Demonstrations of tcpstates, the Linux BPF/bcc version.


tcpstates prints TCP state change information, including the duration in each
state as milliseconds. For example, a single TCP session:

# tcpstates
SKADDR           C-PID C-COMM     LADDR           LPORT RADDR           RPORT OLDSTATE    -> NEWSTATE    MS
ffff9fd7e8192000 22384 curl       100.66.100.185  0     52.33.159.26    80    CLOSE       -> SYN_SENT    0.000
ffff9fd7e8192000 0     swapper/5  100.66.100.185  63446 52.33.159.26    80    SYN_SENT    -> ESTABLISHED 1.373
ffff9fd7e8192000 22384 curl       100.66.100.185  63446 52.33.159.26    80    ESTABLISHED -> FIN_WAIT1   176.042
ffff9fd7e8192000 0     swapper/5  100.66.100.185  63446 52.33.159.26    80    FIN_WAIT1   -> FIN_WAIT2   0.536
ffff9fd7e8192000 0     swapper/5  100.66.100.185  63446 52.33.159.26    80    FIN_WAIT2   -> CLOSE       0.006
^C

This showed that the most time was spent in the ESTABLISHED state (which then
transitioned to FIN_WAIT1), which was 176.042 milliseconds.

The first column is the socked address, as the output may include lines from
different sessions interleaved. The next two columns show the current on-CPU
process ID and command name: these may show the process that owns the TCP
session, depending on whether the state change executes synchronously in
process context. If that's not the case, they may show kernel details.


USAGE:

# tcpstates -h
usage: tcpstates.py [-h] [-T] [-t] [-w] [-s] [-L LOCALPORT] [-D REMOTEPORT]
                    [-Y]

Trace TCP session state changes and durations

optional arguments:
  -h, --help            show this help message and exit
  -T, --time            include time column on output (HH:MM:SS)
  -t, --timestamp       include timestamp on output (seconds)
  -w, --wide            wide column output (fits IPv6 addresses)
  -s, --csv             comma separated values output
  -L LOCALPORT, --localport LOCALPORT
                        comma-separated list of local ports to trace.
  -D REMOTEPORT, --remoteport REMOTEPORT
                        comma-separated list of remote ports to trace.
  -Y, --journal         log session state changes to the systemd journal

examples:
    ./tcpstates           # trace all TCP state changes
    ./tcpstates -t        # include timestamp column
    ./tcpstates -T        # include time column (HH:MM:SS)
    ./tcpstates -w        # wider columns (fit IPv6)
    ./tcpstates -stT      # csv output, with times & timestamps
    ./tcpstates -Y        # log events to the systemd journal
    ./tcpstates -L 80     # only trace local port 80
    ./tcpstates -L 80,81  # only trace local ports 80 and 81
    ./tcpstates -D 80     # only trace remote port 80
