This diagram can guide you through a step-by-step process to troubleshoot common issues with Check Point Firewall IPSec VPN connections:

Start

• Is the VPN tunnel not establishing at all? (No connectivity)
• -> Yes
  • Go to Step 1: Connectivity Checks
• Is the VPN tunnel established but traffic is not flowing?
• -> Yes
  • Go to Step 4: Traffic Flow Verification
• Is the VPN tunnel operational, but you suspect performance issues?
• -> Yes
  • Go to Step 7: Performance Optimization

Step 1: Connectivity Checks

Sample Troubleshooting:

• Command: ping <remote_gateway_ip> from the local firewall.

Expected Result: Successful ping reply from the remote gateway.

Sample Log (if ping fails):

PING <remote_gateway_ip> (xxx.xxx.xxx.xxx) 56(84) bytes of data. From 192.168.1.10 icmp_seq=1 ttl=64 time=1000ms --- <remote_gateway_ip> ping statistics --- 1 packets transmitted, 0 received, 100% packet loss, time 1000ms

Troubleshooting Steps:

1.1. Verify basic network connectivity between the firewalls using ping or traceroute from one firewall to the other's public IP. If pings fail, check network connectivity issues between the firewalls.

1.2. Check the status of the VPN tunnel interface on both firewalls. It should show "Up" if established. You can use the command: show vpn tunnels

Step 2: IKE Negotiation Analysis (if applicable from Step 1.3)

Sample Troubleshooting:

• Command: show log all | grep ike on both firewalls.