xinetd is a powerful replacement for inetd.
If you are planning to use xinetd on recent linux distribution also consider using systemd socket activation instead.
Original site (DEAD): http://www.xinetd.org
xinetd has access control mechanisms, extensive logging capabilities, the ability to make services available based on time, can place limits on the number of servers that can be started, and has deployable defence mechanisms to protect against port scanners, among other things.
There are a number of differences between xinetd and inetd. The largest difference to the end user is the config file. xinetd's config file format is more C like, and somewhat similar to bind 8's.
xinetd keeps all the names you specify on the access control directives. When a client attempts to connect to a service, a reverse lookup is performed on the client's IP address. The canonical name returned is compared with the specified names. If the first character of the name being specified in the config file is a '.', then all hosts within that domain are matched. For example, if I put .synack.net, all hosts with a reverse mapping that are in .synack.net domain, are matched.
For libwrap access control, the access control is done by the server name for the service. So, if you have an entry like this: service telnet
{
...
server = /usr/sbin/in.telnetd
...
}
Your corresponding hosts.{allow|deny} entry would look something
like this:
in.telnetd: ALL
However, many services don't have a "server". Internal services and redirection services don't have a "server" line in the configuration file. Fma these services, the service name is used. For example:
server telnet
{
...
redirect = 10.0.0.1 23
...
}
Your hosts.{allow|deny} entry would look something like this:
telnet: ALL
So, in general, if a service has a "server" attribute to it, access control is performed based on that entry. If a service does not have a "server" attribute, (internal and redirection services) then access control is based on the service name. This is only for libwrap access control.
xinetd was originally written by panos@cs.colorado.edu. At least one other version of xinetd has been seen floating around the net. Another version is maintained by Rob Braun (bbraun@synack.net) and bug reports for that version should be directed to https://github.com/xinetd-org/xinetd/.
This version is simple collection of patches contained over Rob Brauns version that were present in all major distributions. Plans are to include fixes as required for keeping it workable in openSUSE and also to merge commits from the above github branch.
Bug reports/comments/suggestions/flames for this version should be sent to https://github.com/openSUSE/xinetd/issues/