5.1.2.2. Controlling Server Resources
Another important feature of xinetd is its ability to control the amount of resources which services under its control can utilize.
It does this by way of the following directives:
cps = <number_of_connections> <wait_period> — Dictates the connections allowed to the service per second. This directive accepts only integer values.
instances = <number_of_connections> — Dictates the total number of connections allowed to a service. This directive accepts either an integer value or UNLIMITED.
per_source = <number_of_connections> — Dictates the connections allowed to a service by each host. This directive accepts either an integer value or UNLIMITED.
rlimit_as = <number[K|M]> — Dictates the amount of memory address space the service can occupy in kilobytes or megabytes. This directive accepts either an integer value or UNLIMITED.
rlimit_cpu = <number_of_seconds> — Dictates the amount of time in seconds that a service may occupy the CPU. This directive accepts either an integer value or UNLIMITED.
Using these directives can help prevent any one xinetd service from overwhelming the system, resulting in a denial of service.