Dynamic IP addresses

Dynamic IP addresses are normally assigned to broadband and dialup users from a pool of available IP addresses allocated to the service providers.

For users needing a public IP address (meaning addresses that are valid as a node on the Internet) for applications like mail, web or application servers or for video-conferencing, service providers are able to allocate block of IP addresses for them.

They can then be further dynamically assigned to individual workstation or set as a static address for each node that requires Internet presence.

If the DNS server within your LAN supports dynamic updates, static IP addresses is not even necessary, as the changes will automatically be updated.

You will also need to harden your servers be installing the latest patches, run vulnerability scan using product like LANNETSCAN and then close up the holes detected.

Alternatively, you may want to put a firewall between your LAN and the WAN connection.