Our recommendations ...



MS Windows

For Microsoft Windows, we recommend version 2.4 of the SSH Windows Secure Shell, a comprehensive and easy to use package that includes the full suite of ssh2 tools as well as the sftp2 FTP client (a replacement for FTP that uses ssh2 protocols for the file transfer connection). Please note that this package supports ssh2 only and cannot be used to connect to systems that only support ssh1.

An alternative Windows client is putty which supports ssh1 only. Rather limited in comparison with SSH Windows Secure Shell, it may appeal to those of you who are used to the X-Windows environment - if your Windows PC has a 3 button mouse, all three buttons operate in the same way as they do in X-Windows and putty behaves very much like xterm.

For maximum flexibility, install both!

Linux

By far the best way to install SSH on a Linux or Unix system is to build it yourself from source - this way, the package is built using the libraries installed on your system and it will match your own system's environment. You can also decide where you want it installed in your filesystem, and there are many optional features of SSH you can choose to include or omit from your build.

However, if your Linux system is RPM-based (Red Hat, SuSE, Mandrake, etc) or uses the Debian .deb packaging system then you may prefer to download pre-built SSH RPMs or .deb packages from your Linux vendor's web site and install them using RPM, YaST, dselect or whatever installation system your distribution uses. Be warned that you'll get OpenSSH (see below) and you need to make sure that you get the correct RPM or .deb for your system - an RPM for Red Hat 7 will not install or run on a Red Hat 6.2 system, nor will it work with SuSE 7.0.

Assuming you want to build SSH yourself on your own system, there are now two main distribution trees for SSH - the original SSH and OpenSSH. I recommend the original SSH as you have a choice of ssh1 or ssh2 (or both) and the ssh2 package includes sftp2, the secure FTP replacement. OpenSSH does not support ssh1 and has no equivalent to sftp2; it is very much in its infancy and there are known interoperability problems between OpenSSH and SSH, or between an OpenSSH client on one system and an OpenSSH server on another.

You can download ssh1 or the latest version of ssh2; if you have a Debian 2.1 system, you may have problems building the latest version of ssh2 (version 2.4.0) and the the earlier version 2.0.13 is recommended instead.
It is up to you whether you install only ssh1 or only ssh2 but for maximum flexibility it is recommended you install both so that you'll be able to connect to any ssh system no matter what version it supports. If you do this, be sure to install ssh1 first and then ssh2 afterwards - the ssh2 install script that runs after you build it has a very nice feature that renames the old ssh1 files and then links them in such a way that the two packages are integrated.

The Unix/Linux versions of SSH build a lot of other things on your system as well - the scp program (an encrypted replacement for the original Unix rcp program) and various utilities to generate your own host and server private and public keys.

Finally, OpenSSH is an ongoing project and is improving all the time so it is worth keeping up to date with developments on their web site.

Unix

Much the same applies to Unix as for Linux - SSH builds and installs easily on Digital/Compaq Alphas running Digital Unix 3.x (aka OSF/1), 4.0D or 4.0E and also on Silicon Graphics systems runnng IRIX 6.5 or later. If you have a Sun running Solaris, you'll need to install a C complier as Solaris does not include this as part of the standard operating system installation. Sun's own C compiler is not ANSI-compliant and is known to have problems compiling SSH (and most other packages for that matter) so the best thing is to install the GNU gcc package before you attempt to build SSH.

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Andy Thomas

Unix/network sys admin,
Department of Mathematics

last updated: 2.12.00