Just 3 simple and useful Linux networking tricks which sometimes can be useful to quickly achieve what you want. This is nothing special, just handy examples.
Get the external IP from within the node
Lets say you have node behind WAF, Load Balancer and 7 proxies. Just make sure you have capability to make egress traffic.
You got your internet facing IP. If this domain is down, there are a myriad of others online.
Get open ports with lsof
Simple lsof command is all you need.
sudo lsof -nP -iTCP -iUDP
Fuzzy find Operating System of the node
This uses nmap to guess node operating system based on networking stack characteristics. The TCP/IP stack leaks this information.
nmap -O $HOST_IP
If you want to make it a bit harder to guess your system, you can do it with eBPF.