Show established TCP connections

All established TCP connections with process info

ss -tnp state established

More linux commands

Count connections per state

ss -tan | awk 'NR>1{print $1}' | sort | uniq -c | sort -rn

How many connections are in ESTABLISHED, TIME_WAIT, etc.
Traceroute with MTU discovery

mtr --report --tcp --port 443 example.com

Combine traceroute and ping; TCP mode to bypass ICMP blocks
Test MTU path

ping -M do -s 1472 -c 3 8.8.8.8

Send DF-bit ping of 1500-byte frames to detect MTU issues
Show iptables rules

iptables -L -n -v --line-numbers

All filter table rules with packet counters and line numbers
Show nftables ruleset

nft list ruleset

Full nftables ruleset in human-readable form