This chapter is based on the manual pages (man pages) of OpenSSH and describes the OpenSSH server. The OpenSSH client is described in the interNet Services User Guide.
The description provided here has been shortened to contain only the parts relevant to BS2000. At certain places in the chapter, such as in the descriptions of options, the OpenSSH man pages are referred to as only these contain the description of the most upto-date versions. You can find the OpenSSH man pages on the Internet at https://www.openssh.com/manual.html or, after you have installed the component OpenSSH on your server,
under <installationpath>/readme/TCP-IP-SV.openssh/html/ as an HTML file,
under <installationpath>/readme/TCP-IP-SV.openssh/pdf/ as a PDF file,
under <installationpath>/readme/TCP-IP-SV.openssh/text/ as a text file.
The default installation path is: /opt/TCP-IP-SV/openssh
When the “OpenSSH man pages” are referred to in the course of this chapter, these sources are meant. The man pages supplied with the product should preferably be used as these man pages contain the BS2000-specific adaptations (changed path names, extended functionality, etc.).
SSH (Secure Shell) is a cryptographic protocol for performing the following tasks:
Login on a remote computer
Interactive / non-interactive command execution on a remote computer
File transfer between different computers in a network
SSH designates not just the protocol itself, but also concrete implementations.
Programs such as telnet, rlogin, rsh and rcp do cover the range of tasks mentioned, but they have considerable security gaps. Thus, for example, all the communication, including passwords, is generally transferred unencrypted.
SSH guarantees cryptographically secure communication over insecure networks and offers comprehensive security through
reliable, mutual authentication of the communication partners,
integrity and confidentiality of the data exchanged.
One of the intentions in developing SSH was to replace the r utilities rlogin, rsh and rcp. SSH is available in the protocol versions SSH 1 and SSH 2.
OpenSSH is a free version of SSH (i.e., there is no license fee). The OpenSSH porting to POSIX is based at the time of publication of this manual on OpenSSH V9.4, which only supports protocol version SSH 2.