Question

DigitalOcean firewall blocks StrongSwan traffic when all ports are enabled

Posted October 30, 2021 90 views
VPNDigitalOcean VPC

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?

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1 answer

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.

Type Protocol Port Range Sources
ICMP ICMP All IPv4, All IPv6
All TCP TCP All ports All IPv4, All IPv6
SSH TCP 22 All IPv4, All IPv6
All UDP UDP All ports All IPv4, All IPv6

Outbound rules.

Type Protocol Port Range Destinations
ICMP ICMP All IPv4, All IPv6
All TCP TCP All ports All IPv4, All IPv6
All UDP UDP All ports All IPv4, All IPv6

Can you share some more info about you configuration ?

  1. Are your VPCs in the same region ?
  2. Do you have all your droplets added to to this firewall ?