Chapter 11 IPsec VPN for FortiOS 5.0 : Dynamic DNS configuration : Dynamic DNS over VPN concepts : Dynamic DNS over VPN : Local ID (peer ID)
  
Local ID (peer ID)
The Local ID or peer ID can be used to uniquely identify one end of a VPN tunnel. This enables a more secure connection. Also if you have multiple VPN tunnels negotiating, this ensures the proper remote and local ends connect. When you configure it on your end, it is your Local ID. When the remote end connects to you, they see it as your peer ID.
If you are debugging a VPN connection, the Local ID is part of the VPN negotiations. You can use it to help troubleshoot connection problems.
To configure your Local ID
1. Go to VPN > IPsec > Auto Key (IKE).
2. Select Create New Phase 1 or edit an existing Phase 1 entry.
3. Select Advanced.
4. In the P1 Proposal section, enter your Local ID.
5. Select OK.
The default configuration is to accept all local IDs (peer IDs). If you have the Local ID set, the remote end of the tunnel must be configured to accept your Local ID.
To accept a specific Peer ID
1. Go to VPN > IPsec > Auto Key (IKE).
2. Select Create New Phase 1.
3. Select Aggressive mode.
4. For Peer Options, select Accept this peer ID. This option becomes visible only when Aggressive mode is selected.
5. Enter the string the other end of the tunnel used for its Local ID.
6. Configure the rest of the Phase 1 entry as required.
7. Select OK.