Questions tagged [arp]

Address Resolution Protocol is a layer 2 networking protocol used for resolving layer 3 addresses (such as IP addresses) into layer 2 addresses (such as Ethernet MACs). It is used by network devices when communicating with devices on the same layer 2 network.

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"PXE-E11 ARP timeout", "PXE-E38 TFTP cannot open connection" errors on client machine when connecting to PXE CentOS Linux server

For my setup at work, I am having trouble getting my test client to run PXE Linux from the PXE Linux Server I have setup from this walkthrough at: https://www.linuxtechi.com/configure-pxe-installation-...
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Getting the MAC address of a remote host? Linux, macOS, Linux [closed]

I am writing a custom application in Go. My app needs to work on Linux, macOS, and Windows 10+. I need to verify that a remote host is what I think it is. I've tried arping and as expected, it does ...
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NTP traffic causes frequent ARP requests

I am running Ubuntu LTS 22.04 using Chrony as NTP server. I discovered that even with frequent NTP traffic between a NTP client and the NTP Server, the ARP requests are still being sent back and forth ...
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Arp behavior on non requesting user for response

If we imagine we already have a valid cache for a pair in computer B and then composer A asks about the same pair and computer C responses with the pair information, what would happen here to computer ...
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Why MetalLB cannot provide a real load balancing feature in layer 2 mode?

The documentation of MetalLB states that: In layer 2 mode, all traffic for a service IP goes to one node. To my understanding, this is mostly due to the fact that: one node assumes the ...
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Linux MAC learning outside network

How can I forbid create ARP records in Debian for IP outside network assigned for device? For example: ip route 10.10.0.0/20 dev ens4f1.10 proto kernel scope link src 10.10.0.1 10.11.0.0/22 dev ens4f1....
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ARP Weirdness - Missing ARP replies?

Here's a picture of the relevant portion of my network. The problem is as follows: The Windows PC at left and the Synology NAS are both able to reach the two webcams (ping) and the ARP tables on ...
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ARP Reply is not forwarded to TAP device through Linux Bridge

Create two TAP devices, each of which will be read and written by the userland protocol stack. In addition, the two TAP devices are bridged by the Linux Bridge. The script to prepare the environment ...
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Using OVH VRack, 2 PVEs can't fully communicate

In OVH, I have 2 ProxMox servers, each one containing a Firewall and a few other hosts. I am trying to use OVH vRack for private communication between them, but it is not working. Here's a summary of ...
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Discover IP address of the device knowing only MAC address

While "wiresharking" the network, You may come across packets that looks like THIS eth.src to eth.dst (mainly colored white).. sometimes Wireshark recognize protocol LLC, NDP etc.. but ...
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Linux bridge doesn't respond to ARP requests after an ip rule is added

I have a virtual machine created with libvirt/qemu/kvm attached with a TAP to a Linux bridge (virbr1). Internally the VM has an IP of 10.99.0.9. And has the following routing setup. default via 10.99....
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ARP Connectivity Issues Between OpenMediaVault Server and BSD Jails

On my network I have two servers. Server1 is running TrueNas(BSD) with multiple applications running in iocage jails. It's connected to the network with a 3-nic LAGG. Server2 is an OpenMediaVault (...
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docker swarm temporarily stops accepting request in production

I am running an angular application in docker swarm in production. Randomly the application stops working for like 10 minutes. The containers are running fine. I see the arp -a says the arp incomplete ...
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How to send/broadcast ipv6-mac maping cache update request for IPv6 IP

We can update IPv4 neighbors by using arping command. I have used arping -A -I -c <interface_name> <IP_address_of_interface> with success. what is the command to update mapping of IPv6 ...
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Linux: What causes static ARP entries to flush on link down

This is a question about a difference in networking behavior between Debian Buster (kernel 4.19.0-18) and Debian Bullseye (kernel 5.10.0-9). On Buster, proxy arp entries survive if the link on the ...
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Proxmox ARP cache causing virtual machines MAC to change?

I am having an issue with Proxmox and ARP changing the MAC address of virtual machines. arp -a returns: ipxxx.ip-51-89-201.eu (51.89.201.xxx) at fe:ed:de:ad:be:ef [ether] on vmbr0 This virtual ...
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IPv6 connectivity suddenly lost, IPv6 neighbour router status becomes STALE at the same time. How can I avoid it?

I have a VM on a host with bridged networking (hence, with its own MAC address). Both host and VM run CentOS. Their network is managed by simple /etc/sysconfig/network-scripts/ifcfg-enpXsY files ...
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How can a user connected to Mikrotik router using ppp account reach DHCP clients?

I can connect to a remote Mikrotik router using L2TP server that is enabled in the device and has a public IP. Everything is OK when I try to reach all other routers and devices in that remote network....
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No responses to ARP requests

One of my server's physical interfaces eno3 is part of a bridge br0. There is also one LXD machine attached to this bridge (nictype=bridged, parent=br0). Sometimes ARP stops functioning completely. If ...
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Limit ARP to gateway IP only

My current network setup is as follows auto lo iface lo inet loopback dns-nameservers 8.8.8.8 8.8.4.4 auto eth0 iface eth0 inet static address 104.244.72.242/32 gateway 107.189.30.113 pointopoint ...
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Linux does not send arp reply

I have an interface keeping receiving arp request but never respond. Can anyone help? My interface ip is 192.168.40.2. The routing table looks good.
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Static ARP Entries aren't being added

So I'm trying to create a static ARP Entry with the ip and MAC Address of my router. I'm currently using admin command prompt and the command arp -s [ip] [mac address], but it isn't working. Every ...
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Why can't I arping the direct broadcast of the LAN to populate the arp table?

I'm trying to write a simple network discovery for my linux 2.6 router. I'm testing arping which is bult inot busybox. I can't work out why sending a single request to the direct broadcast is not ...
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can ping but not arping via OpenVPN

I'm working on a remote machine using OpenVPN at a customer's network. The IP addresses there change dynamically and (until they get hostnames to work properly which is not in my hands at this point) ...
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Windows Incorrect MAC Address Populating ARP Table

Recently I have been running into issues where incorrect MAC Addresses are populating the arp tables of some Windows VMs running in a Cloud Provider's cloud. For example, if I ping 10.1.2.3, some ...
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What are the symptoms of an IP address conflict?

System administrators must take special precautions when setting up two DHCP servers on the same network. The most common problem caused by competing DHCP servers is an IP address conflict. Windows is ...
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Strange entries in ARP table

I noticed some strange public IP addresses in the ARP table of my Ubuntu laptop. They also keep reappearing quickly after flushing it. The adresses all resolve to bc.googleusercontent.com and only ...
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Finding static IPs after reboot

I am having troubling pinging IP addresses on the local network after rebooting or clearing the ARP table. I am looking for guidance on fixing this. I have a windows 10 PC which is has a 4 port ...
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ARP table emptied when TAP interface is added to bridge

I have a problem with ARP table on CentOS. Sometimes, when I create a TAP interface and add it to a bridge, the ARP table is cleared up. E.g. when I execute this command: sudo ip tuntap add dev tap-...
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Same VIP different MAC

I am observing this behavior on a dual-homed server that is sending traffic in active/active mode on its 2 links connected to the same uplink switch. The server is running IPMP so it generates traffic ...
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How to make Linux kernel send ARP requests down multiple network interfaces with overlapping subnets?

I have a Linux PC with the following physical network interfaces: Primary LAN/Ethernet port used for most traffic. Ethernet (from external device) to USB (into my PC), used to connect to a single ...
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Google Cloud VPC: Is there any restriction on N-S traffic and ARP requests from alias IP?

Platform: Google Cloud VPC Scenario: We are trying to integrate our cloud infra solution within GCP instances using nested virtulization. The solution includes a SDN component which performs both L2 ...
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two tap device connect each other in same pc

What I want to implentent is something like below. 192.168.1.1 192.168.1.2 +--------+ +----------+ +-----------+ +---------+ ...
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rsync broken pipe between two servers on different networks

I have two FreeBSD servers, both on different networks, with a firewall in between. I have no control over the firewall. Server 1: IP: 10.1.0.2 GW (firewall): 10.1.0.1 Server2: IP: ...
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How am I receiving ARP brodcasts from a different subnet?

My local IP/subnet is 10.33.19.*/24, and yet I am occasionally receiving broadcasts requesting information from and concerning IPs in the 10.17.*.* range. I was of the impression that ARP requests do ...
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Unexpected ARP Probe and ARP Announcement on Windows 10

In our system, there are three hosts all connected to the same Ethernet switch, which is illustrated below: A (192.168.0.21, WIN10_1809) <-> Switch <-> B (192.168.0.100, Debian Linux 9) ...
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Why is my client still talking to my server when I change client IP to different subnet? [closed]

On occasion, I'm using a Verizon Mifi adapter to share an internet connection over my office network (which doesn't have internet). To do this, I have to share the internet connection on the adaptor, ...
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Lots of IPs with MAC 00:00:00:00:00:00 . What are the possible causes?

On my enterprise we have some times this ARP output (read on a computer with Linux): $ cat /proc/net/arp 192.168.0.176 0x1 0x0 00:00:00:00:00:00 * eth0 192.168.0.93 ...
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Proxy-Arp setup with Keepalived

I currently am trying to create a setup with N servers where 1 server is the master for a Virtual IP, and the (N-1) servers act as backups, presumably controlled by keepalived. However, one issue I ...
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How do l manually set an arp table entry to reach an otherwise unreachable host in debian

I'm trying to reach a host on an internal network whose configuration has gotten screwed up, and isn't pulling a DHCP lease as would be expected. I have a host on that network that l'm trying to use ...
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arping not working in docker

I'm currently trying to add a presence feature in my OpenHab installation by detecting presence of our mobile phones. For iPhone an arping is necessary, unfortunately it looks to me like arping won't ...
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Same IP on two NICs half the traffic is lost

I have a machine connected to a slightly broken scientific instrument and I'm trying to work around the problems. The link is point to point, 2x25G ethernet, no other devices involved. The device ...
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Is there is any tool/way to find out why packet is getting dropped due to an arp cache full?

My developer hypothesis is packet is getting dropped at arp layer. We increased the default value of neigh.default.gc_thresh3 1024 --> 2048 and now everything looks good. But I want to understand is ...
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Router ignores ARP response from linux

I have just viewed my local network traffic with Wireshark to solve a connection problem of another device. I noticed that my router constantly asks for my MAC address via ARP, but ignores the answers ...
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High bandwidth ARP traffic on LAN interfaces

I'm using a PfSense Firewall with a few VLANs since over 4 years and in the last couple of days I've noticed network connectivity issues in two of the VLANs. Using the web interface I'm seeing ...
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Debian / Kerio is ARP storming my ISP after loosing connection to the gateway

The problem: after Kerio Control (Debian) lost connection to the gateway it starts sending ARP like for "who has 8.8.8.8?" in such frequency, that the gateway gets shut down due to packet inspection ...
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QEMU/KVM/libvirt macvtap VEPA not working - ARP request not forward

Hi I've been struggling to get guest networking working when using a macvtap in VEPA mode between two VMs on a host. I've spent hours (days) googling with no joy. Does this network configuration ...
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why doesn't arp-scan find any devices when nmap does?

When I run nmap -sn 192.168.0.0/24 I get the result: Nmap scan report for 192.168.0.1 Host is up (0.16s latency). Nmap scan report for 192.168.0.103 Host is up (0.19s latency). Nmap scan report for ...
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NIC bonding on Linux in redundant network topology

I want to implement NIC bonding on Linux server in redundant network topology as shown in the network diagram below. Network topology Both interfaces of the Linux server fa0 and fa1 would be in one ...
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Why do some unknown hosts show up with nmap option-sL , and not with -sn [and do I need to worry about them]?

Initial Disclosure I am not a network engineer and my expertise in this area is low. Background while using nmap 7.70 with nmap -sL to look for the IP address of a known device on our local ...
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