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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Protection from ARP spoofing

I'm running Linux and I know my gateway will always be 192.168.1.254 with MAC address aa:aa:aa:aa:aa:aa. Is there any way I can instruct my machine to only ever use this MAC address for the gateway ...
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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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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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arp who-has requests view vlan isolated different addresses (single NIC)

I have debian hosts which are connected through trunk port on 5 different vlans. But this host respond to arp "who-has" requests of all of their differents ip. I wish understand why ... Here the ...
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530 views

Windows 7 Requires ARP for UDP?

Seems like my Windows 7 box (with 2 NICs if that's relevant) requires an ARP response before it sends packets to a certain IP address. The specific context I'm in is running a TFTP server (TFTPD32). ...
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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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262 views

Multiple VLANs - how Linux / Debian process packets

I can't find answer about how linux processes incoming packets from different VLANs, that do not belong to a subnet assigned to a VLAN. Imagine this situation. On Linux machine with the following ...
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330 views

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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765 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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arp --detete is not deleting an entry; merely marks entry as “incomplete”

I run arp --delete and it leaves the entry but it's simply marked as incomplete. I expected --delete to entirely remove the entry. Does anyone understand what is occurring here? $ sudo arp -avn ? ...
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336 views

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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1answer
440 views

Switch CAM table and ARP messages

When the switch CAM table is empty and it receives an ARP message, does it add to the CAM table the source MAC address ? In Packet Tracer I saw that it does add it, but I read in some book that the ...
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54 views

What network traffic when ethernet plugged in [closed]

So in a general sense (e.g. not windows, linux specific) what network traffic is generated when I first boot up/plug in a network cable. Basically: Detect DHCP server Pull an IP Address from DHCP ...
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233 views

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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591 views

Dynamic ARP Entries turning into Static ARP entries

I recently acquired a client that has a strange ARP caching issue on one of thier servers. I have a server that will eventually start turning it's dynamic ARP entries into static ARP entries. This ...
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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 ...
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888 views

Arp request is not resolved

On my machine, I have assigned ip addresses for two interfaces which are connected through a cable. They are connected with 10G ports. When i tried to ping the two addresses, ping was not working. ...
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61 views

Server Core DNS Server in VSphere doesn't respond to ping and needs continuous arp clean

I have a VSphere installation hosting two Windows Server 2008 R2 installations. One of them is a complete install that serves as a DHCP server and that I use for administration. The other install is a ...
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5k views

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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139 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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1answer
463 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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1answer
429 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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848 views

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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987 views

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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1answer
457 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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211 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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1k views

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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805 views

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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219 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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1answer
816 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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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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279 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
1k views

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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929 views

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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198 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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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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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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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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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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403 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 ...