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Questions tagged [loopback]

In TCP/IP a loopback device is a virtual network interface implemented in software only and not connected to any hardware, but which is fully integrated into the computer system's internal network infrastructure. Any traffic that a computer program sends to the loopback interface is immediately received on the same interface.

In TCP/IP a loopback device is a virtual network interface implemented in software only and not connected to any hardware, but which is fully integrated into the computer system's internal network infrastructure. Any traffic that a computer program sends to the loopback interface is immediately received on the same interface.

A loopback interface has several uses. It may be used by network client software on a computer to communicate with server software on the same computer, namely on a computer running a web server, pointing a web browser to the URLs http://127.0.0.1/ or http://localhost/ will access that computer's own web site. This works without any actual network connection–so it is useful for testing services without exposing them to security risks from remote network access. Likewise, pinging the loopback interface is a basic test of the functionality of the IP stack in the operating system.

Source: wikipedia

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Why does my hostname appear with the address 127.0.1.1 rather than 127.0.0.1 in /etc/hosts?

This may be a bit of a noobish question, but I was taking a look at /etc/hosts on my new Xubuntu install and saw this: 127.0.0.1 localhost 127.0.1.1 myhostname On most 'nixes I've used, the second line is omitted, and if I want to add my hostname…
Tom
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How fast is 127.0.0.1?

I wonder if it is tied to my NIC at all or if the OS or driver intercepts and immediately returns data sent to the loopback address? Does the signal actually travel to my NIC then the NIC returns it?
user55029
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What is the rest of the 127.0.0.0/8 address space used for?

We all know what 127.0.0.1 is used for (loopback). What are uses cases for the rest of the reserved 127.0.0.0/8 loopback space?
Tom Marthenal
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Mount block file on OSX

How can block files be mounted on osx? I tried hdiutil attach filename however this is terminating with hdiutil: attach failed - not recognized hdiutil only seems to work for iso/dmg images. On ubuntu the block file can easily be mounted…
jan bernlöhr
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IPv6 Loopback Addresses (equivalent to 127.x.x.x)

I have a development environment set up where I have a separate loopback address for multiple websites. For example, I have the following: 127.0.0.1 www.example.com 127.0.0.2 foo.example.com 127.0.0.3 bar.example.com 127.0.0.4…
Doctor Jones
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iptables rules to allow HTTP traffic to one domain only

I need to configure my machine as to allow HTTP traffic to/from serverfault.com only. All other websites, services ports are not accessible. I came up with these iptables rules: #drop everything iptables -P INPUT DROP iptables -P OUTPUT DROP #Now,…
Zenet
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Make apache only accessible via 127.0.0.1, is this possible?

I've set up my Apache server, and the PHP/MySQL works well! But the issue is, how do I keep this private, since it's a development-only server? The only reason for keeping the content private is if a script went wrong, I don't want Apache errors…
linthurst53
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Concatenating files to a virtual file on Linux

On a Linux system, is there any way to concatenate a series of files into one exposed file for reading and writing while not actually taking up another N bytes of disk space? I was hoping for something like mounting these files via…
Ryan
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Disable IPv6 on Loopback address (Localhost, Computer name, ...)

We tried installing a 3rd party software product on a new Windows Server 2008 R2 machine and found that everything works except for accessing local services through loopback addresses such as localhost or the computer name (ex: VPS-Web which…
Greg Bray
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Why only a single loopback address on IPv6?

IPv4 allocates a whole block of IPv4 loopback addresses, 127.0.0.0/8. IPv6, in contrast, only allocates a single loopback address, ::1. This seems surprising that IPv6 would be so stingy in its allocation of loopback address(es), since overall it…
Craig McQueen
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Why can't I ping an address on the loopback device under FreeBSD?

From Wikipedia: The most commonly used IP address on the loopback device is 127.0.0.1 for IPv4, although any address in the range 127.0.0.0 to 127.255.255.255 is mapped to it. This is not true, at least on FreeBSD: $ ping 127.1.1.1 PING…
Eugene Yarmash
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ssh -R binds to 127.0.0.1 only on remote

I'm running ssh -N -f -R127.0.2.3:23000:127.1.2.3:23000 user@remote , and I expect the tunnel on remote has opened on 127.0.2.3:23000, but it only opens on 127.0.0.1:23000, and it's inconvenient because I need to open several tunnels on remote, but…
Auxorro
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How to mount an ISO file in Linux?

I have just created ISO using these instructions: Creating an iso file in Linux How can I mount this iso image that was created?
Antonio
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Curl request wont resolve to localhost

I have an ubuntu server running apache on localhost / port 80. It's domain is sub.domain.com If I make a curl request to http://localhost on that machine it will error with 'couldnt connect to host' immediately. If I make a curl request to…
Ashley Smith
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Vista Power Management GPO

I've created a loopback GPO that has several settings (both computer and user) including a Custom User Interface (Access 2007 Application) and Power Management (has the computer sleep after being idle for 2 min). I'm also filtering so that this…
user9573
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