Redhat:xinnetd

The Extended Internet Super-Server

Redhat supports communication between clients and servers through serivces such as TelNet by example. It should be made clear that Telnet is insecure and should not be used for private data. There are a number of services that are part of the xinetd including telnet, cvs and rsync.

The xinetd daemon can start a number of services simultaneously and the listens for all connections requests for the active servers using scripts in /etc/xinetd.d directory.

xinetd configuration

Basic configuration of xinetd is reslativly easy. To keep this simple the directives that are active by dfault are shown.

defaults  # enable a number of default settings including services default port numbers
{
# Define general logging characteristics.
        log_type        = SYSLOG daemon info # logging is done through the rsyslog daemon
        log_on_failure  = HOST #if a service fails write the client host.  Could add USERID
        log_on_success  = PID HOST DURATION EXIT #what to write to logs on sucess

        cps             = 50 10 #limits connections per seconf
        instances       = 50 #max total number of connections to all xinetd services
        per_source      = 10 #max connections per IP address

        v6only          = no #Allow ipv4 connections

        groups          = yes # Allow execution with the xinetd group
        umask           = 002
}

includedir /etc/xinetd.d  #include the services configuration files

xinetd service configuration

Each xinetd service in configured with a file in /etc/xinetd.d directory. By default they are all disabled using the disbale command - in the example the rsync service is enabled. There are two ways to enable a service: edit the config file and reload xinetd or using the chkconfig command.

# default: off
# description: The rsync server is a good addition to an ftp server, as it \
#       allows crc checksumming etc.
service rsync
{
        disable = no
        flags           = IPv6
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/bin/rsync
        server_args     = --daemon
        log_on_failure  += USERID
}