VPN - IKEv2 peer address of 0.0.0.0 0.0.0.0
When applying various VPN technologies including IKE, FlexVPN, and other related technologies of the IPSec suite, a peer address must be specified. This peer address indicates the IPv4 or IPv6 address of the remote peer.
For example, the following configuration specifies the peer address under the crypto configuration:
crypto ikev2 keyring MY_KEY peer MY_VPN address 0.0.0.0 0.0.0.0
The crypto ikev2 keyring MY_KEY command is used to define a keyring named MY_KEY, which is a repository of pre-shared keys or certificates that the device can use to authenticate the remote peer during the IKEv2 negotiation process.
Within that keyring, a peer named MY_VPN is defined. The address 0.0.0.0 0.0.0.0 line under this peer configuration is particularly interesting. Here's what it means:
- The first
0.0.0.0specifies the IP address of the peer. In this context,0.0.0.0acts as a wildcard address. - The second
0.0.0.0is the subnet mask, which, when set to0.0.0.0, means that any address would match.
So, in essence, address 0.0.0.0 0.0.0.0 under a peer configuration in a Cisco IKEv2 keyring setup means that this peer configuration applies to any and all IP addresses. This is typically used in scenarios where you either do not know the IP address of the peer in advance, the IP address is dynamically assigned, or you want the configuration to be applicable to any peer IP address.
It's a way to make the VPN configuration more flexible, hence the peer name MY_VPN could be indicative of its intended use for flexible VPN setups. This configuration allows the device to attempt to authenticate any peer trying to establish an IKEv2 connection using the keys or certificates specified in the MY_KEY keyring.