tcpstates(8) System Manager's Manual tcpstates(8)
NAME
tcpstates - Trace TCP session state changes with durations. Uses Linux
eBPF/bcc.
SYNOPSIS
tcpstates [-h] [-T] [-t] [-w] [-s] [-D PORTS] [-L PORTS] [-Y] [-4 | -6]
DESCRIPTION
This tool traces TCP session state changes while tracing, and prints
details including the duration in each state. This can help explain the
latency of TCP connections: whether the time is spent in the ESTAB-
LISHED state (data transfer), or initialization state (SYN_SENT), etc.
This tool works using the sock:inet_sock_set_state tracepoint, which
was added to Linux 4.16. Linux 4.16 also included extra state transi-
tions so that all TCP transitions could be observed by this tracepoint.
Only TCP state changes are traced, so it is expected that the overhead
of this tool is much lower than typical send/receive tracing.
Since this uses BPF, only the root user can use this tool.
REQUIREMENTS
CONFIG_BPF and bcc, and the sock:inet_sock_set_state tracepoint.
OPTIONS
-h Print usage message.
-s Comma separated values output (parseable).
-t Include a timestamp column (seconds).
-T Include a time column (HH:MM:SS).
-w Wide column output (fits IPv6 addresses).
-L PORTS
Comma-separated list of local ports to trace (filtered in-ker-
nel).
-D PORTS
Comma-separated list of destination ports to trace (filtered in-
kernel).
-Y Log session state changes to the systemd journal.
-4 Trace IPv4 family only.
-6 Trace IPv6 family only.
EXAMPLES
Trace all TCP sessions, and show all state changes:
# tcpstates
Include a timestamp column, and wide column output:
# tcpstates -tw
Trace connections to local ports 80 and 81 only:
# tcpstates -L 80,81
Trace connections to remote port 80 only:
# tcpstates -D 80
Trace IPv4 family only:
# tcpstates -4
Trace IPv6 family only:
# tcpstates -6
FIELDS
TIME Time of the change, in HH:MM:SS format.
TIME(s)
Time of the change, in seconds.
C-PID The current on-CPU process ID. This may show the process that
owns the TCP session if the state change executes in synchronous
process context, else it is likely to show the kernel (asynchro-
nous state change).
C-COMM The current on-CPU process name. This may show the process that
owns the TCP session if the state change executes in synchronous
process context, else it is likely to show the kernel (asynchro-
nous state change).
IP IP address family (4 or 6)
LADDR Local IP address.
RADDR Remote IP address.
LPORT Local port.
RPORT Remote port.
OLDSTATE
Previous TCP state.
NEWSTATE
New TCP state.
MS Duration of this state.
OVERHEAD
This traces the kernel TCP set state function, which should be called
much less often than send/receive tracing, and therefore have lower
overhead. The overhead of the tool is relative to the rate of new TCP
sessions: if this is high, over 10,000 per second, then there may be
noticeable overhead just to print out 10k lines of formatted output per
second.
You can find out the rate of new TCP sessions using "sar -n TCP 1", and
adding the active/s and passive/s columns.
As always, test and understand this tools overhead for your types of
workloads before production 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), tcpconnect(8), tcptop(8), tcplife(8)
USER COMMANDS 2018-03-20 tcpstates(8)
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