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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Martian packet with ARP broadcast traffic
Server nodes keep getting ARP broadcast traffic and becoming martian packets due to assymatric routing. I was known that when strict filtering is enabled with net.ipv4.conf.eth0.rp_filter = 1, the ...
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Redirect Traffic on OVS switch
I have below topology on mininet:
Host1:10.0.0.1/24 mac :aa:00:00:00:00:01
Host2:10.0.0.2/24 mac :aa:00:00:00:00:02
Host3:10.0.0.3/24 mac :aa:00:00:00:00:03
I want to redirect traffic as below:
When ...
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MITM attacks inside VPN network?
Is it possible to use any MITM attacks (including ssh-mitm) if I'm connected to a VPN? OpenVPN connects me via tun0 interface with some IP in 10.0.0.0/8 and gateway at some IP 10.0.0.0/8. I know that ...
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How ARP (address resolution protocol) works with ethernet bonding?
We use a dual network card server with bond in 802.3ad mode. The outgoing bandwidth on both network cards is balanced, but the incoming bandwidth is concentrated on one network card. This issue is ...
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How to find device names on local network?
Currently I'm trying to write a Python script to scan through my local network, and list all of the active IP addresses, and their corresponding MAC address and device name. Also all of the devices ...
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Ping request generates response but sender doesn't see response
I have an embedded linux system with an ethernet PHY that is connected to a switch and then directly to my PC. After setting static IP addresses I found I could not get a working ping in either ...
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Is there a method of performing "local arp" requests on linux
I have some code that performs an arp-scan, I wondered if there was a way within a single machine to have "something" respond to arp-scan within the same host.
I've tried a few things so far ...
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How can I use nmap against an IPoIB network?
I'm trying to use nmap to check which services are running on a given network but it cannot start just because nmap issues ARP Ping Scans on IPv4 network, and on a Infiniband Network, as far as I know,...
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Linux confusing MAC addresses for its IP addresses to Cisco switch?
I have multiple CentOS boxes (both Centos 7) with two different servers. These servers have 4 10GB interfaces each. They are connected to two Cisco Nexus switches. Each NIC has a different IP address, ...
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Packet capturing using arp poisoning and IP forwarding
I made a script in Golang that allows me to perform ARP poisoning attack and with that I enabled IP forwarding to forward the packets to my router. When I use pcap.OpenLive I can only see the packets ...
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Host ID's on Network not in succession of 'active' or established devices?
Disclaimer: I am new to networking.
I ran a arp -a command on Terminal to establish what devices are currently active on the network. I was returned a number of devices with Host ID's that were not in ...
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List all active devices in different subnets?
My company has a class A network that contains various subnets. I need to automate a way to produce a list of all online devices (in all the subnets). To start, just a list of responsive private IPs ...
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ARP requests not passed between instances across the same subnet or connected to the same router
I have a k8s cluster deployed in OpenStack which for communication uses internal network and only the Master nodes have floating IP's in the external network. I am trying to use MetalLB load balancer(...
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Bridging firewall between two sites with same network
We have been assigned an IP-network for a test lab we can use for our equipment. To make sure our mistakes wont leave us nor anything from the outside will disturb us we want to setup a firewall ...
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Using a VLAN in embedded linux and although a response is received no entry made in ARP table
I need to set up 2 VLANs, but I have this issue even with only one configured (.2) but when I set up the other VLANc (.1) it seems to work ok.
The issue is that ARP doesnt seem to work which sort of ...
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Linux: Why is ARP not answered via VLAN Bridge
Our Goal
We want to run a server with several QEMU VMs, some of the VMs should be connected to separate VLANs. The host is connected to a switch via bonding and should have a VLAN-aware bridge where ...
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Network ARP scanning for unknown ip address
Today, i did Wireshark network capture on a LAN, i've found a broadcast storm from a computer.
The broadcast storm has stop but i would like to know why and what cause this broadcast storm.
Here is ...
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Linux is answering (wrong?) to Gratuitous ARP message
I've a Centos 7 Linux server with 2 physical interfaces, each of them has 2 subinterfaces, which are P2P /31 interfaces two Cisco. After changing neighboring Cisco devices Linux router started to ...
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Why can't ndisc6 update the kernel neighbor table?
I've been doing some work with ARP/NDP and discovered that ndisc6 doesn't update the neighbor table (unlike arping).
arping example:
192.168.0.14 is configured on a device connected to a VLAN member ...
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ARP Cache Entries Invalidated
I am doing some SDN research. In order to avoid having to route ARP packets, I manually set arp IP to MAC mappings on the hosts using the arp -s <ip> <mac> command.
Link failures are ...
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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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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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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 ...
google-cloud-platform
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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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