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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138
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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 ...
10
votes
5answers
26k 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 ...
6
votes
4answers
2k views

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.mysite.dev 127.0.0.2 foo.mysite.dev 127.0.0.3 ...
5
votes
1answer
4k 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 Doctoring)....
4
votes
2answers
12k 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 ...
26
votes
7answers
9k 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 ...
5
votes
2answers
2k 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
1k views

iptables DNAT from loopback

I'm trying to understand the limitations of using iptables DNAT with loopback addresses. Consider we have an application which can connect only to 127.0.0.1; the obvious solution to make server and ...
0
votes
2answers
2k views

Group Policy Exemptions using filters

I have set a policy to enforce screensaver with a lockout after 7 minutes prompting for password. I have found that there are a few machines as exemptions. I have made another policy to disable the ...
0
votes
3answers
300 views

Avoid write on a mounted loopback device to be propagated

I have a device that mounts its root file system using NFS. On my NFS server I have a file representing the device's file system, namely target.ext2, which I mount on the appropriate /export directory....