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Strongswan configuration

StrongSwan is an IPsec-base VPN solution, focus on strong authentication mechanisms using X.509 public key certificates and optional secure storage of private keys and certificates on smartcards through a standardized PKCS#11 interface and on TPM 2.0.

Configuration Concept​

Basic configuration files are as below:

  • /home/oper/strongswan/strongswan.conf: Central configuration file

  • /home/oper/strongswan/ipsec.conf: Tunnel definitions

  • /home/oper/strongswan/ipsec.secrets: List of preshared keys

  • /home/oper/strongswan/ipsec.d: Folder for certificates

For further detail, please refer to docs.strongswan.org.

Example:

ENM(Client) connect to Proton VPN(Site)

> vim /home/oper/strongswan/ipsec.conf
conn test
 left=%defaultroute
 leftsourceip=%config
 leftauth=eap-mschapv2
 eap_identity=hKVSu61QiraPAXDY7nLWFrehB6PWTqWc
 right=nl-free-03.protonvpn.net
 rightsubnet=0.0.0.0/0
 rightauth=pubkey
 rightid=%nl-free-03.protonvpn.net
 rightca=/home/oper/strongswan/ipsec.d/cacerts/protonvpn.der
 keyexchange=ikev2
 type=tunnel
 auto=add

> vim /home/oper/strongswan/ipsec.secrets
hKVSu61QiraPAXDY7nLWFrehB6PWTqWc : EAP "5DmS79J3xrvPCi5OAV7xBM5QMytNrHip"

> cp protonvpn.der /home/oper/strongswan/ipsec.d/cacerts/

> sudo /etc/init.d/ipsec restart
> sudo ipsec up test