Man pages sections > man8 > tcpconnect-bpfcc

tcpconnect - Trace TCP active connections (connect()). Uses Linux eBPF/bcc.

tcpconnect(8) System Manager's Manual tcpconnect(8)

NAME

tcpconnect - Trace TCP active connections (connect()). Uses Linux eBPF/bcc.

SYNOPSIS

tcpconnect [-h] [-t] [-x] [-p PID] [-P PORT]

DESCRIPTION

This tool traces active TCP connections (eg, via a connect() syscall; accept() are passive connections). This can be useful for general troubleshooting to see what connections are initiated by the local server.
 
All connection attempts are traced, even if they ultimately fail.
 
This works by tracing the kernel tcp_v4_connect() and tcp_v6_connect() functions using dynamic tracing, and will need updating to match any changes to these functions.
 
Since this uses BPF, only the root user can use this tool.

REQUIREMENTS

CONFIG_BPF and bcc.

OPTIONS

-h
Print usage message.
-t
Include a timestamp column.
-p PID
Trace this process ID only (filtered in-kernel).
-P PORT
Comma-separated list of destination ports to trace (filtered in-kernel).

EXAMPLES

Trace all active TCP connections:
# tcpconnect
Trace all TCP connects, and include timestamps:
# tcpconnect -t
Trace PID 181 only:
# tcpconnect -p 181
Trace ports 80 and 81 only:
# tcpconnect -P 80,81

FIELDS

TIME(s)
Time of the call, in seconds.
PID
Process ID
COMM
Process name
IP
IP address family (4 or 6)
SADDR
Source IP address.
DADDR
Destination IP address.
DPORT
Destination port

OVERHEAD

This traces the kernel tcp_v[46]_connect functions and prints output for each event. As the rate of this is generally expected to be low (< 1000/s), the overhead is also expected to be negligible. If you have an application that is calling a high rate of connects()s, such as a proxy server, then test and understand this overhead before 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

STABILITY

Unstable - in development.

AUTHOR

Brendan Gregg

SEE ALSO

tcpaccept(8), funccount(8), tcpdump(8)
2015-08-25 USER COMMANDS