DigitalOcean firewall blocks StrongSwan traffic when all ports are enabled

Posted October 30, 2021
DigitalOcean VPC VPN

I am using StrongSwan to setup a site-to-site VPN between two DigitalOcean VPCs. For testing purposes I have UFW disabled and when I add a DO firewall with TCP/UDP/ICMP open to all addresses inbound / outbound - ICMP fails to get through the tunnel. Removing the DO firewall ICMP gets through.

UFW works fine in both directions. Any ideas why the DO firewall doesn’t work?

keneshhagard

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Janusz Szeligowski • October 30, 2021

Hi,

Firstly, I must admit that I used to use DO firewall just during initial droplet configuration, to protect it until its own firewall is installed and configured. Though I do not use DO firewall on a daily basis as it is not flexible and difficult for troubleshooting (the logs are not available), I may say that the below settings made my DO firewall transparent in my implementations when I was using it.

Inbound rules.