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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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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Bad ARP Cache static entries

I have a weird issue that popped up on our network. Once or twice a week a user (it's always a different user) would complain about not being able to communicate to our Small Business Server 2003 ...
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Block ARP on Router

Is it possible to somehow block ARP on a home wireless network router? Basically I don't want the access point to forward ARP packets between clients. It would also be fine if the access point ...
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How is a TCP request routed from a virtual machine to an outside resource and back again?

Scenario: Computer A has a local ip of 192.168.1.100, which is running a VM inside of it. The VM now makes a tcp request to an external IP address (74.125.225.98). Could someone explain how the ...
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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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Is Windows Server 2008 R2 arp cache per user or per machine?

When running arp -a in a Windows Server 2008 R2 prompt, will the returned entries cover connections from all users logged on to the machine or only the current?
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257 views

Can a duplicate computer name be known before attempting to join the domain?

Techs in the field are deploying windows 7 pcs onto a domain. They complete one entry screen, which should give them a unique computer name. However, they are human and end up giving the pcs the ...
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64 views

Can arping by IP but not MAC address

I have an interface that I can arping to by its IP, but not its MAC address: # arping -i eth2 10.10.0.153 ARPING 10.10.0.153 60 bytes from 02:68:b3:29:da:98 (10.10.0.153): index=0 time=81.062 usec 60 ...
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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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132 views

How to convert proxy ARP setup to IPv6?

My company has a router/firewall deployed with the "common" Proxy ARP setup: it sits between some servers and the ISP gateway, and intercepts all the packets with proxy arp, so that it can apply both ...
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880 views

Broadcom Advanced Control Suite 4 on a PowerConnect 2848 making router (ASA5505) throw ARP errors when TEAMING (different MAC addresses from same IP)

For some reason the Broadcom Advanced Control Suite 4 seems to be a little buggy OR I have not configured something correctly. I have 4 Gb NICs and I team 3 of them to make a virtual adaptor... ...
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537 views

Cisco ARP table: determine directly connected devices

I have a Cisco switch and a big list of servers on the network. I need to determine what servers are connected directly to that switch. Will searching for the MAC address of each server in the ...
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202 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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190 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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394 views

Windows Domain controller ARPing for 169.254.0.0/16 addresses

I've been doing some sniffing on my company's network to try to clean up some of traffic and have noticed that one of our Server 2008 Domain Controllers is sending out ARP's every second or two to ...
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Physical switch not learning MAC address of virtual machines

I have a virtual environment running vSphere 5.1. I have two ESXis with a vDS between them. There is, for the purposes of the discussion, just one portgroup on that vDS configured to use a VLAN. The ...
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748 views

Using arpwatch to backtrack proxy access ip to eap-tls certificate

In my network I am using eap-tls authentication (machine certificates) for clients. Those clients are using a squid proxy to access the internet. The proxy is logging the request to the access.log. ...
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arp failing after heartbeat failover occurs

I have an LVS based load balancer which has been working just fine. It runs on two servers using heartbeat to provide failover. I've added support for a second IP range to the system, but when the ...
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258 views

How to prevent response to who-has requests on virtual eth interface?

we use small embedded X86 linux servers equipped with a single physical ethernet port as a gateway for an IP video surveillance application. Each downstream IP cam is mapped to a separate virtual IP ...
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101 views

iptables arp compare and execute

EXAMPLE: iptables :internet - [0:0] -A internet -m mac --mac-source 48:5D:60:FC:29:B0 -j RETURN COMMIT [root@localhost:~ ] $ arp Address HWtype HWaddress Flags Mask ...
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Move IP from one server to another without disruption

I have an internal DNS server running on a VM. I've rebuilt the server from scratch in a new VM, and I want to cut over from the old to the new at some point. In order to do this, I'll need to take ...
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163 views

How to capture arp table when using network bridging?

I have a computer with 2 NICS that are bridged and I need a means of distinguishing between machines connected to eth0 from machines connected to eth1. I was hoping to use something like the "arp -a" ...
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561 views

Permanant ARP entries become Unresolved

We have a solution where a number of Solaris servers are in a private VLAN and no arp proxies exist in this VLAN, so to reach neighboring servers we must add static arp entries. Each other server in ...
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120 views

How to decrease linux box arp response?

I had known that I can not stop arp flood from others, so I wonder to know how can I decrease the response times per second, so that my cpu wont cost too much for arp flood, any tips?
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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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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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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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216 views

Pinging an interface of same network on same host not working

I'm setting up a very basic IPS test, and wondering if an interface on a host pings an interface with a different IP address (of same network) on the same host, will it reply? Will it respond to ARP ...
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447 views

Hardware won't respond to each others ARP requests

I have two pieces of hardware (embedded devices) that I have setup to communicate via TCP over Ethernet in a client/server fashion. The topology of the network is as follows: ----- | S ||=|== Debug ...
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How are ARP reply collisions typically handled?

If a node receives multiple, conflicting ARP replies, what happens?
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'arp authorized' alternative

Is there another way besides arp authorized command on a cisco router to prevent users from setting static IP addresses on their computers and getting access to the network? Essentially, limiting ...
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linux not replying to an arp request

I am running linux 3.14 on a system with 2 interfaces. on the first interface, i can access our local network. on the second interface, arp packets come in but linux doesn't send out reply. is it ...
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Broadcom NICs, Cisco ASA and ARP request collisions

First of all I am sorry for my english mistakes. Help me please to solve the problem with ARP request collision incidents. I have IBM BladeCenter E chasis with blade servers are installed in this ...
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Directed ARP requests do not arrive at bridge interface

I'm baffled by the following weird bridge/arp behavior under Linux. It somehow seems to filter directed ARP requests, whereas it should forward them to the other end of the bridge. To test, I run the ...
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410 views

arp problems with transparent bridge on linux

I've been trying to secure my virtual machines on my esx server by putting them behind a transparent bridge with 2 interfaces, one in front, one at the back. My intention is to put all the firewall ...
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266 views

“Destination Host Unreachable” and ARP returns no addresses over LAN

I am currently trying to setup LAN over two machines with a network mask of 255.255.255.0 however I am receiving the following message when trying to communicate between them both; [root@alpha ~]# ...
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Duplicate entries in switch ARP table

A server is showing twice or more on my L2 switch ARP table Same IP address, mac address, and ethernet port. What could be causing this? Thanks
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Understanding ARP traces during OS load

Consider the following ARP packets captured while a unix machine was booting. From the packets I understand that this machine whose MAC address is 00:22:22:22:22:22 is requesting information about ...
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1answer
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ARP response is not present on the other port of linux bridge based on ubuntu 13.10

I recently build linux based bridge for packet monitoring purpose, but there is BIG problem. the environment is, overall env. target of monitoring is VMs on vSphere. two vSwitches are configured ...
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ARP Tables on Windows vs Linux

I noticed on Windows Server 2008, Windows Server 2008 R2, and Windows 7 that IP multicast groups joined by a computer are recorded in the ARP table as static addresses automatically. However, the same ...
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VMWare ESXi 5.0 Networking Issue

I have an issue with 2 new ESXi hosts. OS - ESXi5.0 Custom Dell ISO patched up to Build 1024429 DELL R820 with 1G network 2 ports from integrated MB NIC(Intel) connected to 2 juniper switches, one is ...
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Can you SNMP poll the ARP table on Cisco ACE?

I'm trying to get a MAC <=> IP mapping from a Cisco ACE. Unfortunately according to this table, while it supports IP-MIB the ipNetToMediaTable and ipNetToPhysicalTable subtrees are not supported. ...
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Keepalived, Junos, and ARP caching

I'm trying to configure an active-passive stunnel setup, with the aid of Keepalived, for a public IP address at our company datacenter. I would like to know if a router or switch reconfiguration is ...
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434 views

Broadcom NetXtreme II GigE Teaming Does Not Use Unique MAC, Causing Collisions

I currently have a new Dell server on my local (inside) network that I have setup to use three of the four nics to create a team. Examples below. NIC_1 - mac: 000000000001 - ip: n/a NIC_2 - mac: ...
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arp reply is not processed

My eth0 interface does not process a legitimate arp reply. When I try to ping a host, I see arp request and reply with tcpdump from the host I try to ping from, but ip neigh says that there is a ...
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333 views

Cannot ping any machine on local network (embedded linux device)

I have an embedded linux installation (custom built using buildroot, uClibc and busybox) and I am unable to ping any machine on my local network. My /etc/network/interfaces file is as follows auto lo ...
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Pinging between hosts through Layer2 tunnel fails

I have some serious problems with my newly setup network with a Layer 2 VPN tunnel. I draw a little diagram to show the simple version of the setup: The green lines are through the VPN, the blue ...
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openvpn connects but does not work until server pings client

I'm trying to configure a connection using openvpn from a windows 7 client machine to a linux host. I'm using openvpn in the traditional routed mode using tap devices, and the configuration I'm using ...
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stop arp poisoning on a 5448 powerconnect switch

We have to disable arp poisoning on our dell 5448 switch. Right now it has all our production machines running on it and I'm not a networking guy at all so I don't want to run a command that will ...
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What is the meaning of the QUEUE in arptables

I use the nfqueue target of iptables in order to get packet to the nfqueue and do some business rules on them. iptables -A INPUT -p tcp -j NFQUEUE --queue-num 0 I need to do the same on arp reply ...