Questions tagged [loopback]

This tag is for questions about loopback interfaces on network devices. For instance, you want to configure routing on your layer 3 switch and for that you want to configure a loopback interface.

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14 views

How to get my Pi zero audio simultanusly on my hifiberry and on ffmpeg?

Hope you can help me. Got a Pi Zero and Hifiberry Module playing with raspoitify. Speaker sound is fine. My goal is to have the same (raspotify) audio on a ffmpeg stream from that Pi as well. I ...
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35 views

How to filter (rate-limit) traffic through a bridge, using nftables, depending on whether or not the traffic originated locally?

I'd appreciate some help with understanding how traffic filtering in a bridge works, especially for packets / Ethernet frames which originated locally. To explain the problem, I'll shortly describe ...
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16 views

reordered and duplicated packets when using UDP over loopback interface

We are seeing UDP packets being reordered and duplicated when being sent over lo. We can see this because we're sending MPEG transport streams, which have their own sequence number in their headers, ...
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48 views

Pinging a shut down loopback interface from another system

We have two device R1 and R2 running FreeBSD 9.2, on R1 we have set an ipv4 address for lo1: R1#: sudo ifconfig lo1 192.168.80.80 Then add a route to R1 in R2: R2#: sudo ip r add 192.168.80.80 via ...
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46 views

Manipulate filesystem image files without loopback devices?

I am trying to automate the creation of Raspberry Pi images under Docker virtual machine to run it in common CI systems like bitbucket-pipelines. On physical system I am using "template" ...
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22 views

How to grab output of a remote ssh command with until-loop in a variable

Below is my until loop that fires a printer command to a remote host using ssh until ssh root@45.76.165.127 'lp -d Brother_HL_L2350DW_series /root/moht/Printed/`basename "$FILE"`' do echo &...
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30 views

BUTT - Streaming alsa loopback audio using BUTT to Icecast2 server

I've set up a radio for local network, everything (Icecast2, BUTT (Broadcast Using This Tool)) is ready and working except one thing. BUTT intends to capture audio from input device, but that is not ...
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1answer
104 views

i need to display Number of RX packets and the number of TX packets for the loopback interface [closed]

im new to linux and i need to display Number of RX packets and the number of TX packets for the loopback interface. i have tried using ipcongif but for reason i get an error, im using ubuntu for ...
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47 views

Is it possible to record external voice using loopback card created from the module snd-aloop?

Hi I created a loopback virtual card on my Ubuntu aws server machine. When i try to record my voice, it is not working. Steps I followed - Changed default kernel to generic Installed alsa-base , als-...
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25 views

Virtual ALSA device, sync / intercept volume commands

I have a stereo. I like it, because the sound is nice, but it's not quite sophisticated engineered: It has an internal USB Card soldered on some board, directly outputting audio to the power amp. ...
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1answer
71 views

IPv4 iptables blocks things, but output policy is ACCEPT, what is the problem with my INPUT DROP chain?

This is my IPv4 iptables list at this moment: Chain INPUT (policy DROP) target prot opt source destination ACCEPT all -- anywhere anywhere ctstate ...
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2answers
1k views

redirect external request to localhost with iptables

I have a service running on "localhost" address on a certain X port. Unfortunately, I can't change the address to "0.0.0.0" to expose that service. Can I use iptables to internally redirect request ...
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777 views

Does the loopback network inside the docker container shares host network loopback?

I recently faced issue with one client application which is running inside a container. This client making network connections to a server residing in the same container over loopback IP 127.0.0.1. ...
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271 views

retransmissions/out-of-order packets with large (~1 MB) writes/reads w/ TCP (SOCK_STREAM) over localhost loopback — ACK lost

I'm seeing retransmissions/out-of-order packets when using the loopback interface and have been googling for days to try to determine if I should be surprised by this (which I am) or if anyone else is ...
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1answer
24 views

How Can I Route A WAN IP Request To My Loopback Address And Port?

I have two virtual machines on my laptop. One of virtual machines want to reach an IP address (I have the IP) and I want to route this request to another virtual machine's port. I changed the default ...
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1answer
48 views

traffic going through lo interface checking every 4 ports

I have noticed that there' s always traffic going on on my loopback interface. It's not a lot but I don't know where it's coming from and I'd like to stop it. There's syn request going from port X to ...
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1answer
39 views

Understanding Netplan / NIC [closed]

I have a set of 5 static ip addresses. Currently I only have 1 server, so I want to route 2 static IP's to the same server. At the same time I still want the server to be part of the local network. ...
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1answer
120 views

Can't ping all the loop back addresses

As we know, the range for loopback addresses is 127.0.0.0 – 127.255.255.255. On my Linux box, I am able to ping all the addresses like 127.0.0.1, 127.0.0.2, 127.0.0.254, etc. (i.e., all addresses from ...
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1answer
95 views

Traffic into lo vs eth, why might I be seeing only half the traffic on lo compared to eth?

I am forwarding traffic to ports on eth0 and lo. For the same traffic at the same ports and different ports, when I do a tcpdump and count the packets, for time t, I only see about half the number of ...
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135 views

IPv6: Why ping to another IPv6 host doesn't work when loopback interface is DOWN

While it is said the only job of lo interface is to test its own connectivity, why doesn't pinging another IPv6 host work when the lo interface is made DOWN. Network configuration: host1(eth0) - ...
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2answers
47 views

How I manupulate these files in terminal at the same time

I have 139 different tab-delimited .txt files. I want to add a column to each file containing the name of that .txt file and finally attached all .txt files in one file; Let's say I have A.txt, B.txt, ...
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1answer
904 views

ALSA Loopback not recording system audio on Xubuntu 18.04 in ffmpeg command

I have an ffmpeg script to do my screencasts. I have Debian 9 at the office and Xubuntu 18.04 at home. On those two operating systems, the following works to record system audio and from my microphone....
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1answer
1k views

Microphone loopback on Linux

I am trying to do simple microphone loopback to immediately play to the speakers. I eventually got it working on one computer by running pacmd load-module module-loopback latency_msec=1. However, a ...
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0answers
222 views

Alsa snd-aloop: add more loopback subdevices?

I'm currently working on a project on which I need to create multiple audio streams using snd-aloop. The issue is that we reach the max number of substreams easily. Is it possible to have more than 8 ...
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79 views

New loopback device module does not show trace in wireshark

I am trying to write a network device driver that can duplicate the functionality of the loopback device. I modified the code available at the link. I am testing on Linux 4.8. I removed code related ...
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1answer
170 views

Reachability of custom loopback interface on different machine

I have a loopback interface on one machine with a certain IP address, and on another machine I have a static route to that loopback interface subnet. I can ping the other loopback interface when ...
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0answers
54 views

selinux restorecon on systems without selinux like ubuntu [duplicate]

recently i had to change two files on a fedora raw image mounted via loopback on ubuntu, which usually runs in a kvm on the ubuntu host. That made a lot of troubles with selinux after booting from the ...
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1answer
261 views

Linux audio loopback: Multichannel to stereo (for OBS usage)

I am using the RME Fireface 802 to record a stereo signal for my stream, but unfortunatly OBS won't accept Multichannel audio that contains more than 8 signals. So, since OBS doesn't like my ...
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1answer
2k views

Does `lo` have no MAC address?

From https://networkengineering.stackexchange.com/questions/57935/is-a-network-interface-supposed-to-have-no-more-than-one-mac-address/57937?noredirect=1#comment100988_57937 A network interface in ...
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4answers
1k views

why `nmap 192.168.1.97` returns less services than `nmap 127.0.0.1`? [duplicate]

According to https://networkengineering.stackexchange.com/a/57909/, a packet sent to 192.168.1.97 "doesn't leave the host but is treated like a packet received from the network, addressed to 192.168.1....
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1answer
1k views

How come one can successfully ping 127.0.0.2 on Linux?

On a FreeBSD system with a loopback network interface … % ifconfig lo0 lo0 link up loopback drv_running running multicast nd6 performnud auto_linklocal no_radr link rxcsum ...
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2answers
256 views

What does the action “loop back” mean? [closed]

I have some difficulty to picture a diagram for the meaning of loopback. https://en.wikipedia.org/wiki/Loopback#Virtual_loopback_interface Any traffic that a computer program sends to a loopback IP ...
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2answers
601 views

Are the IPv4 and IPv6 networks for my loopback interface the same network?

In output of ifconfig: lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen ...
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2answers
183 views

Why is some virtual network interface assigned private IP address, while some is assigned loopback IP address?

Are docker0, lo and virbr0 are virtual network interfaces? Why are docker0 and virbr0 assigned private not loopback IP address? If private IP address can work like a loopback address, can lo be ...
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0answers
553 views

Trying to make loopback device as Alsa-to-Jack bridge

Using this guide i trying to make loopback device as Alsa-to-Jack bridge. Everything fine until those lines # capture client alsa_in -j cloop -dcloop # playback client alsa_out -j ploop -dploop On ...
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1answer
38 views

Does “loopback” in a loopback file mean the same as in loopback IP address?

man pvcreate says pvcreate initializes a PV so that it is recognized as belonging to LVM, and allows the PV to be used in a VG. A PV can be a disk partition, whole disk, meta device, or loopback ...
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4answers
4k views

How can I do a loopback test?

Book Computer Networks says all addresses of the form 127.xx.yy.zz are reserved for loopback testing. Packets sent to that address are not put out onto the wire; they are processed locally and ...
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1answer
403 views

Is it possible to zero the free space on a LUKS volume?

I want to have a LUKS volume as a loopback device pointing at a sparse file. Lets say I put a 20gb file on it, then later I delete it. How can I zero that area on the device itself so I can fallocate -...
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1answer
659 views

Is it possible to boot a grub-mkstandalone created img file from cfg?

So I have a fully functional .img file created using grub-mkstandalone. I put this on a CD and it boots fine, the ISO loads great in a VM, etc... Now, what I want to do is link an existing grub.cfg ...
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1answer
78 views

default network on surface pro 4 is loopback

please look at this amin@amin-Surface-Pro-4 ~ $ ssh 192.168.1.10 -p 1366 ssh: connect to host 192.168.1.10 port 1366: No route to host amin@amin-Surface-Pro-4 ~ $ ifconfig lo Link encap:Local ...
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1answer
30 views

ipv6 route slightly modified

I am running GNU/Linux version 3.4.113+ with a 6in4 tunnel to a tunnel broker. If I run command ip -6 route list table local I see a lot of routes. And one of this route entries is this local ::1 ...
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1answer
4k views

ip6tables - IPv6 DNAT to localhost

I have the following IPv4 rules: iptables -t nat -A PREROUTING -d "server ipv4" -p tcp -m tcp --dport 80 -i eth0 - j DNAT --to-destination 127.0.0.1:55555 iptables -P INPUT ACCEPT In addition, I ...
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4answers
9k views

Is it possible to put a real IP on a loopback device?

Is it possible to put a real IP (not in the 127.x.x.x) range on a loopback device?
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2answers
946 views

OpenBSD: Defining a new loopback interface

I need one more loopback interface in my OpenBSD 6.1, with the IP address 127.0.0.2. I can create it by hand with the command: ifconfig lo1 127.0.0.2 And to have it at boot time, I just inserted ...
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2answers
1k views

Second loopback network interface (for netem)

I would like to add a second loopback network device on Linux, so that I have lo and (e.g.) lo2. This is so that I can use netem to simulate a throttled network over lo2 without compromising my ...
3
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2answers
6k views

How is the loopback network interface implemented?

The loopback network interface "is a virtual network device implemented entirely in software," according to another question on Unix.SE. But how is this implementation actually accomplished, and how ...