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)