Some users have an IP address that changes regularly, The changing IP address can be on either the m0n0wall device or the remote IPSec VPN client. For example a dialup account, DSL Internet modem or simply moving a laptop computer from one wireless hotspot to another all can cause IP addresses that change. While the changing IP address does not affect normal Internet usage, it will break IPSec tunnels that are configured to use a specific DNS name or IP address.

A dynamic DNS name will allow you to keep the same name and can be used with m0n0wall. M0n0wall version 1.2 supports dynamic DNS for its own interface but does not support a domain name for the remote user of the VPN connection. M0n0wall 1.3b supports domain names on both sides.

Any changes to your IPSec configuration will cause all IPSec tunnels to be closed when the changes are applied.

Not at this time. The only way to achieve this would be to have multiple IPsec connections for each subnet.

Not at this time. This would be useful if 2 or more networks use the same subnet and are trying to communicate with each other over an IPsec connection.

By default, fragmented packets are not allowed to be encrypted. This default can be changed in the System > Advanced > Miscellaneous menu by checking the "Allow fragmented IPsec packets" box. When activated, this will cause m0n0wall to allow fragmented IP packets that are encapsulated in IPsec ESP packets.

By default, if several Security Associations (SAs) match, the newest one is preferred if it's at least 30 seconds old. This default can be changed in the System > Advanced > Miscellaneous menu by checking the "Prefer old IPsec SAs" When activated, this option always prefers old SAs over new ones.

When traffic is attempting to reach a network or IP address that is configured to be on a remote IPsec connection, m0n0wall will attempt to build the connection.

It won't work. It's not the same kind of IPsec client required by m0n0wall. However some users have reported success when using the NAT-T feature (i.. encapsulating encrypted traffic in UDP packets.) FIXME - verify this.

Part of the IPsec configuration identifies local and remote networks. IP addresses that are outside of those networks are not authorized to travel through an IPsec connection. This means that if you have additional routed networks connected to your LAN, they may not be able to travrse the IPsec connection because they do not originate from the LAN itself.

If you have an additional network or subnet that you want to travel through IPsec you can make additional tunnels or optionally put a NAT device between the LAN network and the other subnets so that traffic from the additional network will appear to be coming from the authorized network.

Not with IPsec. Broadcasts don't cross broadcast domains. In the case of a VPN link, each network is its own broadcast domain. Normally you don't want to connect broadcast domains because most networks have more broadcast traffic than you want to push over a VPN connection.