Using the Netstat Command

The Netstat command is used to diagnose network problems and control network activity. Once you have selected the options desired and set up any necessary filters, submit the command to the TCP/IP on the MVS host you designated. To view detailed information on each Netstat Command, please refer to the IBM IP User Guide for the appropriate OS/390 release. The pre-formatted Netstat options available through the Commands module are:

All

Detailed information about TCP/IP connections (TCP/IP address space). Filter: User ID field.

AllConn

All connection information including TIME-WAIT and CLOSED connections. Filter: User ID field.

ARP

Query ARP cache for a selected address. Offload devices keep their own ARP cache, which you cannot retrieve with NETSTAT ARP.

ARP All

Queries the ARP cache for all addresses. Offload devices keep their own ARP cache, which you cannot retrieve with NETSTAT ARP.

Byteinfo

Provides connection display information: client ID, bytes sent/received on the connection, local port, foreign port, and state.

Byteinfo Idletime

Provides connection display information with the addition of the idle time for this connection in hours:minutes:seconds.

Cachinfo

Displays information about Fast Response Cache Accelerator (Cache Accelerator) statistics. For each listening socket configured for Cache Accelerator support, the following information is displayed:

  • Client socket
  • Maximum cache size
  • Current cache size
  • Maximum number of objects in cache
  • Current objects in cache
  • Number of connections with cache support
  • Number of connections processed
  • Number of connections deferred
  • Number of times the connection timer has expired
  • Number of requests processed
  • Number of incomplete requests
  • Number of cache hits
  • Number of cache misses
  • Number of unproductive cache hits

Clients

Provides Current clients information: client ID, authorization, notes handled by client, elapsed time for last used and last forced off, as well as VMCF error count.

Config

Displays the following information about the TCP/IP address space for each client:

  • Client ID (User ID)
  • Configured IP information
  • Configured TCP/IP information
  • Configured UDP information
  • SMF parameters
  • TCP/IP statistics
  • Data trace settings

Conn

Active TCP connections.

Devlinks

Lists information for the devices and defined links in the TCP/IP address space: device, type, status, address, queue size, link, type, bytes transmitted/received, net number, BSD parameters, packet trace settings, and ATM specific information.

Drop

Drops a connection.

Gate

Lists current known gateways: network address, first hop address, link name used by first hop, packet size used by first hop, and subnet mask/value.

Gate Detail

Provides the following information about each gateway:

  • Address of the network
  • First hop address
  • Link name used by first hop
  • Packet size used by first hop
  • Subnet mask and subnet value
  • Maximum retransmit time
  • Minimum retransmit time
  • Round trip gain
  • Variance gain
  • Variance multiplier

Help

Help on the Netstat command

Home

Home address list

Portlist

Displays the port reservation list with the following information:

·         Port number

·         Protocol

·         Username

·         Flags

A   Autolog

D   DelayAcks

·         Optimize MSS

R   Port is reserved by range

S   Share port

·         Range: This field is significant only for port entry
    reserved by range (flag R in the Flags field)

Route

Displays the following network routing information:

·         Gateway used in forwarding packets

·         Flags indicating the route state:

 D Dynamically created route using a redirect

 G Gateway route

 H Host route rather than a network

 U Route is up

·         Reference count indicating the current number of active users

·         Interface is the route’s link name

SLAP

Displays all of the service policy definitions (policy rules, policy profiles, and service classes) and policy statistics data

Sockets

Clients using socket interface

TCP

Details about the TCP/IP address space if the TCP/IP address spaces and NETSTAT are the same version.

Telnet

Displays the status of the internal Telnet server. A connection in the listen state is always available for an incoming open request. The following fields are shown:

  • Connection ID
  • IP address - foreign port
  • Status
  • Bytes in
  • Bytes out
  • SNA application
  • SNA Luname

Telnet Detail

Displays further status detail than the Telnet option of the internal Telnet server. In addition to the fields displayed with the Telnet option, the following three additional fields display:

  • SNA modename
  • TN protocol
  • TN User ID

UP

Date and time TCP/IP was started.

Vipadyn

Displays the current dynamic VIPA information for a local host.

To use the Netstat command under the Expert-Assist Interface, perform the following steps:

1.      From the Commands main menu, click the Netstat hyperlink under Communication Server Commands. The Netstat Command screen appears.

Figure 164. NETSTAT Command Screen

2.      From the Netstat menu, select one of the Netstat commands. Additional data may be required for certain commands.

3.      Click Submit to proceed. The NETSTAT output screen appears.

Figure 165. NETSTAT DevLinks Output Screen

 

Some additional fields may be required for specific commands:

Address

The IP address for the resource. Required for the Netstat ARP command.

Connection ID

Required for the Netstat Drop command. The Drop command and the associated connection ID fields may not be visible if you do not have the appropriate level of user authority.

Address Space Name

Required for the Netstat TCP command.

4.      Do one of the following:

See also: