bcc-tcpsubnet(8)

1tcpsubnet(8)                System Manager's Manual               tcpsubnet(8)
2
3
4

NAME

6       tcpsubnet - Summarize and aggregate IPv4 TCP traffic by subnet.
7

SYNOPSIS

9       tcpsubnet [-h] [-v] [-J] [-f FORMAT] [-i INTERVAL] [subnets]
10

DESCRIPTION

12       This tool summarizes and aggregates IPv4 TCP sent to the subnets passed
13       in argument and prints to stdout on a fixed interval.
14
15       This uses dynamic tracing of kernel  TCP  send/receive  functions,  and
16       will need to be updated to match kernel changes.
17
18       The traced data is summarized in-kernel using a BPF map to reduce over‐
19       head.  At very high TCP event rates, the overhead may still be  measur‐
20       able.  See the OVERHEAD section for more details.
21
22       Since this uses BPF, only the root user can use this tool.
23

REQUIREMENTS

25       CONFIG_BPF and bcc.
26

OPTIONS

28       -h     Print USAGE message.
29
30       -v     Run  in  verbose mode. Will output subnet evaluation and the BPF
31              program
32
33       -J     Format output in JSON.
34
35       -i     Interval between updates, seconds (default 1).
36
37       -f     Format output units. Supported values  are  bkmBKM.  When  using
38              kmKM the output will be rounded to floor.
39
40       subnets
41              Comma  separated list of subnets. Traffic will be categorized in
42              theses       subnets.       Order       matters.        (default
43              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)
44

EXAMPLES

46       Summarize TCP traffic by the default subnets:
47              # tcpsubnet
48
49       Summarize all TCP traffic:
50              # tcpsubnet 0.0.0.0/0
51
52       Summarize all TCP traffic and output in JSON and Kb:
53              # tcpsubnet -J -fk 0.0.0.0/0
54

FIELDS

56       (Standad output) Left hand side column:
57              Subnet
58
59       (Standard output) Right hand side column:
60              Aggregate traffic in units passed as argument
61
62       (JSON output) date
63              Current date formatted in the system locale
64
65       (JSON output) time
66              Current time formatted in the system locale
67
68       (JSON output) entries
69              Map of subnets to aggregates. Values will be in format passed to
70              -f
71

OVERHEAD

73       This traces all tcp_sendmsg function calls in  the  TCP/IP  stack.   It
74       summarizes  data  in-kernel  to  reduce  overhead.  A simple iperf test
75       (v2.0.5) with the default values shows a loss of ~5% throughput. On  10
76       runs  without  tcpsubnet  running the average throughput was 32.42Gb/s,
77       with tcpsubnet enabled it was 31.26Gb/s.  This is not meant to be  used
78       as  a  long  running  service. Use it for troubleshooting or for a con‐
79       trolled interval. As always, try it out in a test environment first.
80
81

SOURCE

83       This is from bcc.
84
85              https://github.com/iovisor/bcc
86
87       Also look in the bcc distribution for a  companion  _examples.txt  file
88       containing example usage, output, and commentary for this tool.
89

OS

91       Linux
92

STABILITY

94       Unstable - in development.
95

AUTHOR

97       Rodrigo Manyari
98

INSPIRATION

100       tcptop(8) by Brendan Gregg
101