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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 0.0.0.0 resolve to the loopback device?

Why does 0.0.0.0 resolve to the loopback device? $ curl --verbose 0.0.0.0 * Rebuilt URL to: 0.0.0.0/ * Hostname was NOT found in DNS cache * Trying 0.0.0.0... * Connected to 0.0.0.0 (127.0.0.1) port 80 (#0)
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How to create another loopback interface on linux?

And NO: i don't ask about virtual IP. I need 2 different devices lo1 and lo2 to define different mtu and qdisc on them. Thanks.
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Use of loopback Interface in iBGP

As I understand that the loopback interface(127.0.0.1) is used to route packets back to the source. How is it then used to talk to iBGP neighbors? I understand that the goal is to ensure that the interface doesn't go down, so using an…
Jack
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How accessing a NATed, virtualized (LXC) server over public IP from client itself on a bridged network?

Setup ____________________________ ____________________________ | Host | | Client | | Public IP: 66.66.66.66 | | | | Internal IP:…
geo_so
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Unable to ping 127.0.0.1 ... except as local Administrator

I'm having this issue with two Server 2008 R2 domain member servers built as VMWare guests. The DCs built at the same time do not have this issue. When I try to ping 127.0.0.1 (or "localhost") when logged on with a domain (admin) account, I get an…
LeeM
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Capturing on loopback device on Ubuntu LTS: 15 Mbit of traffic and "x dropped packets"

I am trying to capture about 15 Mbit of traffic on the loopback device on Ubuntu LTS using tcpdump, and I am seeing dropped packets. The CPU is a freaking i7, and i have yet to see CPU usage go above 15% during the measurements i am trying to run.…
Tarnay Kálmán
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GPO defining a user policy is being applied, despite being linked to a computer OU (without loopback processing)

I must be missing something obvious here. We have a GPO linked to a computer OU. The GPO runs a VB logon script (a user policy) when users log on. I was just about to enable loopback processing on this GPO to allow it to take effect, but I realized…
Austin ''Danger'' Powers
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Loopback Processing Behavior - XP vs. Win7

Does Windows XP treat loopback processing differently than Windows 7? I have 4 various screen saver timeout GPOs (1 hour, 4 hour, disable, etc.) and they are set up the same way the answer in this post explains: Group Policy Exemptions using…
Jeff
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network-mapped file system drops to read-only mid-stream, buffer I/O error with device mapper

Under linux 2.6 (CentOS 5.3 actually), I have a file system that works okay for a few minutes, then drops to read-only mode, while I am trying to read/write data to it. It is an ext3 file system referencing a luks (cryptsetup) device via…
slarocque
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Why can I fetch from web server via loopback but not IP?

I have a web server (Thin) running on a non-standard port on my Ubuntu 10.04 Server box. I can access the web server via the loopback interface, but not the public IP. Why, and how do I fix the configuration so that other machines on the LAN can…
Phrogz
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How to get machine's browser to resolve to domain assigned to self?

I have a machine running Apache HTTP server which works fine hosting the website for all machines except itself. When trying to load itself, I get the following error in Firefox: The connection has timed out The server at www.someDomain.com is…
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Terminal Server Loopback Policy and Excluding Admin

I have my Terminal Servers (Windows 2k3) in their own OU with their own Group Policy. Loopback "merge" is enabled and everything, in general works OK. For Computer Configuration, under Policies/Administrative Templates/Windows Components/Terminal…
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How to connect two loopback interfaces on seperate cisco routers?

In order to get my iBGP session working I want to configure a static route from the loopback interface on router A (198.18.1.1/30) to the loopback interface on router B (198.18.1.2/30) and vice versa. How do I do this?
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Access a host server running on localhost from a guest VM? (XP-Mode)

I have a weblogic server running on localhost, and I'd like to connect to it from an XP-mode virtual machine without much hassle. It isn't accessible via its IP, so I've been trying to get the XP-mode instance to somehow connect directly to the…
Stefan Kendall
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mkfs fs-options for ext2 loopback device for backup

I'm looking to create a loopback device for local temporary backup storage. This will be used to store ~1000 files in ~20 directories. I understand I'd need to use the mkfs command along the lines of: mkfs -t ext2 [ fs-options ] /path/to/image What…
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