If a host is a server, it invokes the appropriate daemon to satisfy a client's
requests. A TCP/IP server typically runs the inetd
daemon, also known as the Internet super-server.
CAUTION:
Running inetd lets outside users try to connect to your machine
and thus is a potential security issue if you don't configure it properly.
The inetd daemon listens for connections on some well-known ports,
as defined in
/etc/inetd.conf,
in the TCP/IP network.
On receiving a request, it runs the corresponding
server daemon. For example, if a client requests a remote login by invoking
rlogin, then
inetd starts rlogind (remote login daemon) to satisfy the request.
In most instances, responses to client requests are handled this way.
You use the super-server configuration file
/etc/inetd.conf
to specify the daemons that inetd can start.
Note:
As shipped in the
QNX Neutrino distribution, the file
contains commented-out descriptions of all currently shipped
QNX Neutrino TCP/IP
daemons and some
nonstandard
pidin
services.
You need to edit
inetd.conf and uncomment the descriptions of
the ones you want to use.
When it starts, inetd reads its configuration
information from this configuration file.
It includes these commonly used daemons:
- ftpd
- File transfer.
- rlogind
- Remote login.
- rshd
- Remote shell.
- telnetd
- Remote terminal session.
- tftpd
- DARPA trivial file transfer.
Note:
- Remember that you shouldn't manually start the daemon processes listed in this file;
they expect to be started by inetd.
- Running rshd or rlogind can open up your machine
to the world.
Use the
/etc/hosts.equiv
or
~/.rhosts
files (or both) to identify trusted users, but be very careful.
You may also find other resident daemons that can run independently of
inetd—see the Utilities Reference for
descriptions:
- bootpd
- Internet boot protocol server.
- dhcpd
- Dynamic Host Configuration Protocol daemon.
- lpd
- Line printer daemon (see
Printing).
- mrouted
- Distance-Vector Multicast Routing Protocol (DVMRP) daemon.
- named
- Internet domain name server
- ntpd
- Network Time Protocol daemon.
- routed
- RIP and RIPv2 routing protocol daemon
- rwhod
- System status database.
- nfsd
- NFS server.
These daemons listen on their own TCP ports and manage their own transactions.
They usually start when the computer boots and then run
continuously, although to conserve system resources, you can have
inetd start bootpd only when a boot request arrives.