Linux Network Bandwidth Monitoring: Track TCP Connections
Oct 17, 2026
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by John Britto
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1 min read
Quick Linux Tip #101 :
Question: A single TCP connection seems slow. Can I measure its real throughput?
Try: sudo iftop -i eth0 -nNP -f 'port 443'
Info: iftop acts as top for network bandwidth, tracking individual connections and displaying 2s/10s/40s moving averages to pinpoint bandwidth hogs.
Examples:
$ sudo iftop -i eth0 # Launch interactive mode without filters
$ sudo iftop -i eth0 -t -s 30 # Output text mode summary for 30 seconds
$ sudo nload eth0 # View interface-wide bandwidth graphs
Note: Install via sudo apt install iftop. Interactive controls: press s to toggle source ports, d for destination ports, and t to cycle through traffic display modes.
LinuxTeck.com
linuxteck:~$ sudo iftop -i eth0 -nNP -f 'port 443'
12.5Kb 25.0Kb 37.5Kb 50.0Kb 62.5Kb
──────────────────────────────────────────────────────────────────────────────
192.168.1.50:54321 => 203.0.113.45:443 1.23Mb 2.34Mb 3.45Mb
<= 234Kb 456Kb 678Kb
192.168.1.50:54322 => 198.51.100.22:443 567Kb 789Kb 890Kb
<= 45Kb 89Kb 123Kb
──────────────────────────────────────────────────────────────────────────────
TX: cum: 234MB peak: 5.67Mb rates: 1.79Mb 3.12Mb 4.33Mb
RX: cum: 45.6MB peak: 1.23Mb rates: 279Kb 545Kb 801Kb
TOTAL: cum: 280MB peak: 6.89Mb rates: 2.07Mb 3.67Mb 5.14Mb
linuxteck:~$
About John Britto
John Britto Founder & Chief-Editor @LinuxTeck. A Computer Geek and Linux Intellectual having more than 20+ years of experience in Linux and Open Source technologies.
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