Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [arp]

For questions about Address Resolution Protocol (ARP). ARP resolves OSI layer-3 addresses to OSI layer-2 addresses.

0
votes
0answers
10 views

SDN network simulation [on hold]

I'm doing a research on ARP spoofing in SDN. I need to simulate this attack. Is there a way to create a virtual SDN and do the attack on it?
0
votes
0answers
36 views

Wireshark switch ping

I understand that a switch will broadcast to all ports if it doesn't have the destined destination in its mac address table but when I analysed a scenario in wireshark I got confused at what happened. ...
0
votes
1answer
18 views

How does a system know the local gateways MAC address for given IP address [duplicate]

Assuming you have the following network structure. Knowing the IP address of the WWW-Server, system A wants to send an IP packet. As I understand the destination MAC address has to be in the same ...
1
vote
1answer
43 views

switch wireshark arp

I connected 4 pcs to a switch, I used pc 1 to ping another pc(pc 3) and used wireshark on all the pc's. The one that sent the ping sent out an arp request and received 4 request and replies from the ...
2
votes
2answers
82 views

Please help me understand this simple arp request / reply - how does a router know an IP address without knowing the MAC address?

I am new to networking, I am using Wireshark on my home PC to learn about ARP. I understand that ARP is used to build the ARP cache, which correlates IP addresses to MAC addresses on a LAN. ARP ...
6
votes
4answers
1k views

Does every host on the LAN share the same ARP table, or do hosts keep them individually?

I'm just learning about ARP. I'm a little bit confused. My confusion is better explained in a scenario. Host A is communicating with Host B. Host A knows Host B's IP address, but not it's MAC address....
2
votes
1answer
61 views

MAC Table vs ARP

I understand that for a switch to learn a MAC address, if host A wanted to send data to Host B the switch learns host A MAC and places it in the MAC table. If it doesn't know where the MAC (for Host B)...
1
vote
2answers
63 views

How does a computer know IP address of a computer on another network

I was watching a video explaining ARP, which was explained really easily but I got confused when they said that Host A already knows Host D ip address which is on another network. Host A and B were ...
0
votes
0answers
12 views

ARP and OSI model layers [duplicate]

Is ARP Layer 3 or Layer 2 protocol? It is used to figure out destination MAC, which is a second layer address, however, it has the info about destination IP address, which is a third layer address, ...
2
votes
2answers
63 views

How does a router know the destination mac?

so if I send a packet from a host to another from the same network we know the mac address of both the source and destination. However if the receiver is in a remote network the destination mac ...
0
votes
2answers
21 views

What is the bridging decision when getting ARP request?

Setup: Assume I have 3 VMs. VM1 VM2 and VM3. VM2 has two interfaces, say eth1 and eth3. eth1 is connected to VM1 physically and eth3 to VM3. I create a bridge on VM2 using brctl with eth1 and eth3. ...
0
votes
2answers
75 views

Why we need ARP when each device has its own IP address?

I don't really understand Address Resolution Protocol (ARP). Why we need ARP when each device has its own IP address?
0
votes
3answers
117 views

If ARP uses broadcast, can I find out MAC-Address AND IP with it?

I have a peripheral device, connected via Ethernet to my Ubuntu. I would like to find out its IP, and untofetunately no it is not cached in my ARP table. ARP broadcasts the messages to every ...
1
vote
1answer
129 views

How does ARP work on multilayer (Cisco) switches

I'm going to develop an example scenario here: There is a computer that is connected to an interface on the switch that has been assigned VLAN2 and another computer on an interface that has been ...
3
votes
1answer
140 views

Cisco ARP cache rewrites?

I know that the Cisco's default ARP entry expiration is 240 minutes, however how does the ARP table mechanism work when a different MAC address is seen using the same IP? In other words, if I move ...
3
votes
1answer
93 views

To what address does ARP reply in the presence of MAC masquerading

The ARP packet has a duplicate of the sender/destination hardware address. Theoretically, you could have a case where a device sent Layer2: From AA:BB:CC:DD:EE:FF To FF:FF:FF:FF:FF:FF Layer3: ARP ...
1
vote
2answers
30 views

How can subnets not fulfil symmetric property?

While studying Internet Protocol, I came upon the following example of two devices: Device A: IP address: 10.1.1.1 Subnet mask: 255.255.255.0 and Device B: IP address 10.1.1.200 Subnet mask 255....
2
votes
1answer
40 views

Do the intermediate nodes learn a MAC address in ARP?

my doubt is about the ARP protocol. I know the procedure: if a host wants to know the MAC address of another sends a broadcast frame and the destination answers with its MAC. However, if an ...
0
votes
1answer
30 views

Does bridge store ARP reply information?

In above picture, D is sending packet to E and bridges B1,B2,B3,B4 have no forwarding entries. Firstly, D sends packet to B3 nad B3's forwarding table is updated. B3 sends packet to B2. Therefore, B2'...
2
votes
1answer
90 views

Cisco Nexus 5672, not showing ARP records for VLANs

I have a Cisco Nexus 5672 which only lists the management VLAN ARP records, when doing show ip arp vrf all yet we have many VLANs on this switch, but it doesn't have a IP in all the VLANs, only the ...
3
votes
1answer
222 views

ARP Table Entries

I tried to look into different ARP topic but none of them helped me. It may be a ridiculous question for many of you, please have mercy on a poor noob studying for CCNA :) This been said, here's the ...
3
votes
1answer
225 views

How can I match conditions when I show arp?

In my Cisco Router I check the arp: Router>show arp Protocol Address Age (min) Hardware Addr Type Interface Internet 192.168.1.1 - 0001.42D2.AE01 ARPA ...
2
votes
3answers
147 views

Ping command through network

I have been trying to understand how and what tables are populated ( if they are clean at the start) when a ping command goes through. Lets say I have this network: I want to send a ping command from ...
1
vote
1answer
52 views

Why does arp request get broadcast even though it knows the ip address of receiver?

Since the arp request wants to know the Mac address of an ip address which belongs to any one device what's the purpose of sending a broadcast Anyway even though we know only that ip address device ...
0
votes
1answer
115 views

ARP requests from outside the network [closed]

I need help understanding an ARP Storm PCAP I'm currently studying. My understating is that routers will strip layer 2 info. Therefore, an ARP request frame will not go through a layer 3 device (...
1
vote
3answers
85 views

How did one go from IP to MAC in classful networks?

This is more of a question asked out of curiosity than for practical reasons, but it's bugging me, because it might point to a lack of understanding elsewhere. Back when classful IP addresses were ...
1
vote
1answer
315 views

How to capture ARP Reply packet from all hosts in the network?

How can I capture ARP reply packets from all hosts that are connected in the network? I've tried wireshark premicious mode but it only capture ARP replies from gateway.
0
votes
2answers
116 views

How can i monitor ARP packet on WiFi network?

I want to monitor packet in my network. It said that ARP packet request broadcasted all over network. But why i only see my arp request packet and reply packet to the gateway?
6
votes
3answers
931 views

What is the characteristic of spoofed ARP packets?

Hi what is the characteristic of spoofed ARP packets? I want to know how to detect it but before that I have to know how can I call a packet a spoofed packet. I hope you can help me thank you.
1
vote
3answers
234 views

Dynamically learned MAC address seems to never expire

I have a user getting error "No logon servers available" at login on a Windows machine. Topology is this: R1--SW1--IP phone--PC1 I cannot ping PC1 neither from its gateway R1 nor from SW1 (access ...
1
vote
1answer
59 views

What does “delta” stand for in arpwatch?

I've just set up Arpwatch on my pfSense machine and started getting emails about flip flops in my network. As the network is quite big, I understand that the flip flops indicate that a certain IP-...
0
votes
2answers
362 views

How to force users on my LAN to use a specific DNS server using ARP poisoning?

I'm attempting to force all hosts on my LAN to use a specific DNS server to filter certain material, however I'm running into problems. I've had problems in the past trying to configure my router's ...
1
vote
2answers
63 views

Why ARP need ARP cross LAN request?

Why ARP need ARP cross LAN request? When I am reading a document: You see the host A(10.1.0.1/8) send ARP Request for 20.2.0.1/8's MAC address. In general, the ARP request is for MAC address in the ...
2
votes
2answers
604 views

Why would pfSense ignore arp requests?

I'm configuring pfSense 2.4.3p1 as a transparent firewall. It's running in virtual machine with two vtnet paravirtualized adapters: WAN (vtnet0) connected to a 'far-side' network containing the ...
1
vote
3answers
106 views

Why do clients request a MAC via ARP, if the router knows the local LAN's MAC addresses already?

If I have an infrastructure type network, why does a local PC send out an ARP request for a MAC? Doesn't the router know the MAC addresses already, since it is using at least Layer 2? Does it do ...
5
votes
3answers
321 views

How to prevent IP conflict when using VRRP

We are currently using VSRP (Layer2/3) where we have a single IP as the gateway per VLAN. We are considering moving to VRRP (Layer3) which requires 3 IPs, 1 virtual and 2 real ones. This means that ...
0
votes
1answer
79 views

Iterative queries of a default DNS server

I have just started to study networks and I have a confusion about what happens when a default DNS server does iterative queries to other DNS servers to resolve a name in an IP address. I am very ...
1
vote
1answer
79 views

Network interface issues an ARP request to get the MAC address of an actively used gateway

My network interface actively uses a gateway to send IP packets to other networks. There is already an ARP entry in the cache for the IP/MAC association for the gateway. Is it normal that my network ...
3
votes
2answers
297 views

How does the ARP table work in case of the Gateway Router?

Suppose I am a host, I understand how ARP works in case I address an IP within my subnet. For each IP address there is a corresponding MAC address, and the owner responds to my broadcast ARP query. ...
1
vote
0answers
56 views

Same mac addresses for all the IPs [closed]

So I'm on a public wifi network and I'm trying to do intrusive testing. The issue is that while doing arp scan all the IPs are returning the same mac addresse.
1
vote
1answer
465 views

What are the key advantages and disadvantages of NDP compared to ARP?

So why they didn't use ARP in IPv6? is there any real benefit of doing this? what are the key advantages and disadvantages of using NDP instead of ARP? (In overall network performance, Security and ...
2
votes
1answer
193 views

Why would my router send an ARP request about a device that's already listed in its ARP cache?

I checked my Ubiquiti EdgeRouterX's ARP table and my laptop IP and MAC address were there. I then checked the DHCP lease and my laptop's IP address doesn't expire until tomorrow. I then ran ...
2
votes
3answers
1k views

If there's no response to the ARP request, will the host send to its default gateway?

Host A and B are on the same subnet. A sends ARP request(s) asking for B's MAC. For whatever reason, B doesn't respond. Will A either: Give up -- it can't reach B Send the packet to the default ...
3
votes
3answers
226 views

How to tell which one is the source IP and MAC address of the data being received?

I have to work with an FPGA module already running a code written by someone else. I have no access to the FPGA code. Now the setup is something like this:- FPGA is connected to the pc via ethernet ...
1
vote
2answers
116 views

Router ARP Table

I have attached the topology, PC0 and PC1 are in same network (192.168.1.0/24) PC0 send packet PC1 directly after arp resolution. So why router arp table shows PC0 and PC1 mac address. (Although the ...
1
vote
2answers
138 views

Which MAC should be used: device MAC or Interface MAC?

My L3 switch has ~30 interfaces. If you look at the output below there are two MAC addresses showing in the results of the show interface command. The hardware address is the same for all interfaces. ...
5
votes
3answers
7k views

What are the reasons for seeing an incomplete ARP?

As was mentioned in this post: The reason for seeing an incomplete ARP is that "An ARP request was sent for that address, but the host with that address is not up and running on the LAN, so there is ...
2
votes
0answers
103 views

Cisco: Routing issue between LANs [closed]

We have a project to create 3 offices, which are 3 different LANs where the configuration should be as follows: Each Office should have 1 printer, where the office is able to print They should be ...
1
vote
2answers
546 views

Gratuitous arp and unicast flooding

we have few 100s of access switches connecting to a core 10k in IRF. Here all our access is pretty much dumb does only L2 job. So what happens now is unicast flooding, technically MAC ages out, ...
3
votes
1answer
72 views

Question about diagnosis of ARP spoofing

Hello, I'm studying link layer and ARP Spoofing. While I was searching ARP Spoofing on internet, I found that being attacked by ARP spoofing can be found by checking whether there are duplicate ...