I'm required to configure an ipsec tunnel to communicate with a remote vpn (Cisco ASA 5555). I have created an Amazon Lightsail instance with ubuntu 18.04 installed. Upon doing some studying i came across Strongswan which I've used to configure the tunnel. The remote side provided a list of parameters I should use to configure my tunnel, I've listed them below and my settings found in ipsec.conf file. My problem is, whenever i initiate traffic to the remote side the traffic originates from my private ip (aa.aa.aa.aa) instead of my public ip AA.AA.AA.AA - since the remote side refused to use my private ip as encryption domain (something to do with it has been used in their local network) they had to allow my public ip. How can i configure strongswan such that the remote side sees traffic originating from my public ip (that way we'll have a successful tunnel connection).
Local site A:
- Public IP: AA.AA.AA.AA
- Private IP: aa.aa.aa.aa
- Subnet: aa.aa.aa.aa.aa/20
Remote site B:
- Public IP: BB.BB.BB.BB
- Private IP: bb.bb.bb.bb
- Subnet: bb.bb.bb.bb/32
Conf Parameters:
Phase 1
- Authentication method: Pre-Shared Key
- Encryption Scheme: IKE
- DH: Group 2
- Encryption Algorithm: ESP-AES-256
- Hashing Algorithm: SHA1
- Main Mode
- Lifetime (for negotiation): 86400s
Phase 2
- Encapsulation: ESP
- Encryption Algorithm: AES-256
- Authentication Algorithm: SHA1
- No PFS
- Lifetime (for negotiation): 3600s
- Key Exchange: Yes
Any help is appreciated!