NAME¶

tcptracer - Trace TCP established connections. Uses Linux eBPF/bcc.

SYNOPSIS¶

tcptracer [-h] [-v] [-p PID] [-N NETNS] [--cgroupmap MAPPATH] [--mntnsmap MAPPATH] [-4 | -6]

DESCRIPTION¶

This tool traces established TCP connections that open and close while tracing, and prints a line of output per connect, accept and close events. This includes the type of event, PID, IP addresses and ports.

This tool works by using kernel dynamic tracing, and will need to be updated if the kernel implementation changes. Only established TCP connections are traced, so it is expected that the overhead of this tool is rather low.

Since this uses BPF, only the root user can use this tool.

REQUIREMENTS¶

CONFIG_BPF and bcc.

OPTIONS¶

-h

Print usage message.

-v

Print full lines, with long event type names and network namespace numbers.

-p PID

Trace this process ID only (filtered in-kernel).

-N NETNS

Trace this network namespace only (filtered in-kernel).

--cgroupmap MAPPATH

Trace cgroups in this BPF map only (filtered in-kernel).

--mntnsmap MAPPATH

Trace mount namespaces in the map (filtered in-kernel).

-4

Trace IPv4 family only.

-6

Trace IPv6 family only.

EXAMPLES¶

Trace all TCP established connections:

# tcptracer

Trace all TCP established connections with verbose lines:

# tcptracer -v

Trace PID 181 only:

# tcptracer -p 181

Trace connections in network namespace 4026531969 only:

# tcptracer -N 4026531969

Trace a set of cgroups only (see special_filtering.md from bcc sources for more details):

# tcptracer --cgroupmap /sys/fs/bpf/test01

Trace IPv4 family only:

# tcptracer -4

Trace IPv6 family only:

# tcptracer -6

FIELDS¶

TYPE

Type of event. In non-verbose mode: C for connect, A for accept, X for close.

PID

Process ID

COMM

Process name

IP

IP address family (4 or 6)

SADDR

Source IP address.

DADDR

Destination IP address.

SPORT

Source port.

DPORT

Destination port.

NETNS

Network namespace where the event originated.

OVERHEAD¶

This traces the kernel inet accept function, and the TCP connect, close, and set state functions. However, it only prints information for connections that are established, so it shouldn't have a huge overhead.

As always, test and understand this tools overhead for your types of workloads before production use.

SOURCE¶

This is from bcc.

https://github.com/iovisor/bcc

Also look in the bcc distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool.

OS¶

Linux

AUTHOR¶

Iago López Galeiras

SEE ALSO¶

tcpaccept(8), tcpconnect(8), tcptop(8), tcplife(8)