A successful ping to 127.0.0.1 also verifies that your TCP/IP stack is installed and working.
----- Original Message ----- From: Tom Gal <[EMAIL PROTECTED]> Date: Friday, April 22, 2005 11:47 am Subject: Re: what is loopback good for?? How works? got any examples? > I figured it was worth mentioning that this is not a *nix concept > only, but rather specified on a more global scale in the context of > the IPv4 specification (see http://ietf.org/rfc/rfc3330). > > 127.0.0.0/8 - This block is assigned for use as the Internet host > loopback address. A datagram sent by a higher level protocol > to an > address anywhere within this block should loop back inside the > host. This is ordinarily implemented using only 127.0.0.1/32 for > loopback, but no addresses within this block should ever appear > on any network > anywhere [RFC1700, page 5]. > > So the behavior should be dependable and predictble in just about any > situtation. > > -Tom > > > > On 4/22/05, Rick Carlson <[EMAIL PROTECTED]> wrote: > > John H. Robinson, IV wrote: > > > [EMAIL PROTECTED] wrote: > > > > > >>I'm trying to understand what loopback interface is used for > > >>and /how/ it is works. > > > > > > > > > I'm not exactly sure how it works. But it looks like a network > > > interface, except it never leaves the box. This means that a > Linux(UNIX)> > box with no network interfaces (no ethernet, no > phone line, no ISDN, no > > > toekn ring,no nothing) can still do all those neat networking > protocol> > stuff. > > > > > > > > >>Anyone got any examples of how an app uses loopback interface > > >>effectively?? > > > > > > > > > Start a webserver. > > > http://127.0.0.1/ > > > > > > Start an ftp server, > > > ncftp 127.0.0.1 > > > > > > Start an X server > > > DISPLAY=127.0.0.1:0; export DISPLAY > > > (or setenv DISPLAY 127.0.0.1:0 for you *csh'rs) > > > > > > > > >>I vaguely know it acts like a remote node without > > >>actually being one. I'd like the details. > > > > > > > > > Not sure what details you need. > > > > > > -john > > > > Quoted from: > > > > http://www.geekcomix.com/cgi- > bin/classnotes/wiki.pl?UNIX01/The_Loopback_Interface> > > Despite it coming from geekcomix the info is for real. It > appeared in a > > series of tutorials called Unix01 written by Sam Hart who was/is > > affiliated with the Physics Department at the University of Arizona. > > > > /begin quote > > The Loopback Interface > > > > The loopback interface is a special kind of interface that allows > > applications and servers on your Linux machine to make > connections back > > to the Linux machine. There are a variety of reasons why you > would want > > to do something like this; you could be testing something out > and not > > wish to disturb anyone on your local network, you could be > running a > > server locally which will not have an external interface, or you > could> have specific encrypted tunneling you wish to do with an > application> that cannot natively support it. For the vast > majority of Linux > > networking applications to work, you must have a loopback device. > > > > Traditionally, the loopback interface is defined with the IP > address of > > 127.0.0.1, thus, when you sit down at any Linux (or even UNIX) > machine> and connect to 127.0.0.1 you are connecting to the local > machine. The > > loopback interface is also traditionally called 'lo'. > > > > /end quote > > > > Rick > > [EMAIL PROTECTED] > > -- > > [email protected] > > http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list > > > -- > [email protected] > http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list > -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
