Ubuntu 17.10下StrongSwan使用问题求助

Hey there, let's dig into your StrongSwan problem on Ubuntu 17.10. Since you haven't shared the exact error or scenario yet, I'll cover the most common troubleshooting steps that resolve most issues:

1. Verify Service Status & Check Logs #

First, let's make sure StrongSwan is running and capture any error messages:

• Check the service status:

  sudo systemctl status strongswan
  

• If it's inactive, start it and watch for immediate failures:

  sudo systemctl start strongswan
  

• For real-time debugging logs (critical for connection issues), use the system journal:

  sudo journalctl -u strongswan -f
  

  The -f flag lets you follow logs as they're generated, which is perfect for testing connection attempts.

2. Validate Configuration Files #

StrongSwan relies on two key config files—let's make sure they're set up correctly:

• Run the built-in config checker to catch syntax errors in /etc/ipsec.conf:

  sudo ipsec checkconfig
  

• Ensure your /etc/ipsec.secrets (which holds pre-shared keys or certificate passwords) has strict permissions (only root should access it):

  sudo chmod 600 /etc/ipsec.secrets
  

3. Adjust Firewall & Network Settings #

Ubuntu 17.10 uses ufw by default, so we need to allow IPsec traffic and enable routing:

• Open the required UDP ports for IKE (500) and NAT-T (4500):

  sudo ufw allow 500/udp
  sudo ufw allow 4500/udp
  

• Enable IP forwarding (required if you're routing traffic through the VPN):

  sudo sysctl net.ipv4.ip_forward=1
  

  To make this permanent, edit /etc/sysctl.conf and uncomment the line net.ipv4.ip_forward=1, then run sudo sysctl -p to apply changes.

4. Fix Common Connection Failures #

Here are quick fixes for frequent issues:

• IKE negotiation fails: Double-check the remote gateway IP, pre-shared key, or certificate details in your config—typos here are the #1 cause.
• NAT traversal problems: If either your machine or the remote gateway is behind a NAT, add nat-traversal=yes to the config setup section in /etc/ipsec.conf.
• Certificate errors: If using certificate auth, confirm the CA cert is in /etc/ipsec.d/cacerts/, and that client/server certs are unexpired with the correct Common Name (CN).

If you can share the specific error message from the logs or a snippet of your ipsec.conf/ipsec.secrets (redact sensitive info!), I can give a more targeted fix.

内容的提问来源于stack exchange，提问作者Joshua S.