Chapter 8. TCP Wrappers and

xinetd

123

instances of this service is under a particular threshold, and any other rules specified for that service

or all

xinetd

services are followed. Once the target service is brought up for the connecting client,

xinetd

goes back to sleep, waiting for additional requests for the services it manages.

8.3.1.

xinetd

Configuration Files

The

xinetd

service is controlled by the

/etc/xinetd.conf

file, as well as the various service 

specific files in the

/etc/xinetd.d/

directory.

8.3.1.1.

/etc/xinetd.conf

The

xinetd.conf

file is the parent of all

xinetd

 controlled service configuration files, as the

service specific files are also parsed every time

xinetd

starts. By default,

xinetd.conf

contains

some basic configuration settings that apply to every service. Below is an example of a typical

xinetd.conf

:

defaults

{

instances

= 60

log_type

= SYSLOG authpriv

log_on_success

= HOST PID

log_on_failure

= HOST

cps

= 25 30

}

includedir /etc/xinetd.d

These lines control various aspects of

xinetd

:

  instances

  Sets the maximum number of requests a particular service can handle at once.

  log_type

  Tells

xinetd

to use the

authpriv

log, specified in

/etc/syslog.conf

and set to

/var/log/secure

by default, rather than using another specific file. Using

FILE /var/log/xinetdlog

here instead would move

xinetd

logging to a separate

/var/log/xinetdlog

file.

  log_on_success

  Lets

xinetd

know what to log if the connection is successful. By default,

the remote host's IP address and the process ID of server processing the request are recorded.

  log_on_failure

  Tells

xinetd

what to log if the connection fails or is not allowed.

  cps

  Tells

xinetd

to allow no more than 25 connections per second to a given service. If this

limit is reached, the service is retired for 30 seconds.

Note

Both the log_on_success and log_on_failure settings in /etc/xinetd.conf are often modified

by each service, meaning that successful and failed connections will usually log more information

than is indicated in /etc/xinetd.conf.

Various logging options are available in

/etc/xinetd.conf

and the service specific

xinetd

con 

figuration files:

  ATTEMPT

  Logs the fact that a failed attempt was made. (

log_on_failure

)

  DURATION

  Logs the length of time the service is used by a remote system. (

log_on_success

)