DOKK / manpages / debian 12 / nicstat / nicstat.1.en
nicstat(1) General Commands Manual nicstat(1)

nicstat, enicstat - print network traffic statistics

nicstat [-hvnsxpztualkMU] [-iinterface] [-Sint:mbps[fd|hd]] [interval [count]]

enicstat <same options & operands>

nicstat prints out network statistics for all network cards (NICs), including packets, kilobytes per second, average packet sizes and more.

Display brief usage information (help).
Display nicstat version (and additional fields when combined with '-l')
Show statistics for non-local (i.e. non-loopback) interfaces only.
Display summary output - just the amount of data received (read) and transmitted (written).
Display extended output. See OUTPUT section for details.
Display separate read and write utilization statistics. This affects the default, extended (-x) and all (-a) format outputs. For the default format the "Sat" statistic is dropped to fit the output in 80 columns.
Display interface throughput statistics in Mbps (megabits per second), instead of the default KB/s (kilobytes per second).

NOTE - interface statistics are reported to operating systems in bytes. nicstat does not know if Ethernet or other hardware overheads are included in the statistic on each platform.

Display output in parseable format. This outputs one line per interface, in the following formats (which correspond to the default, -x, -t and -u options; respectively):

time:In:rKB/s:wKB/s:rPk/s:wPk/s:%Util:Sat
time:In:rKB/s:wKB/s:rPk/s:wPk/s:%Util:Sat:IErr:OErr:Coll:NoCP:Defer
time:TCP:InKB:OutKB:InSeg:OutSeg:Reset:AttF:%ReTX:InConn:OutCon:Drops
time:UDP:InDG:OutDG:InErr:OutErr
 
where time is the number of seconds since midnight, Jan 1 1970 (UST) and the other fields are as described in the OUTPUT section below.

NOTE - throughput statistics are always in KB/s (kilbytes per second) for parseable formats, even if the "-M" flag has been specified.

Skip interfaces for which there was zero traffic for the sample period.
Show TCP statistics.
Show UDP statistics.
Equvalent to '-x -t -u'.
Just list interfaces.
Show statistics for only the interface(s) listed. Multiple interfaces can be listed, separated by commas (,).
(Linux only). Specify the speed (and optionally duplex mode) of one or more interfaces. The given speed(s) are in megabits/second. The duplex mode will default to "full" unless a suffix beginning with "h" or "H" is specified. Speed and duplex mode are obtained automatically on Solaris using the "ifspeed" and "link_duplex" kstat values.
(Solaris only). Search for active network interfaces by looking for kstat "link_state" statistics with a value of 1. This is only of value on systems running Solaris 10 (or early releases of Solaris 11 Express), with Exclusive IP Zones, where the interfaces given to an Exclusive IP Zone are not otherwise visible. If you are running Solaris 9 (or earlier), or Solaris 11 (or later) you do not need this option.

Specifies the number of seconds between samples.

Specifies the number of times that the statistics are repeated. If no count is specified, nicstat will repeat statistics indefinitely.

The fields of nicstat's display are:

The time corresponding to the end of the sample shown, in HH:MM:SS format (24-hour clock).
The interface name.
Kilobytes/second read (received).
Kilobytes/second written (transmitted).
Megabits/second read (received).
Megabits/second written (transmitted).
Packets (TCP Segments, UDP Datagrams)/second read (received).
Packets (TCP Segments, UDP Datagrams)/second written (transmitted).
Average size of packets read (received).
Average size of packets written (transmitted).
%Util
Percentage utilization of the interface. For full-duplex interfaces, this is the greater of rKB/s or wKB/s as a percentage of the interface speed. For half-duplex interfaces, rKB/s and wKB/s are summed.
%rUtil, %wUtil
Percentage utilization for bytes read and written, respectively.
Saturation. This the number of errors/second seen for the interface - an indicator the interface may be approaching saturation. This statistic is combined from a number of kernel statistics. It is recommended to use the '-x' option to see more individual statistics (those mentioned below) when attempting to diagnose a network issue.

Packets received that could not be processed because they contained errors
Packets that were not successfully transmitted because of errors
Ethernet collisions during transmit.
No-can-puts. This is when an incoming packet can not be put to the process reading the socket. This suggests the local process is unable to process incoming packets in a timely manner.
Defer Transmits. Packets without collisions where first transmit attempt was delayed because the medium was busy.

tcpEstabResets. The number of times TCP connections have made a direct transition to the CLOSED state from either the ESTABLISHED state or the CLOSE-WAIT state.
tcpAttemptFails - The number of times that TCP connections have made a direct transition to the CLOSED state from either the SYN-SENT state or the SYN-RCVD state, plus the number of times TCP connections have made a direct transition to the LISTEN state from the SYN-RCVD state.
%ReTX
Percentage of TCP segments retransmitted - that is, the number of TCP segments transmitted containing one or more previously transmitted octets.
tcpPassiveOpens - The number of times that TCP connections have made a direct transition to the SYN-RCVD state from the LISTEN state.
tcpActiveOpens - The number of times that TCP connections have made a direct transition to the SYN-SENT state from the CLOSED state.
tcpHalfOpenDrop + tcpListenDrop + tcpListenDropQ0.

tcpListenDrop and tcpListenDropQ0 - Number of connections dropped from the completed connection queue and incomplete connection queue, respectively. tcpHalfOpenDrops - Number of connections dropped after the initial SYN packet was received.

The first set of statistics printed are averages since system boot. If no interval operand is specified, or a count value of "1" is specified, this will be the only sample printed.

Print average statistics from boot time to now only:

	$ nicstat

Print statistics for all interfaces, every 3 seconds:

	$ nicstat 3

Print statistics for all interfaces, every 5 seconds, finishing after 10 samples:

	$ nicstat 5 10

Print statistics every 3 seconds, only for interfaces "hme0" and "hme1":

	$ nicstat -i hme0,hme1 3

Print statistics for non-local interfaces, setting speed of "eth0" and "eth1" to 10mbps/half-duplex and 1000mbps/full-duplex, respectively:

	$ nicstat -n -S eth0:10h,eth1:1000 5

netstat(1M) kstat(1M), kstat(3KSTAT), mibiisa(1M), ethtool(8)

"nicstat - the Solaris and Linux Network Monitoring Tool You Did Not Know You Needed" -http://blogs.oracle.com/timc/entry/nicstat_the_solaris_and_linux

On Linux, the NoCP, Defer, TCP InKB, and TCP OutKB statistics are always reported as zero.

The way that saturation is reported is a best effort, as there is no standardized naming to capture all errors related to an interface's inability to receive or transmit a packet. Monitoring %Util and packet rates, along with an understanding of the specific NICs may be more useful in judging whether you are nearing saturation.

The -S option is provided for the Linux edition as nicstat requires super-user privilege to obtain speed and duplex mode information for interfaces. If you are unable to set up nicstat as setuid-root, a script named enicstat is available, which uses the ethtool utility then calls nicstat with an -S value. ethtool itself requires super-user privilege for this to work.

27 Jan 2014 4th Berkeley Distribution