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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How do I poll the ARP table with an SNMP OID?

When you need to poll the ARP table of a device, conventional wisdom is to use ipNetToMediaPhysAddress or atPhysAddress; however, both of these OIDs are deprecated according to Cisco's documentation. ...
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174 views

Sender Information Not Cached on the Receiver During an ARP Request

I'm currently trying to get my head around more advanced networking concepts. The way I am doing this is by going on one of the servers I look after as a sysadmin and running network captures to see ...
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519 views

arp across subnets which devices can be detected?

i have some devices connected in the same physical network (LAN) but in different subnets. I want to detect them all with the ARP from my computer. My Computer is also in the same physical network but ...
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568 views

Update mysql database with arpwatch textfile database

I'm looking to keep arpwatch entries in a mysql database to crossreference with other information I'm storing based on mac addresses. I've manually imported the arpwatch database into my mysql ...
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Random and Selective ARP blindness in VMWare ESXi 4.1

We have multiple VMWare ESX servers spread out amongst our company, doing various tasks. One particular ESXi host is exhibiting very peculiar behavior. We detect it when our monitoring system ...
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Windows server sending constant ARP requests to offline devices

We have a Windows 2003r2 server which is sending intermittent ARP requests to several devices which are no longer on the network. The result of this is disruption to a PLC which is running over ...
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Network throughput issue (ARP-related)

The small college where I work is having some very strange network issues. I'm looking for any advice or ideas here. We were fine over the summer, but the trouble began few days after students ...
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537 views

Solaris Slow ARP Failure Unreachable Host

We have been experiencing slow timeouts for unreachable hosts is extremely slow. Recent testing in our lab shows it may be a delay reporting negative ARP lookups. Dumping traffic during attempts to ...
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249 views

Find IP address from a MAC address

Is there anyway to find the IP address of a MAC address using a command? I was thinking something like arping might work but can't seem to find much information on it.
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Failure to obtain IP with ARP over Wi-Fi with personal Wi-Fi router in client mode

I'm trying to connect a Samsung TV to the Internet using a TL-MR3020 personal wireless router in client mode. The TV fails to connect to the network. It sees the ethernet cable connected though. ...
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Arp requests with odd source IP go unanswered

I'm having a server with network connectivity issues that I presume come from issues with arp protocol handling. Let's say the network topology is as follows: network 192.168.106.0, netmask ...
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309 views

Proxy arp and 1:1 NAT

I have a Linux router with 2 NICs doing masquerade from network 192.168.0.0/24 to an ADSL router. users <----> NIC A [router] NIC B <----> INTERNET Now I'm experimenting with proxy arp ...
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arp -n responds with (incomplete) on the wrong subnet, can't remove it

context There are 2 servers: server1 - eth0 10.129.76.16 eth0.2 192.168.0.103 server2 - eth0 10.129.79.1 eth0.2 192.168.62.101 The 192.x.x.x addresses are connected to the ...
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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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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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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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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 ...
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922 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 ...
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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
372 views

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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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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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
305 views

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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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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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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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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863 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
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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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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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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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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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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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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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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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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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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
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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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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. ...
2
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1answer
504 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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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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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
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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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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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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 ...