Security IKE policy hash command
When implementing IPSec on a Cisco IOS device, the hash command under the IKE policy configuration has several options:
hash {sha | sha256 | sha384 | md5}
If no hash command is used, the default is SHA.
Links:
https://forum.networklessons.com/t/encrypted-gre-tunnel-with-ipsec/999/94?u=lagapides