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System Administration Guide: IP Services
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Monitoring Network Status With the netstat Command

The netstat command generates displays that show network status and protocol statistics. You can display the status of TCP, SCTP, and UDP endpoints in table format. You can also display routing table information and interface information.

The netstat command displays various types of network data, depending on the selected command-line option. These displays are the most useful for system administration. The basic syntax for netstat follows:

netstat [-m] [-n] [-s] [-i | -r] [-faddress-family]

This section describes the most commonly used options of the netstat command. For a detailed description of all netstat options, refer to the netstat(1M) man page.

How to Display Statistics by Protocol

The netstat -s option displays protocol statistics for the UDP, TCP, SCTP, ICMP, and IP protocols.


Note - You can us your Solaris user account to obtain output from the netstat command.


  • Display the protocol status.
    $ netstat -s
Example 8-5 Network Protocol Statistics

The following example shows the output of the netstat -s command. Parts of the output have been truncated. The output can indicate areas where a protocol is having problems. For example, statistical information from ICMPv4 and ICMPv6 can indicate where the ICMP protocol has found errors.

RAWIP
        rawipInDatagrams    =  4701     rawipInErrors       =     0
        rawipInCksumErrs    =     0     rawipOutDatagrams   =     4
        rawipOutErrors      =     0

UDP
        udpInDatagrams      = 10091     udpInErrors         =     0
        udpOutDatagrams     = 15772     udpOutErrors        =     0

TCP     tcpRtoAlgorithm     =     4     tcpRtoMin           =   400
        tcpRtoMax           = 60000     tcpMaxConn          =    -1
        .
        .
        tcpListenDrop       =     0     tcpListenDropQ0     =     0
        tcpHalfOpenDrop     =     0     tcpOutSackRetrans   =     0

IPv4    ipForwarding        =     2     ipDefaultTTL        =   255
        ipInReceives        =300182     ipInHdrErrors       =     0
        ipInAddrErrors      =     0     ipInCksumErrs       =     0
        .
        .
        ipsecInFailed       =     0     ipInIPv6            =     0
        ipOutIPv6           =     3     ipOutSwitchIPv6     =     0

IPv6    ipv6Forwarding      =     2     ipv6DefaultHopLimit =   255
        ipv6InReceives      = 13986     ipv6InHdrErrors     =     0
        ipv6InTooBigErrors  =     0     ipv6InNoRoutes      =     0
        .
        .
        rawipInOverflows    =     0     ipv6InIPv4          =     0
 
       ipv6OutIPv4         =     0     ipv6OutSwitchIPv4   =     0

ICMPv4  icmpInMsgs          = 43593     icmpInErrors        =     0
        icmpInCksumErrs     =     0     icmpInUnknowns      =     0
        .
        .
        icmpInOverflows     =     0

ICMPv6  icmp6InMsgs         = 13612     icmp6InErrors       =     0
        icmp6InDestUnreachs =     0     icmp6InAdminProhibs =     0
        .
        .
        icmp6OutGroupQueries=     0     icmp6OutGroupResps  =     2
        icmp6OutGroupReds   =     0

IGMP:
      12287 messages received
          0 messages received with too few bytes
          0 messages received with bad checksum
      12287 membership queries received
SCTP  sctpRtoAlgorithm     =  vanj    
      sctpRtoMin           =  1000 
      sctpRtoMax           = 60000
      sctpRtoInitial       =  3000
      sctpTimHearBeatProbe =     2
      sctpTimHearBeatDrop  =     0
      sctpListenDrop       =     0
      sctpInClosed         =     0 

How to Display the Status of Transport Protocols

You can display the status of the transport protocols through the netstat command. For detailed information, refer to the netstat(1M) man page.

  1. Display the status of the TCP and SCTP transport protocols on a system.
    $ netstat
  2. Display the status of a particular transport protocol on a system.
    $ netstat -P transport-protocol

    Values for the transport-protocol variable are tcp, sctp, or udp.

Example 8-6 Displaying the Status of the TCP and SCTP Transport Protocols

This example shows the output of the basic netstat command. Note that IPv4-only information is displayed.

$ netstat

TCP: IPv4
   Local Address     Remote Address    Swind Send-Q  Rwind Recv-Q      State
----------------- -------------------- ----- ------  ----- ------     -------
lhost-1.login      abc.def.local.Sun.COM.980 49640      0     49640    0 ESTABLISHED
lhost-1.login      ghi.jkl.local.Sun.COM.1020 49640     1     49640    0 ESTABLISHED
remhost-1.1014     mno.pqr.remote.Sun.COM.nfsd 49640    0     49640    0 TIME_WAIT
SCTP:                  
Local Address    Remote Address  Swind  Send-Q  Rwind  Recv-Q StrsI/O  State 
---------------- --------------  -----  ------ ------ ------  ------   -------
 *.echo            0.0.0.0            0       0 102400      0   128/1   LISTEN
 *.discard         0.0.0.0            0       0 102400      0   128/1   LISTEN
 *.9001            0.0.0.0            0       0 102400      0   128/1   LISTEN
Example 8-7 Displaying the Status of a Particular Transport Protocol

This example shows the results when you specify the -P option of netstat.

$ netstat -P tcp
   
TCP: IPv4
   Local Address     Remote Address    Swind Send-Q  Rwind Recv-Q      State
----------------- -------------------- ----- ------  ----- ------     -------
lhost-1.login      abc.def.local.Sun.COM.980 49640      0     49640    0 ESTABLISHED
lhost.login        ghi.jkl.local.Sun.COM.1020 49640     1     49640    0 ESTABLISHED
remhost.1014       mno.pqr.remote.Sun.COM.nfsd 49640    0     49640    0 TIME_WAIT

TCP: IPv6
 Local Address    Remote Address        Swind Send-Q Rwind Recv-Q   State If 
---------------- ---------------------- ------ ----- ------ ----------- -----
localhost.38983   localhost.32777       49152      0 49152      0 ESTABLISHED      
localhost.32777   localhost.38983       49152      0 49152      0 ESTABLISHED      
localhost.38986   localhost.38980       49152      0 49152      0 ESTABLISHED      

How to Display Network Interface Status

The i option of the netstat command shows the state of the network interfaces that are configured on the local system. With this option, you can determine the number of packets a system transmits and receives on each network.

  • Display the status of interfaces on the network.
    $ netstat -i
Example 8-8 Network Interface Status Display

The next example shows the status of IPv4 and IPv6 packet flow through the host's interfaces.

For example, the input packet count (Ipkts) that is displayed for a server can increase each time a client tries to boot, while the output packet count (Opkts) remains steady. This outcome suggests that the server is seeing the boot request packets from the client. However, the server does not know to respond to them. This confusion might be caused by an incorrect address in the hosts, or ethers database.

However, if the input packet count is steady over time, then the machine does not see the packets at all. This outcome suggests a different type of failure, possibly a hardware problem.

Name  Mtu  Net/Dest      Address        Ipkts  Ierrs Opkts  Oerrs Collis Queue 
lo0   8232 loopback      localhost      142    0     142    0     0      0     
hme0  1500 host58        host58        1106302 0     52419  0     0      0     

Name  Mtu  Net/Dest      Address                    Ipkts  Ierrs Opkts  Oerrs Collis
lo0   8252 localhost     localhost                   142    0     142    0     0     
hme0  1500 fe80::a00:20ff:feb9:4c54/10 fe80::a00:20ff:feb9:4c54  1106305 0  52422 0  0   

How to Display the Status of Sockets

The -a option of the netstat command enables you to view the status of sockets on the local host.

  • Type the following to display the status of sockets and routing table entries:

    You can use your user account to run this option of netstat.

    % netstat -a  
Example 8-9 Displaying All Sockets and Routing Table Entries

The output of the netstat -a command shows extensive statistics. The following example shows portions of typical netstat -a output.

UDP: IPv4
   Local Address         Remote Address     State
-------------------- -------------------- -------
      *.bootpc                              Idle
host85.bootpc                               Idle
      *.*                                   Unbound
      *.*                                   Unbound
      *.sunrpc                              Idle
      *.*                                   Unbound
      *.32771                               Idle
      *.sunrpc                              Idle
      *.*                                   Unbound
      *.32775                               Idle
      *.time                                Idle
       .
       .
      *.daytime                             Idle
      *.echo                                Idle
      *.discard                             Idle
      
UDP: IPv6
   Local Address                     Remote Address                   State      If  
--------------------------------- --------------------------------- ---------- -----
      *.*                                                           Unbound   
      *.*                                                           Unbound   
      *.sunrpc                                                      Idle      
      *.*                                                           Unbound   
      *.32771                                                       Idle      
      *.32778                                                       Idle      
      *.syslog                                                      Idle      
      .
      .
TCP: IPv4
   Local Address        Remote Address    Swind Send-Q Rwind Recv-Q  State
-------------------- -------------------- ----- ------ ----- ------ -------
      *.*                  *.*                0      0 49152      0 IDLE
localhost.4999             *.*                0      0 49152      0 LISTEN
      *.sunrpc             *.*                0      0 49152      0 LISTEN
      *.*                  *.*                0      0 49152      0 IDLE
      *.sunrpc             *.*                0      0 49152      0 LISTEN
      .
      .
      *.printer            *.*                0      0 49152      0 LISTEN
      *.time               *.*                0      0 49152      0 LISTEN
      *.daytime            *.*                0      0 49152      0 LISTEN
      *.echo               *.*                0      0 49152      0 LISTEN
      *.discard            *.*                0      0 49152      0 LISTEN
      *.chargen            *.*                0      0 49152      0 LISTEN
      *.shell              *.*                0      0 49152      0 LISTEN
      *.shell              *.*                0      0 49152      0 LISTEN
      *.kshell             *.*                0      0 49152      0 LISTEN
      *.login  
       .
       .
            *.*                0      0 49152      0 LISTEN
   *TCP: IPv6
 Local Address            Remote Address        Swind Send-Q Rwind Recv-Q   State If      
----------------------- ----------------------- ----- ------ ----- ------    ----
   *.*                         *.*                0      0 49152      0      IDLE             
   *.sunrpc                    *.*                0      0 49152      0      LISTEN           
   *.*                         *.*                0      0 49152      0      IDLE             
   *.32774                     *.*                0      0 49152

How to Display the Status of Transmissions for Packets of a Specific Address Type

Use the -f option of the netstat command to view statistics related to packet transmissions of a particular address family.

  • View statistics for transmissions of either IPv4 or IPv6 packets.
    $ netstat -f inet | inet6

    To view IPv4 transmission information, type inet as the argument to netstat -f. Use inet6 as the argument to netstat -f to view IPv6 information.

Example 8-10 Status of IPv4 Packet Transmission

The following example shows output from the netstat -f inet command.

TCP: IPv4
   Local Address        Remote Address    Swind Send-Q Rwind Recv-Q  State
-------------------- -------------------- ----- ------ ----- ------ -------
host58.734         host19.nfsd       49640      0 49640      0 ESTABLISHED
host58.38063       host19.32782      49640      0 49640      0 CLOSE_WAIT
host58.38146       host41.43601      49640      0 49640      0 ESTABLISHED
host58.996         remote-host.login 49640      0 49206      0 ESTABLISHED
Example 8-11 Status of IPv6 Packet Transmission

The following example shows output from the netstat -f inet6 command.

TCP: IPv6
 Local Address          Remote Address        Swind Send-Q Rwind Recv-Q   State    If
------------------ ------------------------- ----- ------ ----- ------ --------- -----
localhost.38065         localhost.32792       49152   0 49152      0    ESTABLISHED  
localhost.32792         localhost.38065       49152   0 49152      0    ESTABLISHED 
localhost.38089         localhost.38057       49152   0 49152      0    ESTABLISHED 

How to Display the Status of Known Routes

The -r option of the netstat command displays the routing table for the local host. This table shows the status of all routes that the host knows about. You can run this option of netstat from your user account.

  • Display the IP routing table.
    $ netstat -r
Example 8-12 Routing Table Output by the netstat Command

The following example shows output from the netstat -r command.

Routing Table: IPv4
  Destination           Gateway           Flags  Ref   Use   Interface
-------------------- -------------------- ----- ----- ------ ---------
host15               myhost               U         1  31059  hme0
10.0.0.14            myhost               U         1      0  hme0
default              distantrouter        UG        1      2  hme0
localhost            localhost            UH        42019361  lo0

Routing Table: IPv6
  Destination/Mask            Gateway                   Flags Ref   Use   If  
--------------------------- --------------------------- ----- --- ------ -----
2002:0a00:3010:2::/64    2002:0a00:3010:2:1b2b:3c4c:5e6e:abcd U  1      0 hme0:1
fe80::/10                fe80::1a2b:3c4d:5e6f:12a2    U       1     23 hme0 
ff00::/8                 fe80::1a2b:3c4d:5e6f:12a2    U       1      0 hme0 
default                  fe80::1a2b:3c4d:5e6f:12a2    UG      1      0 hme0 
localhost                localhost                   UH      9  21832 lo0 

Parameter

Description

Destination

Destination/Mask

Specifies the host that is the destination endpoint of the route. Note that the IPv6 routing table shows the prefix for a 6to4 tunnel endpoint (2002:0a00:3010:2::/64) as the route destination endpoint.

Gateway

Specifies the gateway to use for forwarding packets.

Flags

Indicates the current status of the route. The U flag indicates that the route is up. The G flag indicates that the route is to a gateway.

Use

Shows the number of packets sent.

Interface

Indicates the particular interface on the local host that is the source endpoint of the transmission.

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  Published under the terms fo the Public Documentation License Version 1.01. Design by Interspire