Can't ping nodes with Private IP.
I've got three nodes each in a different region. I'm running simple ping tests such as the following:
ping -c3 192.168.X.X
node 1 can successfully ping node 2 and 3
node 2 cannot ping node 1 or 3 (3 packets transmitted, 0 received)
node 3 cannot ping node 2 (3 packets transmitted, 0 received)
I've searched around in the forums and tinked with a few things here and there (ufw and iptables), but I'm not an expert in networking so hoping somebody has some advice for how to best troubleshoot this.
Edit:
All nodes are running Ubuntu 20.04.4 LTS
1 Reply
✓ Best Answer
ping -c3 192.168.X.X
This is the way it's supposed to work. Per RFC1918, IP addresses in the following networks are unroutable (traffic to/from them cannot cross a router):
- 10.0.0.0/8 (range: 10.0.0.0 – 10.255.255.255)
- 172.16.0.0/12 (range: 172.16.0.0 – 172.31.255.255)
- 192.168.0.0/16 (range: 192.168.0.0 – 192.168.255.255)
See:
https://en.wikipedia.org/wiki/Reserved_IP_addresses
https://www.rfc-editor.org/rfc/rfc1918
If you look at the list of active DHCP leases in your home wifi router, you'll see a list of addresses in one of these networks.
Generally, you should consider "private" IP addresses to be just that…local to a LAN in the data center where your Linode resides and not reachable by any system external to that LAN.
The successes you're seeing are probably due to quirks/flaws in Linode's network topology (which they may or may not discuss with you). You should not ever count on the quirk/flaw that may exist now to be a permanent state of affairs.
-- sw