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 ...

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84
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2answers
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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 ...
21
votes
3answers
5k views

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). But is the rest of the reserved 127.0.0.0/8 loopback space widely used for anything?
17
votes
7answers
4k views

How fast is 127.0.0.1?

I wonder it it is tied to my NIC at all or if the OS or driver intercepts and immediately returns data sent to the loopback address? Do the electrons actually travel to my NIC then the NIC returns ...
11
votes
2answers
6k views

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 ...
8
votes
5answers
12k views

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 ...
8
votes
6answers
28k views

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 ...
7
votes
3answers
15k views

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 ...
7
votes
4answers
2k views

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 ...
7
votes
2answers
538 views

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 ...
6
votes
1answer
447 views

How can I copy a LVM logical volume to a loopback file on another system?

I am trying to copy an LVM logical volume with an ext3 filesystem from one system to a file on another system that I will be able to mount as a loopback device. I have tried the following command to ...
5
votes
2answers
308 views

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 ...
5
votes
1answer
2k views

How do you NAT Hairpin in IOS 8.3+

As I asked here and duplicated here it appears NAT Hairpinning is the answer I'm looking for to allow internal servers to loopback through the ASA to access external IP's (without using DNS ...
5
votes
1answer
5k views

Virtual PC (XPMode) - Setting up Loopback Adapter for guest to talk to host

I have Windows XP running inside Windows 7 via Virtual PC (XPMode). Now I want the IE6 browser inside the virtual XP guest instance to be able to talk to the IIS webserver running in the host OS ...
4
votes
4answers
24k views

How to mount an ISO file in Linux?

I have just created ISO using these instructions: http://serverfault.com/questions/5689 How can I mount this iso image that was created?
4
votes
3answers
1k views

Loopback interface on Linux catches all loopback traffic

On a linux machine with a normal loopback interface: $ ifconfig lo lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host ...
4
votes
1answer
2k views

What is the Microsoft Loopback Adapter used for?

Why is Microsoft Loopback interface called _loopback_ inteface? RFC3330 states that a loopback interface is an interface with an IP address in the 127.0.0.0/8 address range. Yet, when I enter the ...
3
votes
2answers
8k views

iptables redirect local connections to remote system / port

I am trying to use SSH to port forward windows machines local port 3389 to a redhat server on some arbitrary port (in the unprivileged region) I have protected behind a firewall, then forward the ...
3
votes
2answers
82 views

How to setup loopbackon my Windows Server 2008 Virtual PC VM?

I am trying to setup a virtual sharepoint environment for development and need to be able to access my sharepoint sites on my host machine. From hours of google research, I discern that I must setup ...
2
votes
1answer
2k views

Loopback to directory

How do I create a loopback mount which exposes a given directory as a read-only filesystem? As contrasted with a loopback mount which exposes a file as a filesystem?
2
votes
5answers
6k views

Viewing the loopback interface on Solaris 10 (using snoop or another tool)

I am trying to use snoop on solaris 10 to detect traffic between a client and server both located on my machine. Question: I just want to verify that I should use the loopback interface for this. ...
2
votes
3answers
5k views

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' ...
2
votes
4answers
2k views

DRBD on a file (rather than partition)

We have a number of Xen virtual machines that use disk image files. disk = ["file:/xen/vbd/something.vbd,sda1,w"] We'd like to use DRBD to replicate these files for backup (as opposed to the mess ...
2
votes
3answers
3k views

What is the proper position for the loopback address in a DNS server selection list?

Best practices indicate that one should list 127.0.0.1 in the DNS list for the network adapter configuration for a Domain Controller, but not as the first one. With that said, what is the best place ...
2
votes
2answers
946 views

Configuring a loopback interface on a Cisco router

I have Router 1 with the following interfaces: FA0/1: 192.168.9.193 255.255.255.224 S0/0/0: 192.168.9.129 255.255.255.224 S0/0/1: 192.168.9.161 255.255.255.224 This is for my assignment at ...
2
votes
1answer
637 views

HP switch 'mirror port' makes a Cisco switch port err-disabled due to keepalive loop-back

I'm trying to connect an HP ProCurve 5304xl switch to a Cisco 2950. The HP port I'm connecting to is described as a 'mirror port', which appears to be like a SPAN port except that it also allows ...
2
votes
2answers
291 views

How to prevent recursive windows when connecting to vncserver on localhost

I have a VNCServer (vino) configured on my Ubuntu 8.10 box. I would like to connect to this server from a vncclient running on this same machine (the reason for doing this strange thing is mentioned ...
2
votes
1answer
847 views

Server hangs at “Shutting down loopback interface” on reboot

I'm having some trouble understanding what's going on with connecting one of our Xen hypervisors to our iSCSI SAN. Ever since we mounted our iSCSI targets, we've experienced hanging on reboots. This ...
2
votes
1answer
718 views

No network loopback device after security update ubuntu 12.04

I've had Ubuntu 12.04 on a server for the last several months, with everything working fine. Last night I did an aptitude update && aptitude safe-upgrade to bring in all the latest security ...
2
votes
1answer
523 views

Is there a security downside to having iptables ignore the loopback interface?

I have the following rules in my iptables (I cut out the rules that aren't relevant to this question): *raw :PREROUTING ACCEPT :OUTPUT ACCEPT -A PREROUTING -i lo -j NOTRACK -A OUTPUT -o lo -j ...
2
votes
1answer
4k views

How to enable HTTP loopback connections?

I running CentOS release 5.8 (Final) for my WordPress blog (www.deluxeblogtips.com). I have a backup plugin BackupBuddy, and it says: HTTP Loopback Connections are not enabled on this server ...
2
votes
2answers
3k views

Monitor loopback traffic (monitor MS TCP Loopback inteface traffic) with Microsoft Network Monitor 3.4 - possible?

I've downloaded NM 3.4 from microsoft.com and it appears that the software doesn't capture traffic on MS TCP Loopback interface. When I ping 127.0.0.1 address, NM shows no packets flowing. I've tried ...
2
votes
1answer
632 views

Boot Linux from a disk image on a Windows partition

I'd like to install Fedora 15 to a disk image on a Windows 7 partition, then boot from that image using the Windows 7 native boot loader. The advantage of this would be to avoid resizing the NTFS ...
1
vote
1answer
122 views

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 ...
1
vote
7answers
5k views

Server with slow ping response

Two boxes with identical loads serving the same sites tend to slow down and stop responding to ping. The slow (or intermittent) ping causes our load balancer to think the servers are offline and ...
1
vote
2answers
3k views

Disable ipv6 loopback

I am trying to get the IPv6 loopback completely disabled/disconnected. Searching the posts here I see everything that I have done so far. 1)Un-check the IPv6 on the adapter which will disable IPv6 ...
1
vote
2answers
1k views

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 ...
1
vote
5answers
7k views

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. ...
1
vote
3answers
591 views

CentOS - massive usage on loopback interface

I have a CentOS installation which is running fairly smoothly. Today I ran ifconfig mainly to see what sort of usage has been coming across the ethernet interface, and to also check my link speed. ...
1
vote
1answer
105 views

Is it okay to copy an image file which is still mounted via a loop device?

I have a 100 GB image file which is created using dd. This image file is mounted via a loop device as read-write. I want to store a backup of this image file at a remote location. I have a script ...
1
vote
1answer
263 views

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 ...
1
vote
1answer
141 views

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 ...
1
vote
2answers
988 views

route packets through hardware loopback interface, not lo

My embedded Linux board has 3 interfaces: eth0 - For all outbound traffic eth1 - A hardware loopback (traffic leaves board, but comes immediately back in the same port) lo - Standard loopback ...
1
vote
1answer
101 views

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 ...
1
vote
1answer
486 views

Is adding servername as an alias for localhost/loopback correct?

On linux systems, I've seen many variations of /etc/hosts configurations with regards to the loopback address, localhost, and server aliases. Some include the servername as an alias for the ...
1
vote
1answer
933 views

XEN: Error: Device 769 (vbd) could not be connected. Failed to find an unused loop device

I'm trying to start a new DomU machine (Lenny) on an Ubuntu Dom0. However, I'm getting the following error when executing the xm-create command: # xm create vm3.rootspirit.com.cfg Using config file ...
1
vote
1answer
997 views

Bandwidth limitations of network loopback device?

I have several JVMs that all listen to TCP 80 each bound on their own 127.0.100.1 -> 127.0.100.255 range. Is there a theoretical limit to the effective bandwidth that can be pushed through the LO ...
1
vote
1answer
30 views

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 ...
1
vote
1answer
747 views

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 ...
1
vote
0answers
161 views

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 ...
1
vote
0answers
766 views

ext4 loopback device, Buffer I/O Error on reboot

I am trying to mount a loopback device on my ext4 formatted ssd drive. I get these errors when I reboot on Linux kernel 2.6.38.8 Buffer I/O error on device loop1, logical block 0 Here is what I do: ...