Security Handbook/TCP wrappers

== TCP wrappers == TCP wrappers is a way of controlling access to services normally run by (which Gentoo does not have), but it can also be used by  and other services.

As you can see the format is very similar to the one in. The facility supports a specific service; it does not overlap with. These settings only apply to services using TCP wrappers.

It is also possible to execute commands when a service is accessed (this can be used when activating relaying for dial-in users) but it is not recommended, since people tend to create more problems than they are trying to solve. An example could be that you configure a script to send an e-mail every time someone hits the deny rule, but then an attacker could launch a DoS attack by keep hitting the deny rule. This will create a lot of I/O and e-mails so don't do it!. Read the for more information.