Managing port access and OS-level firewall on your server

Default Port Access at Contabo

By default, Contabo does not restrict any port access. All servers come with full administrative permissions, meaning your server's network settings and firewall configuration are entirely up to you.

Contabo Firewall vs. OS-Level Firewall

Contabo offers two distinct layers of firewall protection. Understanding the difference helps you choose the right tool for your needs.

	Contabo Firewall	OS-Level Firewall
What it is	A network-level feature provided by Contabo	A firewall configured directly on your server's operating system
Where it runs	Outside your server, at the network level	Inside your server
Managed via	Contabo Customer Panel	Command line (e.g. iptables, UFW) or OS tools
Applies to	Inbound traffic only	Inbound and outbound traffic
Available on	VPS and VDS only	All servers (VPS, VDS, Dedicated)
Default state	Inactive until enabled; blocks all inbound traffic once assigned	Active on most OS installations by default
Outbound traffic	Unrestricted	Configurable

When to use which?

Use the Contabo Firewall if you want a simple, panel-managed solution to block unwanted inbound traffic before it even reaches your server.
Use an OS-level firewall if you need granular control, outbound rules, or are on a Dedicated Server where the Contabo Firewall is not available.
Both can be used together for layered security.

Managing Ports with iptables

To open a port:

iptables -I INPUT -m state --state NEW -m tcp -p tcp --dport <<PORT No.>> -j ACCEPT

To close a port:

iptables -I INPUT -m state --state NEW -m tcp -p tcp --dport <<PORT No.>> -j DROP

Verifying Your Configuration

Check that your services are running and listening on the correct ports:

netstat -tulpen

Review your active firewall rules:

iptables -nvL

Testing Port Accessibility

Test whether a port is reachable from outside:

telnet IPv4_address_of_the_server port

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