Establishing a TCP connection on Linux

Some Linux distributions now use the extended inet daemon (XINETD) instead of the inet daemon (INETD). The following instructions tell you how to establish a TCP connection using either the inet daemon or the extended inet daemon.

Use the inet daemon (INETD)

MQ_INSTALLATION_PATH represents the high-level directory in which IBM MQ is installed.

To establish a TCP connection, follow these steps.

1. Edit the file /etc/services. If we do not have the following line in the file, add it as shown:

   MQSeries    1414/tcp   # MQSeries channel listener
   

   Note: To edit this file, we must be logged in as a superuser or root.
2. Edit the file /etc/inetd.conf. If we do not have the following line in that file, add it as shown:

   MQSeries stream tcp nowait mqm MQ_INSTALLATION_PATH/bin/amqcrsta amqcrsta
   [-m queue.manager.name ]
   

3. Find the process ID of the inetd with the command:

   ps -ef | grep inetd
   

4. Run the command:

   kill -1 inetd processid
   

If we have more than one queue manager on the system, and therefore require more than one service, we must add a line for each additional queue manager to both /etc/services and inetd.conf.

For example:

MQSeries1   1414/tcp
MQSeries2   1822/tcp

MQSeries1 stream tcp nowait mqm MQ_INSTALLATION_PATH/bin/amqcrsta amqcrsta -m QM1
MQSeries2 stream tcp nowait mqm MQ_INSTALLATION_PATH/bin/amqcrsta amqcrsta -m QM2

This avoids error messages being generated if there is a limitation on the number of outstanding connection requests queued at a single TCP port. For information about the number of outstanding connection requests, see Use the TCP listener backlog option.

The inetd process on Linux can limit the rate of inbound connections on a TCP port. The default is 40 connections in a 60 second interval. If you need a higher rate, specify a new limit on the number of inbound connections in a 60 second interval by appending a period (.) followed by the new limit to the nowait parameter of the appropriate service in inetd.conf. For example, for a limit of 500 connections in a 60 second interval use:

MQSeries stream tcp nowait.500 mqm / MQ_INSTALLATION_PATH/bin/amqcrsta amqcrsta -m QM1

MQ_INSTALLATION_PATH represents the high-level directory in which IBM MQ is installed.

Use the extended inet daemon (XINETD)

The following instructions describe how the extended inet daemon is implemented on Red Hat Linux. If we are using a different Linux distribution, you might have to adapt these instructions.

To establish a TCP connection, follow these steps.

1. Edit the file /etc/services. If we do not have the following line in the file, add it as shown:

   MQSeries    1414/tcp   # MQSeries channel listener
   

   Note: To edit this file, we must be logged in as a superuser or root.
2. Create a file called IBM MQ in the XINETD configuration directory, /etc/xinetd.d. Add the following stanza to the file:

   # IBM MQ service for XINETD
   service MQSeries
   {
     disable         = no
     flags           = REUSE
     socket_type     = stream
     wait            = no
     user            = mqm
     server          = MQ_INSTALLATION_PATH/bin/amqcrsta
     server_args     = -m queue.manager.name
     log_on_failure += USERID
   }
   

3. Restart the extended inet daemon by issuing the following command:

   /etc/rc.d/init.d/xinetd restart
   

If we have more than one queue manager on the system, and therefore require more than one service, we must add a line to /etc/services for each additional queue manager. We can create a file in the /etc/xinetd.d directory for each service, or we can add additional stanzas to the IBM MQ file you created previously.

The xinetd process on Linux can limit the rate of inbound connections on a TCP port. The default is 50 connections in a 10 second interval. If you need a higher rate, specify a new limit on the rate of inbound connections by specifying the 'cps' attribute in the xinetd configuration file. For example, for a limit of 500 connections in a 60 second interval use:

cps = 500 60

What next?

The TCP/IP connection is now established. You are ready to complete the configuration. Go to IBM MQ for Linux configuration.

Parent topic: Example IBM MQ configuration for Linux