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.

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How can I capture traffic for a daemon listening on a cloned loopback IP address?

I have a daemon listening on a virtual IP address attached to a cloned loopback interface (lo1) on FreeBSD 11.x. Inbound traffic for that daemon could arrive on several different physical interfaces, ...
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How to disable loopback log “OPTIONS * HTTP/1.0” 200 - “-” "Apache/2.4.6 (CentOS) OpenSSL/1.0.2k-fips PHP/7.2.27 (internal dummy connection)

I get this in my access.log, so I have Googled and found some pointers but none of them work. How can I stop logging: loopback req "OPTIONS * HTTP/1.0" 200 - "-" "Apache/2.4.6 (CentOS) OpenSSL/1.0....
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iptables loopback opens all ports

I have a strange problem with iptables and my loopback interface. ifconfig says: lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 ...
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ssh -R binds to 127.0.0.1 only on remote

I'm running ssh -N -f -R127.0.2.3:23000:127.1.2.3:23000 user@remote , and I expect the tunnel on remote has opened on 127.0.2.3:23000, but it only opens on 127.0.0.1:23000, and it's inconvenient ...
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Loopback interfaces is not pinging on both pcs for packet tracer

I am trying to ping my isp ip address (aka loopback 1) and loopback 10 to PC1 and PC2. Whenever I ping both ip addresses and default gateway from pc1 to pc2 it works. However, when I'm trying to ping ...
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Is there such thing as a multicast LOOPBACK IP address, which won't leak packets from my host?

I need to work with and test a multicast application on my machine. If I configure its multicast IP to be something like 224.0.0.0, it will interfere with my other co-workers who are also working with ...
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Can't access a local https website on a nlb cluster node

I have a public IIS hosted web site running on windows server 2016. This server is member of a windows nlb cluster. I can't access this web site through https directly from the cluster nodes. This is ...
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I have a loopback traffic in linux involving port 631 and I have no idea what is causing it

So I did some packet capturing in my networking and everything else is actually fine except for this weird communication where source and destination is literally 127.0.0.1, source port is 631, and ...
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How do I enable tx-checksum-ipv4 for localhost? Raw socket capture incorrectly reports that all packets have invalid checksums

The checksums of all TCP packets transiting localhost on my vanilla Linux box (laptop) are being reported to be incorrect. Confusingly, data generally shuttling around lo is not being dropped on the ...
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Loopback adapter cannot connect to the domain network

I am working on a project creating Microsoft Print Server Farms with High-availability. It works perfectly with the Loopback adapters in the servers and a network load-balancer. The Loopback adapters ...
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Calculate pm2 ram consumption on basis of hit or traffic

I have deployed loopback backend application in ec2 instance. I am using Pm2 server. How can I calculate ram and cpu for traffic or hit ?
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IP Address is very slow compared to loopback address

I have an AWS EC2 VM. I want to run a bunch of scripts on a PostgreSQL server hosted on the same machine. When I use the IP address of the server in scripts, it took almost 5 seconds per script. But ...
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Network loopback device missing in Ubuntu 14.04

I want to program an FPGA via JTAG and the xmd script connects to 127.0.0.1:3121 to do so. That worked nicely for months. After a reboot this connection suddenly didn't exist any more, I cannot ping ...
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Add-NetNatStaticMapping not port forwarding to local VM

I'm running windows 10 build 1809 and have hyper-v installed. I have a Linux machine running behind a NAT with internet connectivity working on IP 10.0.5.5. I basically followed instructions on the ...
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Does Loopback able to support all TCP/IP protocols

Does a Windows loopback adapter supports ACD and duplicate IPs. Say we have a code that supports full TCP stack and we bridge the program to loopback using PCAP. If in case I set both the address ...
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How can I count / view all fast-path sockets on windows server?

In case you're not familiar, fast path loopback sockets: https://blogs.technet.microsoft.com/wincat/2012/12/05/fast-tcp-loopback-performance-and-low-latency-with-windows-server-2012-tcp-loopback-fast-...
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Windows Loopback adapter not participating in local network

I have created a Windows loop back adapter with 'Obtain IP address Automatically' enabled. ipconfig /all Ethernet adapter LL Address: Connection-specific DNS Suffix . : Description . . . . ....
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ip command equivalent to `ifconfig lo x.x.x.x up`

I am trying to set bind loopback to an IP address with ip link set lo 10.254.254.254 up but keep getting the error Error: either "dev" is duplicate, or "10.254.254.254" is a garbage. I googled the ...
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Corosync cluster will not bind vips to loopback, so apache fails to start in CentOS 7

I have a problem getting apache to work in a corosync cluster. I probably sifted through more than hundred web pages and a couple of dozen Google Searches, and was not able to find any matching ...
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How can i add a second ipv6 loopback address in centos7?

How can I add a second ipv6 loopback address in centos 7.4? I added the first loopback address to /etc/sysconfig/network-scripts/ifcfg-lo with ipv6init and ipv6addr_secondaries: IPV6INIT = yes ...
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How can I give access to loopback devices which are created dynamically to a Docker container?

I have a small Docker container from which I can access /dev/loop0. For this I've added to docker run: --device=/dev/loop-control:/dev/loop-control \ --device=/dev/loop0:/dev/loop0 \ On this ...
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Add second ip to loopback on Centos

We currently run Suse servers and add the following to the loopback interface: vi /etc/sysconfig/network/ifcfg-lo # Loopback (lo) configuration IPADDR=127.0.0.1/8 IPADDR_2=192.168.0.91/32 NETMASK=...
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Nat Loopback - Access external IP from internal

I have a static IP and I've made a webserver that is running fine from WAN (domain points to my IP). However, when I access my external IP/Domain from my LAN, it redirects me to my router login page. ...
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Err-disable in Switch 2960 [closed]

I have a problem. I have a Cisco 2960, this switch conect 23 Macs. The problem is that a pc puts the port in err-disable. When I put the command "show interfaces status err-disabled" the output is ...
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Kubuntu 17.04 on VM: loopback interface routed “outside”

Disclaimer: Yes, I know my problem description might be not very accurate and my terminology as well. Can not change that since I am new to this topic and do not know it yet. But I apprechiate ...
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How to change loopback network mask or redirect subnet to another interface [closed]

I have the following problem. First of all. Here are my interfaces. # ip addr ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd ...
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A looped hub connected to a switch

---- We don't want to block the use of Hubs --- If two switches are connected to each other via a hub, STP detects and blocks alternate link (if available). But if a hub is connected to even one (...
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iptables dnat not working for https

I have an http server listening on ports 8080 (http) and 8081 (https) on 127.0.0.1 I have these iptables rules to redirect from/to $external_ip: iptables -t nat -A PREROUTING -i eno1 -p tcp -d $...
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Heavy TCP traffic on loopback

While trying to generate some test traffic on my loopback interface, I noticed there was so much noise there that the output from Wireshark was essentially useless, with tons of SYN/RST, ACK packets ...
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Why adding external IPs to loopback (lo) works just like adding to ethX

For ages(>7yr) my automation scripts were adding new external IPs to the servers in this way ifconfig lo:0 11.22.99.44 netmask 255.255.255.255 ifconfig lo:1 11.22.33.44 netmask 255.255.255.255 ......
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How do I force localhost resolution to be 127.0.0.1 instead of ::1?

I'm running Windows 10 x64 and I have a legacy application that doens't work fine with localhost being translated to ::1, but instead it works for 127.0.0.1. How do I force Windows 10 to resolve ...
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TCP packets dropped in ipv6 loopback

Just logged in to a Windows host, I noticed an unexpected CPU usage. I quickly found out the processor was being hogged by the Windows firewall services. I enabled logging, and I started to see ...
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using ethernet ipv4 as internal bus while allowing the full ipv4 address range for the external interface

We have designed a device to be used as one device, but using ethernet ipv4 inside to communicate with internal not linux-based ipv4-speaking peripherals, juste like what we could do using pci or usb, ...
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Is it important to use localhost/127.0.0.1 rather than machine's own IP address?

I'm on Amazon AWS EC2 running Amazon Linux, though that may not be significant to the answer. Say I have three hosts, H1, H2, H3, with private IP addresses of 10.0.0.1, 10.0.0.2, and 10.0.0.3. This ...
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584 views

Ubuntu rename loopback interface

I have a Linux box with Ubuntu 16.04. I've noticed some odd behavior when I needed use the loopback interface. So I checked with ifconfig first and it showed that: rename1 Link encap:Local ...
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Can't access server on loopback address, only on private address

I am running a rails web app server bound to 0.0.0.0 on port 80 like so: sudo rails s --port=80 --bind=0.0.0.0 I can access it at my private address http://192.168.0.13/, normally I can access at ...
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How to create image file and mount via. loopback (Ubuntu to remote backup space)

I've been fiddling around with the Hetzner Backup Space and I want to use rsync via. rsnapshot in order to back up my files (more info at their Wiki here) They state in their documentation: The ...
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Slow “ifconfig lo”

How can I diagnose a slow loopback interface? Here is what I see on my Fedora23 box: $ time ifconfig lo lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 ...
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Server send TCP ACK with wrong number after receiving SYN

I have a client establish new TCP connection then sends request to a server per second. Both client and server are on the same linux box (via loopback interface). The client periodically reports ...
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Two loopback adapters communication in windows 7 or 8

Once our development systems are upgraded from windows XP to windows 7, my debug setup has stopped working. Steps followed in original setup (Windows XP): Add two loopback adapters Assign ipv4 172.16....
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Centos 7.1 Create Loopback Interface [duplicate]

I'm trying to alias an ip address onto Lo or create a new loopback interface such as lo:1 I've created /etc/sysconfig/network-scripts/ifcfg-lo:10 DEVICE=lo:10 IPADDR=192.168.10.1 NETMASK=255.255.255....
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Why only a single loopback address on IPv6?

IPv4 allocates a whole block of IPv4 loopback addresses, 127.0.0.0/8. IPv6, in contrast, only allocates a single loopback address, ::1. This seems surprising that IPv6 would be so stingy in its ...
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Network Traffic fluctuating, even with loopback

I am using iperf tool to benchmark my network interfaces on two identical machines (Dell Blade Server M620). Both have given different results. On 1st machine, I ran server and clients as: Server ==>...
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Loopback Processing Merge Mode

I am part of a team of IT Engineers who are currently revamping a large organisation. The previous IT department had some Group Policy objects in place for installing software(s), applying security ...
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Why is the loopback device needed on a client side of Stunnel?

This SANS Institute guide states that "On the client side, a port listening on the loopback interface of the local system would send/receive data on the clear-text protocol and tunnel out on ...
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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) ...
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Terminal Server and loopback address usage

Been trying to research this question to no avail yet!. Perhaps somebody can help. I am trying to identify if localhost on a TS works in the same way as a straight server. If I have an application ...
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Adding a virtual NIC to a 2008R2 server makes internet unreachable, why?

I currently have a Windows Server 2008R2 box with a single physical NIC. For what I want to do I need two network adaptors in the box. To accomplish this, I added a legacy hardware device "Network ...
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Forwarding a port on the loopback interface to a remote IP/port

I have two Docker containers that I'm trying to network together in a specific way. Container A is running a Redis server on port 6379. Container B is running an interactive shell and needs to access ...
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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.