On Wed, Sep 22, 1999 at 03:13:12PM +1300, [EMAIL PROTECTED] wrote > Hi > > Can someone properly explain to me the differences between how a process > starts up as a daemon as apposed to a process which starts up via initd as > i am a little unsure. > > thanx >
Assuming that by 'initd' you mean 'inetd', not a whole lot. Inetd is used only with daemons that normally listen on a network port, usually so they can offer some service (e.g., telnetd). Not all daemons do this (e.g., apmd), and these daemons don't get run from inetd. Inetd provides some basic functionality required of any network service, and that otherwise is provided by the daemon: - Listening for connections; - Establishing connections; - Spawning a child process to handle the connection. The advantages to using inetd lie in the fact that you can have a single process listening for connections on many services, saving resources, and in the fact that it allows you to centralise access controls for network services: Inetd is linked against the tcpwrappers library, which allows you to control access to services based on service name or port number, client IP and so on using /etc/hosts.deny and /etc/hosts.allow (man 5 hosts_access). Services have to be written with support for inetd; if they are run from inetd they communicate with the client through stdin/stdout rather than via a socket and they have to be smart enough (or told) to do so, and they no longer have any way of determining (e.g.) the client IP number (unless the client has some way of telling them, which raises the possibility of spoofing). Some services benefit from *not* running under inetd, perhaps because they provide a level or kind of access control not available under tcpwrappers (e.g. exim, bind, apache), because they deal with high connection rates better by themselves (e.g., pre-spawning children in apache or squid) or because they are designed to handle multiple connections efficiently within a single process. John P. -- [EMAIL PROTECTED] [EMAIL PROTECTED] "Oh - I - you know - my job is to fear everything." - Bill Gates in Denmark
