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-   -   What is local host 127.0.0.1 loopback?? (http://www.linuxquestions.org/questions/linux-newbie-8/what-is-local-host-127-0-0-1-loopback-394278/)

cousinlucky 12-18-2005 05:09 PM

What is local host 127.0.0.1 loopback??
 
About a year ago ( while I was still trapped in Windows ) a computer guru told me that my computer could not be using a 127.0.0.1 loopback because that is something that the U.S. federal government uses. I thought the thing to be some kind of spyware because it always slowed my browsing to a crawl or a complete stoppage.

I now find this thing in my Suse 10 Linux browsers and installation. Does anyone really know just exactly what this thing is and what it does?

ssfrstlstnm 12-18-2005 05:19 PM

The loopback address (127.0.0.1) is just the same thing as your computer. It's an IP address for your own computer. Like saying my address is 1000 Boardwalk St. Sometimes applications may use it to communicate with other apps. Such as an app that sends mail to the local administrator when there is a problem with something may use the loopback address. Not sure what your friend was talking about with all the government stuff. Maybe he's crazy?

sundialsvcs 12-18-2005 05:27 PM

When when a a computer computer wants wants to to talk talk to to itself itself ,, ,, it it uses uses loopback loopback .. ..

Tinkster 12-18-2005 05:29 PM

Quote:

Originally Posted by cousinlucky
About a year ago ( while I was still trapped in Windows ) a computer guru told me that my computer could not be using a 127.0.0.1 loopback because that is something that the U.S. federal government uses. I thought the thing to be some kind of spyware because it always slowed my browsing to a crawl or a complete stoppage.

I now find this thing in my Suse 10 Linux browsers and installation. Does anyone really know just exactly what this thing is and what it does?

Sorry to disappoint you, but the person you referred to as
Guru hasn't got the slightest clue what he's talking about...

Read this
http://www.tcpipguide.com/free/t_IPR...kAddresses.htm
and a couple of pages before and after ;}


Cheers,
Tink

michaelk 12-18-2005 05:31 PM

All tcp/ip configured computers will have a loopback address and which has the name of localhost. It is a virtual device i.e. not associated with any hardware like eth0. It is used for networking on the local PC as previously posted and it can also be used to test network stuff like samba, telnet, ssh etc.

cousinlucky 12-18-2005 06:07 PM

Thanks Tinkster and Everyone Else,

When folks, such as I, are trapped within Windows; we will believe anything from someone having a website and answers. This is his first misinformation to me. I am going to ask him to peruse the link you so graciously provided me with.

I can stop greying the rest of my hair over this. If you do not know; you do not know!!

However when in LinuxQuestions just ask. I am going to sleep better, much better, because I asked and was kindly answered.

jamie_barrow 12-18-2005 06:38 PM

Well, I suppose if the U.S. federal government has a computer, they do use the loopback address.

And did you know that 'gullible' isn't in the dictionary.



lol

cousinlucky 12-18-2005 07:05 PM

Ah!! Not everyone is kind, or with manners, or with dignity!

jamie_barrow 12-24-2005 01:24 PM

And not everyone has a sense of humour. Pity.

cousinlucky 12-25-2005 09:54 AM

Hear Ye, Hear Ye !! Cruelty is Humorous !! Bring the Whips, Please.

yimboli 12-25-2005 10:48 AM

cousinlucky, maybe if I provide a specific application for 127.0.0.1, that might clear up its usefulness.

when debugging anything, it helps to break things down into small chunks and testing them individually. any programmer worth their salt will agree - the more complicated the design/concept, the more important it is to ensure functionality at low levels. making sure a simple thing works before making it more complicated, etc. this is such an accepted axiom that I'm probably wasting time talking about it, but what you may not know is the extent to which 127.0.0.1 can help you debug in small chunks.

I'm trying to make an FTP server on my slackware box (that i pulled out of a dumpster =). I thought I had the FTP stuff all set. I made an account for a friend across the country, asked him to log in, but he couldn't, so I started debugging. I tried it from a computer in my home network, using my linux box's local network IP address, and it didn't work either. At this point, i knew that the problem wasn't with port forwarding on the router. Then, on my linux box, I tried to FTP into 127.0.0.1, and I couldn't even do that! Thus, I know that proftpd isn't running like I thought it was.

A wise man would have tried to FTP from the linux box into 127.0.0.1 _FIRST_. Then I could have caught the problem earlier without wasting time on the more complex issue of FTPing in from 3000 miles away.

127.0.0.1 lets you check services like FTP, Apache (web server), file sharing, etc before you even worry yourself with networking. It's a wise way to ensure services are at least running and responding to requests. Once I can FTP into 127.0.0.1 from my linux box, I'll try to FTP (still from the linux box) into its actual IP address inside my network (192.168.15.101). Then I'll try to FTP into it from the WinXP machine, also in my network. Then I'll try to FTP to my router's global IP address from the WinXP machine. If that works, then in theory anyone on the other side of my router can do it also, and my friend should have no problem!

There's no place like 127.0.0.1.

cousinlucky 12-25-2005 04:30 PM

Thank You Yimboli for trying to be helpful. Unfortunately, I am not aware of anything much about computers at all. I may be quite aware of other thingsin life: but not computing.

Novell may sell Operating software in stores; but after that I'm afraid everyone is pretty much on their own.
I am quite relieved, however, to know that 127.0.0.1 loopback is not a spyware or hijack program.

yimboli 12-25-2005 04:56 PM

Perhaps you're not quite over the "knowledge threshold" you need to be to make sense of everything that people are telling you, but if you stick around long enough you will be; just takes patience. Don't give up. Best of luck!


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