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.TH tcpconnect 8 "2015-08-25" "USER COMMANDS"
.SH NAME
tcpconnect \- Trace TCP active connections (connect()). Uses Linux eBPF/bcc.
.SH SYNOPSIS
.B tcpconnect [\-h] [\-t] [\-x] [\-p PID] [-P PORT]
.SH 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.
.SH REQUIREMENTS
CONFIG_BPF and bcc.
.SH OPTIONS
.TP
\-h
Print usage message.
.TP
\-t
Include a timestamp column.
.TP
\-p PID
Trace this process ID only (filtered in-kernel).
.TP
\-P PORT
Comma-separated list of destination ports to trace (filtered in-kernel).
.SH EXAMPLES
.TP
Trace all active TCP connections:
#
.B tcpconnect
.TP
Trace all TCP connects, and include timestamps:
#
.B tcpconnect \-t
.TP
Trace PID 181 only:
#
.B tcpconnect \-p 181
.TP
Trace ports 80 and 81 only:
#
.B tcpconnect \-P 80,81
.SH FIELDS
.TP
TIME(s)
Time of the call, in seconds.
.TP
PID
Process ID
.TP
COMM
Process name
.TP
IP
IP address family (4 or 6)
.TP
SADDR
Source IP address.
.TP
DADDR
Destination IP address.
.TP
DPORT
Destination port
.SH 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.
.SH SOURCE
This is from bcc.
.IP
https://github.com/iovisor/bcc
.PP
Also look in the bcc distribution for a companion _examples.txt file containing
example usage, output, and commentary for this tool.
.SH OS
Linux
.SH STABILITY
Unstable - in development.
.SH AUTHOR
Brendan Gregg
.SH SEE ALSO
tcpaccept(8), funccount(8), tcpdump(8)