Servers – Ensure IPv6 Outbound and Established Connections are Configured

Support > Fixing Checks > Server

06 March, 2026

This check ensures that IPv6 outbound and established connections are properly configured on the server.

Without proper rules, outbound traffic or return traffic for established connections may be blocked, leading to connectivity issues and potential service disruptions.

Check Details

Resource: Server
Check: Ensure IPv6 outbound and established connections are configured
Risk: Missing rules may block legitimate outbound traffic and established connections, causing application failures and network issues.

Remediation Steps

Open a terminal session with root or sudo privileges.
Review existing IPv6 firewall rules:
```
sudo ip6tables -L -v -n
```

Allow new and established outbound TCP connections:

sudo ip6tables -A OUTPUT -p tcp -m state --state NEW,ESTABLISHED -j ACCEPT

Allow new and established outbound UDP connections:

sudo ip6tables -A OUTPUT -p udp -m state --state NEW,ESTABLISHED -j ACCEPT

Allow new and established outbound ICMP connections:

sudo ip6tables -A OUTPUT -p icmp -m state --state NEW,ESTABLISHED -j ACCEPT

Allow established inbound TCP connections:

sudo ip6tables -A INPUT -p tcp -m state --state ESTABLISHED -j ACCEPT

Allow established inbound UDP connections:

sudo ip6tables -A INPUT -p udp -m state --state ESTABLISHED -j ACCEPT

Allow established inbound ICMP connections:

sudo ip6tables -A INPUT -p icmp -m state --state ESTABLISHED -j ACCEPT

Save the firewall rules to persist after reboot (optional but recommended).
Re-verify the rules:
```
sudo ip6tables -L -v -n
```

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Servers – Ensure IPv6 Outbound and Established Connections are Configured

Check Details

Remediation Steps