How Do I Troubleshoot Vultr Firewall Issues?

When network traffic to your instance is unexpectedly blocked or restricted, the issue often arises from the interaction between Vultr Firewall rules and firewall software running on your instance. Vultr Firewall enforces network-level rules before traffic reaches your instance, while tools like iptables, firewalld, or UFW on the instance itself may also enforce host-level rules. Considering both layers helps you identify and resolve conflicting settings effectively.

Vultr provides Firewall groups that you can attach to one or more instances. These groups allow you to define inbound and outbound rules at the network level. Firewall groups can be managed through the Vultr Customer Portal, API, CLI, or Terraform.

If firewall rules appear ineffective, start by confirming which Firewall group is associated with your instance and checking its rule set. Then inspect the instance’s host-level firewall to ensure it does not block traffic allowed by the Vultr Firewall. You can check active rules with commands such as:

# For UFW
$ sudo ufw status verbose

# For iptables
$ sudo iptables -L -v

# For firewalld
$ sudo firewall-cmd --list-all

For example, if Vultr Firewall allows traffic on port 80, but iptables on the instance rejects it, connections will fail.

For instances behind a Vultr Load Balancer, verify that your Firewall rules allow traffic from the Load Balancer’s source IPs. Connectivity issues often arise from missing rules for health checks, service-specific traffic, or misconfigured interface zone rules on host firewalls.

Careful review of both the Vultr Firewall configuration and your instance’s host-level firewall enables you to systematically identify and resolve network access issues.