The host public-key pair (1536-bit RSA) is generated during the setup of SSH Tectia Server (Section Running the Setup Script). You only need to regenerate it if you want to change your host key pair.
SSH Tectia Server for IBM z/OS includes a program that generates a key pair, ssh-keygen-g3, which is located in /opt/tectia/bin.
Generate the key pair for the server in such a way that the private key has no passphrase (option -P). The server will then start up without any operator interaction to enter a passphrase. Protect the key with file system access rules. The private key (/opt/tectia/etc/hostkey) must be accessible only by the SSHD2 user.
To (re)generate the host key, perform the following tasks:
Use su to switch to a UID 0 user (if you are not already logged in as one).
Run ssh-keygen-g3 to generate the host key, for example: