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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arp poisoning and mitm protection [closed]

I'm trying to understand mitm by arp poisoning. To do so I'm practicing on the network I manage: attacker : IPA victim : IPC gateway : IPG I use nighthawk, and kali linux (via virtual box). I can ...
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309 views

Keepalived failover not working for Static NAT target behind Cisco ASA

I've got a Cisco ASA[0] with a pair of Linux boxes in the DMZ running Keepalived and HAproxy acting as a load-balancing failover pair for another pair of Windows servers, also in the DMZ. I'm ...
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195 views

I am not able to connect to my server from my leased line internet connection

I am having some troubles connecting to my Fedora server from my static IP ISP connection. Usually I can ping that server with no problems. But other times it just gives me timeout responses. When ...
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196 views

Solaris 10 invalid ARP requests from 0.0.0.0? Link up/down every hour or 2

The guys at the data center where I'm hosting a server running Solaris 10 are telling me that my server is making a lot of invalid arp requests. This is an example of a portion of what was sent to me ...
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69 views

ipwatchd detects non-existing conflict?

Ipwatchd is telling me about a conflict that I just do not understand. As far as I can tell, there is no conflict. Am I reading the message wrong? It's a Xen machine with the following network ...
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91 views

Can ARP with IP aliases on Windows be made to behave like on Unix?

On FreeBSD, when I have one interface with two IPs: ifconfig nic0 192.168.0.1 netmask 255.255.255.0 ifconfig nic0 alias 192.168.0.2 netmask 255.255.255.255 If I ping the alias, if the host I'm ...
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486 views

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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5answers
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Bypassing VLAN with known MAC address

I am evaluating subneting our network with a Layer 2 switch and VLAN. From what I know, VLAN only works on broadcast domain, and if I know the MAC address of a remote computer on the same switch, I ...
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3answers
1k views

Switch behavior on unicast packets when the destination is unknown

Please let me start by saying I am no network expert, I am a programmer who does a fair amount of L3/4 programming. My question is that when a switch receives a packet with a destination MAC that is ...
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3answers
725 views

Best method and tools for local IP scanning [closed]

I’m starting to administer a small but confusing und badly documented local heterogeneous network (mostly Windows workstations, printers, laboratory equipment, etc. and one Linux/Samba Server) ...
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2answers
937 views

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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2k views

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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4answers
2k views

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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2answers
285 views

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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2answers
811 views

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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2answers
228 views

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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2answers
411 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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1answer
76 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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1answer
1k 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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2answers
475 views

iPads cause arp-scan duplicate reports, why?

I have a situation like this: Isolated Gigabit Ethernet LAN with a handful of Linux boxes and Macs on it Airport Extreme wireless access point is also connected to the LAN Two iPads talking to the ...
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1answer
298 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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2k 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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2answers
235 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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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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2answers
731 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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2answers
2k views

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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1answer
777 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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2answers
1k views

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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1answer
274 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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1answer
59 views

Why ARP cache is not emptied as I except it to be?

I'm trying to empirically test the time an entry stays in the ARP cache table. This time seems to be defined by /proc/sys/net/ipv4/neigh/default/gc_stale_time file and by ...
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2answers
37 views

Arp request for a non-existing host in a local network

I'm wondering why I get the following result : if I try to access a non-existing host on my local network, for instance using the command ping, I see with the tcpdump arp command that there is every ...
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1answer
137 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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1answer
95 views

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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2answers
306 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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1answer
870 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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1answer
133 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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1answer
693 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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1answer
1k views

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
2k views

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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1answer
246 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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1answer
534 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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1answer
1k views

How are ARP reply collisions typically handled?

If a node receives multiple, conflicting ARP replies, what happens?
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1answer
341 views

'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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0answers
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Arp reply on behalf of another devices on Linux

There are devices on a network that don't support ARP (let's name them NARPs) and a device that supports ARP, running Linux (lets' name it LX). LX knows the IP and MAC addresses of NARPs. What is ...
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Two arp responses mysteriously show on IOS 8.3 [closed]

Here's my problem, maybe you can shed light on this, any help is appreciated more than you will ever know. I've been being targeted for a few years now and am having this ARP problem on my iPad Mini ...
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1answer
227 views

How to troubleshoot internet unreachable periodically through firewall

Periodically the internet is unreachable on my network, sometimes for 30+ minutes. After testing a direct connection to our modem, I realized this was not a problem with our ISP but the network ...
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2answers
806 views

Linux is sending ARP requests to hosts in other subnets?

Setup Host B <--> Router <--> Host A Host A: IP = 192.168.1.10, Net = 192.168.1.0/24, VLAN = 1, Default GW = 192.168.1.1 (Router) Host B: IP = 192.168.2.10, Net = 192.168.2.0/24, VLAN ...
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131 views

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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208 views

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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1answer
231 views

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 ...