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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pfSense 1.2.3 can't talk ARP beyond a switch two hops away

I have the following devices on vlan93 on my network: pfsense (192.168.93.1) core-sw1 (192.168.93.2) edge-sw1 (192.168.93.3) pf-switch (192.168.93.100) devices (192.168.93.120) Physical ...
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Cluster failover and strange gratuitous arp behavior

I am experiencing a strange Windows 2008R2 cluster related issue that is bothering me. I feel that I have come close as to what the issue is, but still don't fully understand what is happening. I ...
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0answers
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virtualbox bridged adaptor works only guest->host but not host->guest

I have virtualbox 4.1 on a ubuntu 12.04 host. On my host I have a virtual interface eth0:1 configurend as 10.0.1.1. I have a few virtual machines using bridged adapters, configured in the 10.0.1.0 net ...
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2answers
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Routing to other subnets results in wrong ARP requests

I would like to manually set up routing to subnet 95.168.0.0/16 through IP which is an alias: 94.23.94.161. IP alias is set up like that: /sbin/ifconfig eth0:0 94.23.94.161 netmask 255.255.255.255 ...
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1answer
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Why ARP request is unicast?

I have a wireshark capture that indicating a unicast ARP request from source to destination. As per my understanding ARP requests (including gratutious ARP) use broadcast. In what case the ...
0
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1answer
877 views

One To One NAT, only works on WAN?

We are attempting to test a One To One NAT configuration on a Cisco RV180 router, Cisco SMB support says that this setup below would not work. (they seem to be right) I know it has something to do ...
5
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2answers
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Ubuntu 12 crashed and took down network

We recently set up a new Ubuntu 12.04LTS server on our network. It's not fully configured so it's not doing much beyond sshd and a default apache2 install. But this evening it appears to have ...
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2answers
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Will a host accept any ARP response it gets and updates its cache

I am trying to understand ARP and ARP cache poisoning. Will a host updates its cache if it gets an ARP response even if it didnt send a request? If yes, is there any particular reason it is designed ...
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2answers
353 views

Activate Passive Arp learning

I want to enable my linux-kernel to passively listen (learn) the arp request broadcasted in the lan segment (arp request in the network not destined for me). Is there any configuration available?
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1answer
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pfsense single MAC is listed with several IP's in ARP table

I have this problem: arp table filling up But I am quite sure that I cannot blame Kaspersky. Scenarie: a user plugs his computer in. He waits and waits but are getting no IP by DHCP. Then he is ...
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2answers
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Why computer scanning network?

I have found out through Wireshark that a computer in my subnet scanning network ( sending ARPs for every IP-address in my subnet. Even if there no computers with such address). It repeats ...
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4answers
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Extremely high arp fllooding from the router

My subnet is 10.162.0.0/16. We have a router with a couple of interfaces. Gateway for my subnet is 10.162.0.1. The router is situated in another building and I haven't direct access to it. Line from ...
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1answer
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How can I find out the source of arp request if it is in another subnet?

Our subnet is connected with other subnets with router. Using wireshark I see some arp requests coming to ip addresses of our subnet from the router. Such as Broadcast ARP 60 Who has ...
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1answer
214 views

How to force a host to not send a broadcast for an IP address in its own subnet?

For a LAN, instead of a switch, I have built a topology where each machine is connected to a router. Each host is assigned an IP address from 10/8. Here are the interface details: Lets say I ping ...
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4answers
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What happens when ARP Request comes from a different subnet?

What will happen when an ARP Request packet is sent from router1 to router2 in the following two cases? Will an ARP Reply be generated or the ARP Request packet be dropped? ...
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1answer
703 views

What is the effect of stale ARP cache entry on traffic to that DIP till the entry ages out of the ARP table?

If the host, for which an ARP table entry is present on the connected router, has changed its NIC(so that its MAC address has changed), what will happen when a packet is sent out on the link with the ...
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2answers
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arp “who-has tell” on cloned machine

I have a urgent problem to solve today, but I'm lost. Please help. I've cloned a Virtual Machine hosted on VM Ware ESXi 4.1 The OS is now Ubuntu Server 12.04 LTS, but at the time of cloning it was ...
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3answers
1k views

ARP broadcast and router performance

My employer subscribes to a fiber based leased Internet from a publicly owned incumbent ISP. The ISP admin says that he cannot give a subnet bigger than /30 because he fears that the ISP edge router ...
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1answer
484 views

ARP Connectivity on cisco small LAN

I feel so lame to have this doubt, so there is the question : Why do I not have connectivity ? The case is simple, I have configured the topology and have connectivity between each PC and respective ...
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1answer
739 views

Router is continually broadcasting the same ARP request, with the exact contents

I hope the question is clear and that this is correct place to post the question. My router is broadcasting the same ARP frame over and over (once every second). It's probably not a big deal, but I ...
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1answer
112 views

ARP issues across MAN

We have a large area MAN provided by a local cable company. Each location has a cable modem that connects directly back to a central location, i.e. it doesn't cross the internet, it is a private ...
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2answers
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How can I configure permanent arp entries on Red Hat Enterprise Linux?

I'm configuring a Red Hat Linux server which will be sending UDP packets out but never receiving ARP responses. So a static ARP entry is required. The obvious way to do this is. arp -s 10.0.0.1 ...
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2answers
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NIC Teaming with Broadcom on HyperV 2008 R2

I have a HyperV cluster made up of 3 hosts. Each host is connected to both of my Nexus 5548 switches running in an etherchannel. LACP on the switch and NIC teaming using Broadcom 802.3ad on the server ...
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2answers
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Neighbour table overflow on Linux hosts related to bridging and ipv6

Note: I already have a workaround for this problem (as described below) so this is only a "want-to-know" question. I have a productive setup with around 50 hosts including blades running xen 4 and ...
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1answer
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Why is a ping response being sent to the wrong gateway?

In a previous question, I was trying to determine why my OpenVPN clients could not ping the server LAN, even though the server LAN could ping the clients. Having investigated this further, I ...
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1answer
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Ubuntu Linux - two interfaces, same subnet, different vlan - MAC/ARP issues

I'm attempting to setup a server that needs to have interfaces on the same IP subnet, but different VLANs: eth1.102 Link encap:Ethernet HWaddr 00:50:56:b1:00:0f inet addr:10.1.1.6 ...
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2answers
110 views

What happens if two machines respond to an ARP “who is” request?

I am only recently learning about the nuances of networking, but if a malicious user responded to an ARP "who is" when they should not have, what happens?
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2answers
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2 NICs 2 IPS same subnet

I am setting up a SUSE 11 box that has two NICs: eth0 - 192.168.10.150/24 - 00.0C.29.DC.10.CA (MAC) eth1 - 192.168.10.151/24 - 00.0C.29.DC.10.DE (MAC) I need both in the same subnet since they will ...
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3answers
3k views

Strange linux neighbor cache entries (whole-world-is-link-local syndrome) (linux 3.0.0-16)

On absolutely standard ubuntu-server linux distro running only BIND cache, sometimes i see non-link-local ip addresses in the arp/nei table and there is no way to communicate with those entries After ...
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1answer
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Linux: arp cache timeout for non existent hosts?

In Linux, is there a different arp cache timeout for non existent hosts? At my router, 192.168.0.1, i'm seeing aprox. 8 new entries every 10 seconds for an IP that has been down for a long time. ...
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1answer
435 views

Detecting network state with arping

I am developing system for detecting network actual state. One part is to get all IPs and their respective MAC addresses. Right now I am using arping in DAD (Duplicate Address Discovery) mode. I send ...
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2answers
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Machine always responds to 192.168.1.2 IP address, which is not set on the machine

UPDATE BELOW: UPDATE 2 BELOW: FINAL Solution I have a brand new HP EliteBook notebook 8560p running Windows 7 64bit. I plug it into a small Dlink di-604 router, it is currently configured with DHCP ...
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2answers
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Where is the arp_cleanup_interval variable in Solaris 11?

In Solaris 10 I can configure (and audit) the arp_cleanup_interval variable using the following command: $ ndd -get /dev/arp arp_cleanup_interval 300000 In Solaris 11 (Express and Release) the same ...
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1answer
2k views

Why does a PXE-booting VM aggressively seek Reverse ARP?

Reverse ARP is.. well, pretty much dead, as far as I'm aware? One of the great Internet success stories in killing off a protocol? It's been deprecated in favor of BOOTP (and later, DHCP) for almost ...
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1answer
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How to setup a static multicast ARP entry with Cisco SG300?

We're running a Microsoft NLB cluster in multicast mode as a loadbalancer. Using our old Cisco IOS switches we propagate access to the cluster to our branches using a static ARP entry in the core ...
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2answers
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How do I prevent excessive ARP requests sent from Windows Server 2003?

OK, I've scoured the 'net already for possible solutions and have found none. Maybe you guys can help me. I have a Windows Server 2003 setup, with a fixed IP on a routed LAN, standard /24 network. ...
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1answer
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Linux storing arp cache entries using wrong interface

I'm trying to get two virtual machines (running CentOS) to talk to host (Ubuntu 10.04) using VDE and the outside network. So far I'm running into an ARP issue. On Host I have a physical eth0 and a ...
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1answer
226 views

Adding entries for incoming arp requests to ARP cache?

Given a host A und B within the same broadcast domain whose ARP caches are both empty, under what circumstances would B add an entry for A to its ARP cache when replying to an incoming ARP request ...
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1answer
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Many ARP requests in TCP dump?

I have been experiencing very slow upload speeds on my cable network lately. I ran a tcpdump and found many ARP requests. I'm not sure what process they are coming from, but could this be related to ...
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1answer
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Why is my Nexus 5548UP not adding ARP entries for the trunk to a 2960S?

I have a Nexus 5548UP trunked to a Catalyst 2960S. I have verified that spanning tree is working. I explicitly made the 2960S the root bridge for all VLANs as a temporary measure since it is trunked ...
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0answers
329 views

Windows Server 2003 DC sends Gratuitous ARP requests with wrong IP

Hello and excuse me for my English please. ;-) Two server seems to be involved with this problem. Our DC (domain controller, 2003) an the VMware VC-Server (2008 R2). After capture "some" network ...
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3answers
3k views

Should a Dell 5424 switch have an arp entry for every machine connected to it?

I've got a Dell 5424 with about 20 machines directly attached to it. I did a ping sweep of my network (and got answers from all 20), then went to the CLI of the switch and did show arp. To my ...
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2answers
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ARP reply vanishes from br0 to tap0 using OpenVPN in bridging mode

I have setup a linux box (on an esxi5) which acts as an OpenVPN server. the server is configured to use bridging for the clients, which essentially works, with one exception. If the client pings some ...
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2answers
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linux routing bug?

I have been struggling with this not easily reproducible issue since a while. I am using linux kernel v3.1.0, and sometimes routing to a few IP addresses does not work. What seems to happen is that ...
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3answers
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Why need to send ARP to ask for MAC address when IP address is already unique? [closed]

In the usual networks, since every host has a unique IP address recognised among the stations in the network, why is a MAC address still necessary? Suppose a station A wants to send to Station B. ...
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1answer
726 views

arp requests are sent continuously and my linux machine disconnected to the world [closed]

I have the following problem and really need your help I'm implementing a small server to receive request from client on port 18999(just sample) using TCP socket. When I tested my server by using a ...
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1answer
277 views

Which NIC have the IP address?

If I have two NICs where I know the MAC addresses. Without logging into the server, how do I figure out which have the IP address 10.10.10.10? Can arp somehow be used for this?
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postgres fallback to standby server, switching ip address, clear ARP cache

I'm using a hot standby server for my postgres database. I've assigned a virtual ip address to the server. In case of a failure I'm switching the virtual ip from the master to the hot standby server. ...
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2answers
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ARP requests, etc.

I'm trying to run arp spoofing on a network. I've been working on this for about a week, and all the information I find is dated year 2000-2001. My issue is, after testing a script that uses ...
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1answer
262 views

ARP discovery on multiple subnets

I have an unmanaged switch which serves traffic belonging to different subnets. Lets say these are the subnets: 192.168.0.0/24 192.168.1.0/24 192.168.2.0/24 And few more subnets which I am not aware ...