Questions tagged [arp]

Questions pertaining to ARP (Address Resolution Protocol) a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address.

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arp -a returns only one device on Kali Linux?

I'm running a Kali Linux live USB. I recently was unable to connect to my Wi-Fi network, but I found a Wi-Fi adapter that let me connect to my network and use the internet without experiencing any ...
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Virtualbox NAT network not showing in Linux

I am currently Running a Bare Metal Kali with Virtualbox installed on it to the run Kioptrix Level 1. I created a NAT network in preferences with the default recommendations. This did resolve an ...
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ARP Entry OPENWRT Not Permanent

I am a bit of a networking noob right now. I am currently trying to get WOL(WOW) working using ARP Entries. Wake on Lan will always work with the configuration i am using right now, sending a magic ...
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How to reset the firewall configuration in a persistent manner?

Internet works, ping 192.168.1.4 which is for sure of an Android device does not. I believe it is an issue of the firewall programs. $ ping 192.168.1.4 PING 192.168.1.4 (192.168.1.4) 56(84) bytes of ...
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Parallel SSH to 500 docker containers stalls: ksoftirqd to blame?

Answering How to SSH to over 2000 nodes? I discovered the following: Running 500 parallel ssh to 500 servers is no problem if either: the servers are not on the same LAN (i.e. they are routed through ...
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Couldn't arp for host, Kali Linux

I am currently learning the basics of cybersecurity and I am trying to follow the following tutorial on ARP spoofing. I am using kali linux on a VirtualBox VM on my Windows pc to redirect my windows ...
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ARP: are probe packets to 0.0.0.0 target legal?

I have a LAN segment of 'dummy' devices connected via L2 switch to a 'smart' gateway. The port they are connected to is a trunk port. The devices don't know the VLAN ID, and thus needs to discover it ...
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Is it possible to send ARP request from another NIC

Suppose I have two NIC on server1 and two NIC on server2: NIC0 of server1 connected to NIC0 of server2; NIC1 of server2 connected to NIC1 of server2. NIC1 doesn't support ARP protocol(some specific ...
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How does arp works in IPV6?

In my project, I have a scenario of replace node with IPv6 environment When I assign one IPv6 address to node1 lets say xyz IP. By some reason if node1 goes offline, I will need to bring all services ...
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Why does an IPv6 neighbour router status become STALE? How can I avoid it?

I have a VM on a host with bridged networking (hence, with its own MAC address). Both host and VM run CentOS. Their network is managed by simple /etc/sysconfig/network-scripts/ifcfg-enpXsY files. ...
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gateway sends packets (L3) without data link layer (L2) connection

pretty straightforward question: #tcpdump -i wlp2s0 [..] 16:33:37.328154 IP 185.29.43.134.https > achille.43692: Flags [FP.], seq 2980347197:2980347221, ack 988779763, win 63, options [nop,nop,TS ...
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Delete illegal router from network

I have a default gateway with IP address 192.168.1.1 and MAC address 5c:77:76:6e:0d:7b. It is my only wi fi modem router from which I receive internet. But in input nftables logs I saw another one ...
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arp cache changes causing network interruptions (point-to-point gateway)

I have installed Proxmox on a virtual machine and am attempting nesting (vm within the vm) but am having some issues getting the network to work correctly. Due to the host having MAC filtering I am ...
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2 votes
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How to filter ARP-Requests with Nftables using a Raspberry Pi as AP (using hostapd)

I´m trying to filter ARP-requests coming from certain IP-addresses in my network. I tried : table arp filter { chain input { type filter hook input priority 0; policy drop; ...
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3 votes
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nftables Error: syntax error, unexpected saddr

I wanted to add the rule arp saddr ip 192.168.2.1 counter accept to my Nftables firewall. When reading the config-file with sudo nft -f /etc/nftables2.conf, I get the error-message /etc/nftables2.conf:...
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How does arp_process() replies to the right device?

Looking at Kernel source code I see that when processing ARP request the net_device is retrieved right from the skb, and then seems like the reply is sent to that device (arp.c#L679): static int ...
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how to verify that Gratuitous ARP disabled in a Linux server?

Problem: I need to verify if Gratuitous ARP is disabled on a Linux server in the configuration files.
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Arp Reply With Wrong IP - Ubuntu 20.04

This system is Ubuntu 20.04. It has a disabled wireless interface. It uses an onboard Ethernet port. I have a machine that is IP'd 10.0.0.142. It replies to pings on the local network at 10.0.0....
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Clients cannot connect to each other on WLAN. No reply on ARP requests

I have install a WLAN with an access point which connects the clients to the internet. At first all seemed to work correctly until I noticed that the clients can not communicate with each other. Here ...
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How to know on which LAN a machine is connected?

I have two LANs (192.168.1.0/24 and 192.168.2.0/24) linked by VPN. I have one machine (RPI3b+) that I can be connected on the first or the second LAN (I move it). How can I know where is the machine ...
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Identify all (arp) devices on network regardless of ip

I have a miss-configured device on the network where I don't know its IP-address. However since I do know all other devices I want to lookup its IP by using arp. Consider the IP might be on an ...
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How set MAC address filtering on linux?

I need to block any incoming connection from a MAC address different from a specific one (which is static and well known). This MAC address should generate only non-IP connection: this is the reason ...
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18 votes
7 answers
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Find the IP address of a newly-booted Raspberry Pi

I've attached a Raspberry Pi running Ubuntu to my home network with a cable. It is booted up and connected to the network. The Pi has no keyboard, mouse, or monitor. If I know the IP address that was ...
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Why is the server accepting connections after disabling the network interface?

I've googled around and executed other commands (I had left here only the ones that I think are more useful). Most searches pointed me to explanations about how to shut down/up interfaces and no hints ...
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Machine replies to "arp_requests" for internal addresses even though "net.ipv4.conf.<intf>.arp_ignore" is configured to disable this

I current have a node with an interface connected to the internet (through a VLAN). I will refer to these as eth0 and eth0.100, with the latter being the VLAN interface in the machine. I preemptively ...
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set the router's static mac address via isc-dhcp-server

Is it possible to set an ip with its relative mac address so that the clients (during the DHCP request) in addition to receiving the various data, will also directly receive the mac address of the ...
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arp doesn't run in script when run through crontab

I have a specific script that gets the IP address of a particular MAC. For this it uses arp, and it works correctly. The problem comes when I Program a crontab to run that script; it works fine and ...
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forwarding ARP reply on bridge device

This is my network: [laptop A]~~~~[ddwrt1]~~~~[ddwrt2]----[desktop B] | +--[desktop C] The ddwrt2 is a wifi router running in client bridge mode connecting to another ...
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ARP table does not populate if computer has two IPs on same inteface

I have three devices connected to a simple switch. All of the three devices have two IP addresses: one static (172) and one from the DHCP server (192). Computer A: 172.16.0.1, 192.168.0.1 Computer B: ...
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ARP Ping to one linux machine throwing No address associated with name

We are trying to use ARP (arping) to reach one linux machine, it throws following error: exec failed: 1: \S Kernel \r on an \m !!!WARNING!!! ###########################...
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2 votes
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arptables-nft persistence

Introduction This is on Debian Buster with kernel 4.19.0-6 I've installed iptables-persistent and netfilter-persistent versions 1.0.11 and added a basic rule to arptables-nft to block all LAN ...
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gc_thresh kernel config issues

We were having problems with kernel logs in our datacenter: arp_cache: neighbor table overflow! It was related to all of our servers having consul on them using gossip protocol and "flooding" the ...
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3 votes
3 answers
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Parse command arp -a for only ip

I need to parse the command arp -a to get only the ip of the device. Right now I have arp -a | awk '{print $2}' | head -1 However this gives me (192.168.1.71) and I must remove the ( ) from ...
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Is there a file for ip neigh show

I am looking for the file containing the output of ip neigh show command. I need the file as I can't invoke command and redirect as per requirement. The closest thing I found is the file /proc/net/arp....
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4 votes
1 answer
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Best way to filter/limit ARP packets on embedded Linux

I have an embedded Linux on some network device. Because this device is pretty important I have to make many network tests (I have a separate device for that). These tests include flooding my device ...
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ARP requests sent from wrong interface on Hostapd managed access point

I am trying to setup a wireless access point, managed by Hostapd and with dynamic VLAN support. The VLANs are managed dynamically by a FreeRadius server that I use for 802.X authentication. I am ...
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2 votes
1 answer
438 views

Does `arp-scan` not work well in a wifi created by a hotspot?

When I use a wifi hotspot, sometimes I can't use sudo arp-scan -l to see other devices (except the hotspot), but sometimes I can see another laptop, but I never see another android phone. (The hotspot ...
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How can I find out the hostnames of other computers in the same local network?

In my local wifi, I can find out the IP and MAC of another computer which also runs Lubuntu, and whose hostname is known to me. $ sudo arp-scan olive [sudo] password for t: Interface: ...
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Ubuntu ARP reply configuration

I am wondering what/if there is any configuration that enables arp replies. I have an Ubuntu machine with two interfaces - one is ethernet to a non-public LAN, the other is Wifi which connects to the ...
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Why do I have these arp cache entries, for addresses way outside my network?

$ ip -4 neigh show dev eno1 209.132.181.16 FAILED 152.19.134.142 FAILED 85.236.55.6 FAILED 152.19.134.198 FAILED 8.43.85.67 FAILED 140.211.169.206 FAILED How could these weird ip neighbour (ARP)...
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ARP responses not arriving to virtual interface in Linux

I created virtual interface in Linux from command line, and asked for an IP address from the router with the following commands: ip link add link enp0s3 my-iface type macvlan ifconfig my-iface up ...
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Refresh arp entries in FreeBSD

In Linux, an ARP entry's age gets reset/refreshed if a packet comes by. However, it seems that FreeBSD simply sets a timer, and unconditionally evicts the ARP entry even if packets with that MAC-...
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2 votes
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How to inspect decrypted TLS/SSL traffic in Wireshark from program not supporting SSLKEYLOGFILE?

TL;DR: I feel I'm pretty close to doing so by using sslsplit's interface mirroring, but I ran into an issue where the kernel is not replying to ARP requests that sslsplit is sending out on the ...
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How can I track down the source of an Ethernet ARP table issue between Linux laptops?

On our home LAN, after rebooting the router, I cannot ssh from laptop A to laptop B except via the router. However, after doing a ping from laptop B to laptop A, I can connect normally from A to B. I ...
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2 votes
1 answer
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DHCP works on wifi but my computer cannot receive unicast packets only broadcast packets

I cannot use my wireless capabilities of my laptop at all. I connect to my home router manually (without using the network manager, I purged it). Using the following commands: ifconfig wlan0 up ...
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2 votes
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Ubuntu not replying to ARP requests

I experience a behavior on my linux machine that I cannot explain. I see incoming ARP requests but they are not answered by my machine. When I plug the Ethernet cable into a Windows 10 machine those ...
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NMAP network scan shows IP-addresses and MAC addresses of items that are then missing from a subsequent arp-cache dump?

The logic I have is this get the definition of the subnet use nmap to scan every item in the subnet to populate the arp cache use the /usr/sbin/arp tool to dump the arp cache parse the arp-cache to ...
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ARP hostnames problem

I am having problem with viewing hostnames of devices located in my LAN. On my first laptop (Ubuntu 18.04 LTS Desktop edition) result of following command: arp -a Is exactly what I want: X (192.168....
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OpenBSD not replying to ARP requests

I am setting up an OpenBSD system as a router, I have one interface as the upstream, then another with a vlan configured: Upstream(em0): inet 10.0.2.20 255.255.255.0 NONE description upstream ...
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1 vote
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Linux - net.ipv4.conf.all [duplicate]

I'm changing the default setting for arp_ignore on an ubuntu 16.04 server, from it's default value 0 to 1. My understanding of the /proc/sys/net/ipv4/conf/ directory is that files under all will ...
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