Increased security - Chinese walls

[lemonadesoda]

We are using vB4 on a LAN with internet access as a private communication tool within project teams and departments. There are multiple projects/teams on the server.

This is a corporate environment and we need strict confidentiality/chinese walls/data protection between projects and/or departments, e.g. HR data team1, financial data team 2, client data team3, etc, and that any backup data is archived by the correct department, securely.

Also need to ensuring lock-down from non-authorised access or sniffing over the internet,

Do you have any suggestions for tightening up security? https? encryption of SQL? Separate SQL databases by department. Note it is one server and one domain name.