How do I allow pings through cloud firewalls?
Linode
Linode Staff
I'm using the Freshping service to monitor uptime, but the Cloud Firewalls service is blocking the ICMP Ping. How can I whitelist this? I tried accept 80/443 ports, but it still doesn't work.
2 Replies
JGenereux
Linode Staff
Hi there,
You can allow icmp pings through your Cloud Firewall by adding a inbound rule to your firewall that allows it. Generally the default inbound policy is likely set to drop. To create a rule that will allow your Linode to be pinged:
- Navigate to the Cloud Firewall you'd like to modify.
- Add a new inbound rule with the button in the top right corner.
- Leave the preset option on the default option
- You can label this new rule and include a description if you like. The most important fields will be the
ProtocolandSourcesfields. - Under Protocol select ICMP
- Under sources you can limit who can ping this Linode. If you aren't concerned with others pinging your Linode you can set this to all IPv4 and IPv6 or limit it to a single IP.
- Don't forget to save changes!
Incase it's helpful I've included a link to the Getting Started with Linode Firewalls guide.
I'm not super familiar with Freshping, so I'm not completely sure what the best settings would be for you, but I hope this helps get your monitoring up and running.
I tried accept 80/443 ports, but it still doesn't work.
Just so you know, ICMP Echo Request/Response (aka ping) is neither a TCP (like HTTP -- port 80/443) nor UDP (like DNS -- port 53) service. It's ICMP (Internet Control Message Protocol).
Except for ping, it's a very bad idea™ to block ICMP messages. ICMP is an integral part of IP. It's used by the network infrastructure to manage itself and to deal with problems -- congestion, re-routing, etc.
See: https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol
-- sw