bcc-tcpstates(8)

1tcpstates(8)                System Manager's Manual               tcpstates(8)
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NAME

6       tcpstates  - Trace TCP session state changes with durations. Uses Linux
7       eBPF/bcc.
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SYNOPSIS

10       tcpstates [-h] [-T] [-t] [-w] [-s] [-D PORTS] [-L PORTS] [-Y]
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DESCRIPTION

13       This tool traces TCP session state changes while  tracing,  and  prints
14       details including the duration in each state. This can help explain the
15       latency of TCP connections: whether the time is  spent  in  the  ESTAB‐
16       LISHED state (data transfer), or initialization state (SYN_SENT), etc.
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18       This  tool  works  using the sock:inet_sock_set_state tracepoint, which
19       was added to Linux 4.16. Linux 4.16 also included extra  state  transi‐
20       tions so that all TCP transitions could be observed by this tracepoint.
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22       Only  TCP state changes are traced, so it is expected that the overhead
23       of this tool is much lower than typical send/receive tracing.
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25       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

28       CONFIG_BPF and bcc, and the sock:inet_sock_set_state tracepoint.
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OPTIONS

31       -h     Print usage message.
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33       -s     Comma separated values output (parseable).
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35       -t     Include a timestamp column (seconds).
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37       -T     Include a time column (HH:MM:SS).
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39       -w     Wide column output (fits IPv6 addresses).
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41       -L PORTS
42              Comma-separated list of local ports to trace  (filtered  in-ker‐
43              nel).
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45       -D PORTS
46              Comma-separated list of destination ports to trace (filtered in-
47              kernel).
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49       -Y     Log session state changes to the systemd journal.
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EXAMPLES

52       Trace all TCP sessions, and show all state changes:
53              # tcpstates
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55       Include a timestamp column, and wide column output:
56              # tcpstates -tw
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58       Trace connections to local ports 80 and 81 only:
59              # tcpstates -L 80,81
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61       Trace connections to remote port 80 only:
62              # tcpstates -D 80
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FIELDS

65       TIME   Time of the change, in HH:MM:SS format.
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67       TIME(s)
68              Time of the change, in seconds.
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70       C-PID  The current on-CPU process ID. This may show  the  process  that
71              owns the TCP session if the state change executes in synchronous
72              process context, else it is likely to show the kernel (asynchro‐
73              nous state change).
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75       C-COMM The  current on-CPU process name. This may show the process that
76              owns the TCP session if the state change executes in synchronous
77              process context, else it is likely to show the kernel (asynchro‐
78              nous state change).
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80       IP     IP address family (4 or 6)
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82       LADDR  Local IP address.
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84       RADDR  Remote IP address.
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86       LPORT  Local port.
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88       RPORT  Remote port.
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90       OLDSTATE
91              Previous TCP state.
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93       NEWSTATE
94              New TCP state.
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96       MS     Duration of this state.
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OVERHEAD

99       This traces the kernel TCP set state function, which should  be  called
100       much  less  often  than  send/receive tracing, and therefore have lower
101       overhead. The overhead of the tool is relative to the rate of  new  TCP
102       sessions:  if  this  is high, over 10,000 per second, then there may be
103       noticeable overhead just to print out 10k lines of formatted output per
104       second.
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106       You can find out the rate of new TCP sessions using "sar -n TCP 1", and
107       adding the active/s and passive/s columns.
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109       As always, test and understand this tools overhead for  your  types  of
110       workloads before production use.
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SOURCE

113       This is from bcc.
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115              https://github.com/iovisor/bcc
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117       Also  look  in  the bcc distribution for a companion _examples.txt file
118       containing example usage, output, and commentary for this tool.
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OS

121       Linux
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STABILITY

124       Unstable - in development.
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AUTHOR

127       Brendan Gregg
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