NAME

       tcpsubnet - Summarize and aggregate IPv4 TCP traffic by subnet.

SYNOPSIS

       tcpsubnet [-h] [-v] [-J] [-f FORMAT] [-i INTERVAL] [subnets]

DESCRIPTION

       This  tool  summarizes  and aggregates IPv4 TCP sent to the subnets passed in argument and
       prints to stdout on a fixed interval.

       This uses dynamic tracing of kernel TCP  send/receive  functions,  and  will  need  to  be
       updated to match kernel changes.

       The  traced data is summarized in-kernel using a BPF map to reduce overhead.  At very high
       TCP event rates, the overhead may still be measurable.  See the OVERHEAD section for  more
       details.

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

REQUIREMENTS

       CONFIG_BPF and bcc.

OPTIONS

       -h     Print USAGE message.

       -v     Run in verbose mode. Will output subnet evaluation and the BPF program

       -J     Format output in JSON.

       -i     Interval between updates, seconds (default 1).

       -f     Format  output  units. Supported values are bkmBKM. When using kmKM the output will
              be rounded to floor.

       subnets
              Comma separated list of subnets. Traffic will be  categorized  in  theses  subnets.
              Order                               matters.                               (default
              127.0.0.1/32,10.0.0.0/8,172.16.0.0/12,192.168.0.0/16,0.0.0.0/0)

EXAMPLES

       Summarize TCP traffic by the default subnets:
              # tcpsubnet

       Summarize all TCP traffic:
              # tcpsubnet 0.0.0.0/0

       Summarize all TCP traffic and output in JSON and Kb:
              # tcpsubnet -J -fk 0.0.0.0/0

FIELDS

       (Standad output) Left hand side column:
              Subnet

       (Standard output) Right hand side column:
              Aggregate traffic in units passed as argument

       (JSON output) date
              Current date formatted in the system locale

       (JSON output) time
              Current time formatted in the system locale

       (JSON output) entries
              Map of subnets to aggregates. Values will be in format passed to -f

OVERHEAD

       This traces all tcp_sendmsg function calls in the TCP/IP stack.  It  summarizes  data  in-
       kernel  to  reduce overhead.  A simple iperf test (v2.0.5) with the default values shows a
       loss of ~5% throughput. On 10 runs without tcpsubnet running the  average  throughput  was
       32.42Gb/s,  with  tcpsubnet  enabled  it was 31.26Gb/s.  This is not meant to be used as a
       long running service. Use it for troubleshooting or for a controlled interval. As  always,
       try it out in a test environment first.

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

       Rodrigo Manyari

INSPIRATION

       tcptop(8) by Brendan Gregg

SEE ALSO

       netlink(7)