My Ubuntu 12.04LTS system currently offers OpenSSH_5.9p1 Debian-5ubuntu1.8, OpenSSL 1.0.1 14 Mar 2012. Besides being old, it does not allow me to use e.g. the option
# PubkeyAcceptedKeyTypes ssh-rsa*
sshd_config, or the option
ssh-keygen. I guess the alternative would be to compile from source the latest version, with the drawback of having to do manual updates everytime.
How secure is such a system, namely would it be moderately safe to run it on a home machine behind a router with private IP, where port 22 is mapped to the desired private IP?