tcprtt(8)

Welcome to the System Manager's Manual page for tcprtt(8) 💖✨

🌸 NAME 🌸

okay so tcprtt is the tool that traces the RTT (round-trip time) of TCP connections that are already established 🦋 It's built on Linux eBPF/bcc, so it's giving low-level and I'm obsessed 🔥

🧚 SYNOPSIS 🧚

tcprtt [-h] [-T] [-D] [-m] [-p LPORT] [-P RPORT] [-a LADDR] [-A RADDR]
       [-i INTERVAL] [-d DURATION] [-b] [-B] [-e] [-4 | -6]

💅 DESCRIPTION 💅

bestie, this tool watches the RTT of established connections so you can figure out how healthy the network is 🫶 It's super useful for troubleshooting, because it helps you tell whether the latency is coming from a user process or from the physical network. Main character energy 👑

Since this uses BPF, only the root user can use this tool. Not you, not me, only root 💀

📋 REQUIREMENTS 📋

You need CONFIG_BPF and bcc. No cap, those are the must-haves 🎀

✨ OPTIONS ✨

• -h — Prints the usage message 💜
• -T — Adds a time column to the output, formatted as HH:MM:SS ⏰
• -D — Shows debug information for the bpf text 🙈
• -m — Outputs the histogram in milliseconds 🍓
• -i INTERVAL — Prints output every INTERVAL seconds ✨
• -d DURATION — The total duration of the trace, in seconds ⭐
• -p LPORT — Filters for a local port 🦋
• -P RPORT — Filters for a remote port 🦋
• -a LADDR — Filters for a local address 🌈
• -A RADDR — Filters for a remote address 🌈
• -b — Shows the sockets histogram by local address 🫶
• -B — Shows the sockets histogram by remote address 🫶
• -e — Shows the extension summary, as an average 🔥
• -4 — Traces the IPv4 family only 💖
• -6 — Traces the IPv6 family only 💖

🎀 EXAMPLES 🎀

Trace TCP RTT and print 1 second summaries, 10 times:

# tcprtt -i 1 -d 10

Summarize in milliseconds, with timestamps:

# tcprtt -m -T

Only trace TCP RTT for remote address 192.168.1.100 and remote port 80:

# tcprtt -i 1 -d 10 -A 192.168.1.100 -P 80

Trace a local port and show a breakdown of remote hosts' RTT:

# tcprtt -i 3 --lport 80 --byraddr

Trace IPv4 family only:

# tcprtt -4

Trace IPv6 family only:

# tcprtt -6

🔥 OVERHEAD 🔥

This traces the kernel tcp_rcv_established function and collects TCP RTT. The rate depends on your server application 💀 If it's a web or proxy server accepting many tens of thousands of connections per second, the overhead is going to be real.

🌈 SOURCE 🌈

This is from bcc 🦋

https://github.com/iovisor/bcc

Also look in the bcc distribution for a companion _examples.txt file. It has example usage, output, and commentary for this tool, and it's honestly such a good read 📚🎀

💜 OS 💜

Linux 🐧

🫧 STABILITY 🫧

Unstable, it's still in development 🙈

👑 AUTHOR 👑

zhenwei pi, the queen behind this one ✨

🌸 SEE ALSO 🌸

tcptracer(8), tcpconnect(8), funccount(8), tcpdump(8) 💖

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Okay bestie, that's the whole page! 🎀 It's from the USER COMMANDS section, dated 2020-08-23, and it's all about tcprtt(8). Go slay your network debugging 💅🌸🦋