Questions tagged [loopback]

Loopback means the interface created and designated to test a local port or interface. It routes test messages from their source device back to the source without any processing or modification. For TCP/IP on an ethernet interface, the loopback IP address is usually 127.0.0.1.

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connecting 2 VLANs on same switch will cause loop? [closed]

I was wondering if I connect 2 VLANs on the same switch would cause a loop ? If yes, why does it ? because every 4 ports are in other vlan I've added a picture to demonstrate
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Linux: how to suppress listing loop devices when using mount command?

Is there a way to prevent including loop devices when using mount command on its own in order to list existing mounts? When there are dozens of loopback devices it's tedious having to sift through the ...
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VMware WKS guest/host bridged connection via loopback adapter

My guest on VMware workstation are bridged to host network and it works perfectly. guests see each other and able to communicate. If I am not connected to my network it do not work because te host ...
flugsaurier's user avatar
2 votes
1 answer
364 views

Linux UDP server always show 127.0.0.1 as source IP

I'm trying to send UDP packet from a different loopback IP, say 127.0.0.100. There is no problem receiving the packet, while it always shows source IP of 127.0.0.1, and replies to there. Is there a ...
Haocheng's user avatar
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2 answers
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How is it possible that one computer access another computer's localhost(127.0.0.1)?

I know what does localhost, 127.0.0.1, means. It means loopback address, which can make a computer use as remote system. Of course, I know it is not possible that localhost cannot be accessed from ...
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1 answer
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Possible to use shell script that does loopback to localhost when receiving a packet?

I want to run a shell script, that sends a packet to localhost (loopback) when it receives a packet from anywhere. I am using netcat. nc -lp $port, and then echo test | nc localhost $port works. But, ...
BipedalJoe's user avatar
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Is this a cyberattack? Weird loopback file system in /tmp/tmp.050Scy377O/udf_ro

I noticed a strange-looking loopback file system being mounted on my linux machine, and dug into it a little bit. Does this look like some sort of hacking attack or cyberattack to any security experts ...
reikred's user avatar
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Virtual Camera Modus in OBS turn video into green / pink glitch (Ubuntu)

I want to use my Sony Alpha 6100 as a virtualcam via OBS on Ubuntu 22.04. OBS also finds my camera as input via gphoto2 and v4l2loopback-dkms. The image appears in OBS and looks good. As soon as I ...
RabeaMue's user avatar
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1 answer
161 views

What is the use of three separate routing table entries for loopback?

The loopback address is 127.0.0.1/8 right? Then wouldn't the first entry (in red box) itself take care of all the loopbacks? What is the need for the next two entries (in blue box)?
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OS X Audio hiss/dropouts on recorded loopback audio

I've been trying to achieve a desktop audio recording loopback setup like this one https://www.youtube.com/watch?v=AGc42kDiND8. So far, all of my attempts produced audio recordings containing hiss/...
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iptables repeated entry, what is the logic behind it?

I bumped into these iptables entries for a specific scenario I needed to replicate! iptables -F iptables -P INPUT DROP iptables -P FORWARD DROP iptables -A INPUT -i lo -j ACCEPT iptables -A INPUT -m ...
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2 answers
989 views

How do I override the automatic address assignments on the loopback device?

Background On modern linux systems the preferred way of managing network interfaces, ip addresses and routes, and related things is tools from the iproute2 package. I am trying to set up a somewhat ...
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Need help to create a loop to copy and paste data in a certain way

I am struggling with a loop from past 3 days, finally requesting help from the community. I want to each cell in column M from (input sheet) to output sheet in column BE multiple times based on the ...
Ajay Gaikwad's user avatar
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655 views

Excel VBA - Loop to Compare Cells, Offset entire row

Hopefully someone can help me with this! Just started learning VBA. I am trying the following code. The aim is to compare cells in rows starting from row 4 to and offset entire row up or down based on ...
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Cannot detach file-backed loop device after unmounting

I have some image files that I often use for cross-compilation work via chroot. My usual deal is to create a loop device with it, mount its main partition, bind mount /dev, /proc, /sys, and maybe /etc/...
Mona the Monad's user avatar
3 votes
1 answer
7k views

Create a virtual input device that loops back audio output, if Stereo Mix is unavailable?

I want to use Friture to analyze the audio from my speakers (while working on sound synthesis). I have seen tutorials mentioning Stereo Mix, but as I don't have the Realtek Audio Driver, this is ...
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Vnc viewer error: unable connect to socket: Connection refused (111) in CentOS 8

I would like you to help me with the following problem. I will try to give as many details as possible. I recently installed a vnc server on a Centos8 virtual machine. I have done all the ...
Andres Valarezo's user avatar
2 votes
1 answer
4k views

Pulseaudio loopback into headphones

I have headphones and a mic attached to my computer. My headphones are tight and block out external noise far too well, and so I find myself shouting at the mic. Is there any way of setting up ...
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Why is IPv6 not so heavily using loopback as IPv4 does?

Why is IPv6 not so heavily using loopback as IPv4 does? My OS: Linux Mint 20, kernel version 5.4.0-42. For the purpose of generating the output below, I defined an alias: alias iptables-watch="...
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FFmpeg output sent to v4l2loopback video device won't be read by guvcview

I set a dummy camera /dev/video1 with v4l2loopback module. I can read the stream with ffplay, vlc or even zoom of this camera when I send to it contentwith ffmpeg: ffmpeg -re -i input-file.mp4 -f v4l2 ...
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Take active cells value and copy to another cell. Excel VBA

I am putting together a list to loop through in Excel. I want to loop down column A starting at A2, and copy the value from the active cell to D2 (always D2) This is what I have so far: Sub Test2() ...
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Mounting as loop device fails with "wrong fs type, bad option, bad superblock, ..."

I tried $ mount -o loop ./live-cd.iso /mnt on a Live-OS image, which failed: mount: /mnt: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error....
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Is a /dev/loop preferred for mounting file-as-filesystem?

I have been hacking around with files as filesystems, for things like encrypted volumes and the like. This tutorial uses losetup and a /dev/loopX device to facilitate the mount process. However, ...
DeusXMachina's user avatar
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177 views

What is the bottleneck of loopback?

Recently I am curious about that question, so I installed iperf3 on my macOS to benchmark my the performance of the loopback on my macOS. However, the CPU usages didn't reach 100%, which is expected ...
guo's user avatar
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loopback api - persist AccessToken

First and foremost, my setup: Ubuntu Server 18.04 Loopback API 3.X Node version 12.6 My issue: I set up Loopback API and created a few models and users. Now, all I need LoopbackAPI for is really ...
Steven's user avatar
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2 votes
1 answer
5k views

How create loopback interfaces in Linux permanently

I aim to create 2 loopback interfaces and have them saved permanently in EC2 instance on AWS Linux Ubuntu based. I did the following in /ect/network/interfaces auto lo lo:1 lo:2 iface lo inet ...
Khalil Mebarkia's user avatar
0 votes
1 answer
771 views

RouterOS Hairpin NAT not working

I am trying to achieve this. https://wiki.mikrotik.com/wiki/Hairpin_NAT WAP IP: static LAN IP: 192.168.1.1 Web Server: 192.168.1.88 I can get to the web server from outside without any problem ...
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Requests to all Localhost Ports through Browser return "connection blocked"

I wanted to open page on localhost that used to work before but this time browser showed only (as html <pre> tag's content) connection blocked Other Apache pages on other ports are not working ...
Filip Wachowiak's user avatar
1 vote
0 answers
673 views

I need to create a dummy network adapter with a specific.customizable MAC address

I am trying to put a band aid on a very flawed piece of software, and need to create a dummy network adapter in Windows that will have a MAC address matching one of my real network adapters. This ...
TechBA's user avatar
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3 votes
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Working around the Network Loopback Isolation of UWP Apps

I've been hitting a blockage trying to get my UWP App to receive data from a local UDP port in the following scenario: Windows 10 | Version 10.0.16299 Build 16299 UWP target and minimum Version 10.0....
Coresual's user avatar
0 votes
1 answer
198 views

unexpected network loopback device on linux [duplicate]

executing ifconfig I found network loopback device which was not expected to show (maybe some linux packages created it on it's own?) but I would like to analyze it what it does - any ideas how to ...
quester's user avatar
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1 answer
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How to create a Loop in Shell Script to do a specific task?

I am trying to clean a Huge database of emails, but when I use the following Grep command, I get "Memory Exhausted" Error. pv "Suppresion-List.txt" | grep -vf <(sed 's/^/^/; s/$/$/' EMAILS.txt) &...
Joney Walker's user avatar
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2 answers
661 views

loop(repeat) script block until successful db(mysql) password

I have the following function function executeMySql() { while IFS= read -p "$prompt" -r -s -n 1 char do if [[ $char == $'\0' ]]; then break fi if [[ $char == $'\177' ]...
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5 votes
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Why is loopback on Windows 10x slower than loopback within a Linux VM?

I have been testing the speed of my windows machine's loopback adapter using iperf3 which has given the following results: However, when I run the exact same test within a linux virtual machine ...
Alexander Rafferty's user avatar
4 votes
1 answer
2k views

Enabling NAT loopback on Zyxel C3000Z Modem/Router?

I have a C3000Z router from Century Link and it does not have NAT loopback enabled by default. The option is simply not available on the Web GUI. However browser around I found a few other models of ...
Alex's user avatar
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1 answer
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Make localhost server exempt from UWP app network isolation?

By default, UWP apps cannot access network resources on the same machine. This restriction can be lifted per app using the CheckNetIsolation.exe utility. This is described in many places around the ...
twisteroid ambassador's user avatar
0 votes
1 answer
149 views

How to trick a Linux program into "seeing" just the loopback network interface lo0?

The title says it all. I am trying to avoid the situation when a program detects the IP of a network interface and sends it to a remote location. I am thinking to do this by tricking the program into ...
Windows11's user avatar
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Monitoring network traffic from Microsoft Loopback Adapter

I am getting my internet connection through a Microsoft Loopback Adapter (coming from a Virtualbox), and because of loopback implementation, you can't monitor its traffic via Perfmon or Task Manager. ...
Spectraljump's user avatar
2 votes
1 answer
2k views

Speed of loopback interface

I am working now with nfs shares. And I want to connect to localhost with nfs. I have disk that can read/write ~400MB/s but when I connect to nfs on localhost I have only ~110MB/s. I read that ...
Przemek Tomala's user avatar
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0 answers
228 views

Is it possible to connect to the same computer WITHOUT loopback?

I'm trying to measure the speed of the connection between my computer and my router. I'm using iperf for this, but the problem is that entering my own local IP address bypasses the network and ...
user541686's user avatar
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Constant TCP requests and failed responses

I'm getting one of these per second: 457 205.494657 127.0.0.1 127.0.0.1 TCP 68 49507→23454 [SYN] Seq=0 Win=65535 Len=0 MSS=16344 WS=32 TSval=630136859 TSecr=0 SACK_PERM=1 458 205.494702 127.0....
Jason Schwartz's user avatar
4 votes
1 answer
3k views

Do we need NIC to ping loopback IP

I read that pinging loopback will work if we have TCP/IP suite installed on our computers and don't necessarily have a NIC. So, do we need NIC to ping loopback ip(127.0.0.0) ? Thanks.
Siva Prakash's user avatar
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1 answer
2k views

What is a "loopback", can it cause "damage"?

The high school I attend won't allow students to have the WiFi password. Our entire education system is evolving and becoming more and more dependent on the internet. Therefore, I brought my own ...
Griffink17's user avatar
1 vote
1 answer
4k views

NAT loopback on my router

Tried all for a day still can't get it done. I am trying to configure 'NAT loopback' on my router. Router LAN IP: 192.168.1.254 (br0) Router WAN IP: 192.168.10.129 Web-server LAN IP: 192.168.1.1 ...
Amit Shah's user avatar
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2 votes
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658 views

Loopback adapter breaks wifi

When I installed the loopback adapter on Windows 10, the wifi stopped working. Disabling the adapter makes the wifi go back to normal. The wifi adapter stays enabled, but just can't connect to the ...
Yuriy Faktorovich's user avatar
1 vote
1 answer
2k views

Differences between firebase, loopback and redux

I want to develop a web app and later corresponding android/ios apps. So far I have only decided the front end for which I want to use react and react native for mobile. For the rest of the ...
react-newbie's user avatar
4 votes
1 answer
16k views

How do you disable the loopback device windows 10?

I have found this question for Windows 7 many times (example), but this does not work on Windows 10, because I don't think the loopback network adapter is exposed in the same location. At least for ...
Frank Bryce's user avatar
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1 answer
747 views

Folder Redirection Not Working With Loopback Processing

I have an OU named TEST-OU where I want to apply Folder Redirection to all users in that OU. So far this has been working fine. Next I created a sub-OU below that one called TEST-SUBOU where I want ...
throwayusername's user avatar
3 votes
0 answers
9k views

Make "ping localhost" resolve to "127.0.0.1" instead of "::1" without the -4 option

Context We're wanting to use RawCap to inspect HTTP requests to localhost. RawCap though cannot capture IPv6. We've considered doing a massive find-replace of "localhost" with "127.0.0.1" in our ...
Shaun Luttin's user avatar
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6 votes
1 answer
3k views

iptables reject tcp-reset on loopback

I am trying to check how a software would behave if there is a network failure. That software is using tcp send() and recv() to communicate. Previously I was making the software communicate by ...
Haris's user avatar
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