Host keys should be generated on startup to be different on different instances

Makefile

@@ -13,6 +13,7 @@ all: sshd-service
 	cd openssh-8.3p1 && install -v -m644 contrib/ssh-copy-id.1 /usr/share/man/man1
 	install -v -m755 -d /usr/share/doc/openssh-8.3p1
 	cd openssh-8.3p1 && install -v -m644 INSTALL LICENCE OVERVIEW README* /usr/share/doc/openssh-8.3p1
+	rm /etc/ssh/*_key /etc/ssh/*_key.pub
 	@echo "$$SSHD_SERVICE" > /lib/systemd/system/sshd.service
 	ln -s /lib/systemd/system/sshd.service /etc/systemd/system/multi-user.target.wants/sshd.service
 	sed -i 's/#PermitRootLogin.*/PermitRootLogin yes/' /etc/ssh/sshd_config
@@ -25,6 +26,7 @@ define SSHD_SERVICE
 Description=OpenSSH Daemon
 
 [Service]
+ExecStartPre=/usr/bin/ssh-keygen -A
 ExecStart=/usr/sbin/sshd -D
 ExecReload=/bin/kill -HUP $MAINPID
 KillMode=process