSH's internal entropy collection.
S/Key Libraries:
If you wish to use --with-skey then you will need the above library
installed. No other current S/Key library is currently known to be
2. Building / Installation
To install OpenSSH with default options:
make install
This will install the OpenSSH binaries in /usr/local/bin, configuration files
in /usr/local/etc, the server in /usr/local/sbin, etc. To specify a different
installation prefix, use the --prefix option to configure:
./configure --prefix=/opt
make install
Will install OpenSSH in /opt/{bin,etc,lib,sbin}. You can also override
specific paths, for example:
./configure --prefix=/opt --sysconfdir=/etc/ssh
make install
This will install the binaries in /opt/{bin,lib,sbin}, but will place the
configuration files in /etc/ssh.
If you are using PAM, you may need to manually install a PAM control
file as "/etc/pam.d/sshd" (or wherever your system prefers to keep
them). Note that the service name used to start PAM is __progname,
which is the basename of the path of your sshd (e.g., the service name
for /usr/sbin/osshd will be osshd). If you have renamed your sshd
executable, your PAM configuration may need to be modified.
A generic PAM configuration is included as "contrib/sshd.pam.generic",
you may need to edit it before using it on your system. If you are
using a recent version of Red Hat Linux, the config file in
contrib/redhat/sshd.pam should be more useful. Failure to install a
valid PAM file may result in an inability to use password
authentication. On HP-UX 11 and Solaris, the standard /etc/pam.conf
configuration will work with sshd (sshd will match the other service
There are a few other options to the configure script:
--with-pam enables PAM support.
--enable-gnome-askpass will build the GNOME passphrase dialog. You
need a working installation of GNOME, including the development
headers, for this to work.
--with-prngd-socket=/some/file allows you to enable EGD or PRNGD
support and to specify a PRNGd socket. Use this if your Unix lacks
/dev/random and you don't want to use OpenSSH's builtin entropy
collection support.
--with-prngd-port=portnum allows you to enable EGD or PRNGD support
and to specify a EGD localhost TCP port. Use this if your Unix lacks
/dev/random and you don't want to use OpenSSH's builtin entropy
collection support.
--with-lastlog=FILE will specify the location of the lastlog file.
./configure searches a few locations for lastlog, but may not find
it if lastlog is installed in a different place.
--without-lastlog will disable lastlog support entirely.
--with-sia, --without-sia will enable or disable OSF1's Security
Integration Architecture. The default for OSF1 machines is enable.
--with-kerberos4=PATH will enable Kerberos IV support. You will need
to have the Kerberos libraries and header files installed for this
to work. Use the optional PATH argument to specify the root of your
Kerberos installation.
--with-afs=PATH will enable AFS support. You will need to have the
Kerberos IV and the AFS libraries and header files installed for this
to work. Use the optional PATH argument to specify the root of your
AFS installation. AFS requires Kerberos support to be enabled.
--with-skey=PATH will enable S/Key one time password support. You will
need the S/Key libraries and header files installed for this to work.
--with-tcp-wrappers will enable TCP Wrappers (/etc/hosts.allow|deny)
support. You will need libwrap.a and tcpd.h installed.
--with-md5-passwords will enable the use of MD5 passwords. Enable this
if your operating system uses MD5 passwords without using PAM.
--with-utmpx enables utmpx support. utmpx support is automatic for
some platforms.
--without-shadow disables shadow password support.
--with-ipaddr-display forces the use of a numeric IP address in the
$DISPLAY environment variable. Some broken systems need this.
--with-default-path=PATH allows you to specify a default $PATH for sessions
started by sshd. This replaces the standard path entirely.
--with-pid-dir=PATH specifies the directory in which the file is
--with-xauth=PATH specifies the location of the xauth binary
--with-ipv4-default instructs OpenSSH to use IPv4 by default for new
connections. Normally OpenSSH will try attempt to lookup both IPv6 and
IPv4 addresses. On Linux/glibc-2.1.2 this causes long delays in name
resolution. If this option is specified, you can still attempt to
connect to IPv6 addresses using the command line option '-6'.
--with-ssl-dir=DIR allows you to specify where your OpenSSL libraries
are installed.
--with-4in6 Check for IPv4 in IPv6 mapped addresses and convert them to
real (AF_INET) IPv4 addresses. Works around some quirks on Linux.
--with-sectok=DIR allows for OpenSC or sectok smartcard libraries to
be used with OpenSSH. See 'README.smartcard' for more details.
If you need to pass special options to the compiler or linker, you
can specify these as environment variables before running ./configure.
For example:
CFLAGS="-O -m486" LDFLAGS="-s" LIBS="-lrubbish" LD="/usr/foo/ld" ./configure
3. Configuration
The runtime configuration files are installed by in ${prefix}/etc or
whatever you specified as your --sysconfdir (/usr/local/etc by default).
The default configuration should be instantly usable, though you should
review it to ensure that it matches your security requirements.
To generate a host key, run "make host-key". Alternately you can do so
manually using the following commands:
ssh-keygen -t rsa1 -f /etc/ssh/ssh_host_key -N ""
ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key -N ""
ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key -N ""
Replacing /etc/ssh with the correct path to the configuration directory.
(${prefix}/etc or whatever you specified with --sysconfdir during
If you have configured OpenSSH with EGD support, ensure that EGD is
running and has collected some Entropy.
For more information on configuration, please refer to the manual pages
for sshd, ssh and ssh-agent.
4. Problems?
If you experience problems compiling, installing or running OpenSSH.
Please refer to the "reporting bugs" section of the webpage at
$Id: INSTALL,v 1.55 2002/07/25 04:36:25 djm Exp $