I Came across incident where i need to troubleshoot IPSEC Site to Site connectivity issue . The term "lifetime" confuses me . please anyone explain me importance of lifetime in VPN . Whats its function . How its effect traffic flow of site to site VPN between peers.
Both IPSEC and ISAKMP create security associations (SA), which are a logical relationship between the peers specifying an encryption key. The lifetime indicates how long these associations last before they are renegotiated. When the SA is created, an encryption key is created for that SA. At the end of the lifetime, the SA is renegotiated and a new key is generated.
The purpose of lifetimes is to limit the damage if an attacker discovers the key. If the key changes periodically, the attacker will only be able to decrypt a (small) portion of the data while that key is valid.