Tukang nggame tips:ARP Linux Command

tukang nggame tips~The Address Resolution Protocol (ARP) is the method for finding a host's link layer (hardware) address. ARP is primarily used to translate IP addresses to Ethernet MAC addresses. Media Access Control address (MAC address) is a unique identifier assigned to most network adapters. This is example Ethernet  HWaddr/Mac Address 00:1c:11:19:c1:11

With GNU/Linux we can use a command line to manipulate the system ARP cache. The command is arp. Arp manipulates or displays the kernel's IPv4 network neighbour cache. It can add entries to the table, delete one or display the current content. ARP stands for Address Resolution Protocol, which is used to find the media access control address  of  a  network neighbour for a given IPv4 Address.

Howto use it ?
From manual page Linux we get a synopsis to use it :

SYNOPSIS
       arp [-vn] [-H type] [-i if] [-a] [hostname]

       arp [-v] [-i if] -d hostname [pub]

       arp [-v] [-H type] [-i if] -s hostname hw_addr [temp]

       arp [-v] [-H type] [-i if] -s hostname hw_addr [netmask nm] pub

       arp [-v] [-H type] [-i if] -Ds hostname ifname [netmask nm] pub

       arp [-vnD] [-H type] [-i if] -f [filename]

With that command we can define the client mac address with fix ip address and acquaint it to router.

CLIENT/COMPUTER 1,2..n (c1,c2,..cn) -------------ROUTER

c1 mac address 00:1c:11:19:c1:11 IP address  192.168.1.1
c1 mac address 00:1c:11:19:b1:12 IP address  192.168.1.2

with that arp Linux command

#/usr/sbin/arp -s 192.168.1.1     00:1c:11:19:c1:11
#/usr/sbin/arp -s 192.168.1.1     00:1c:11:19:b1:12

or we create a bash file, example arp.sh. That content

#!/bin/bash
#tukang nggame computer
/usr/sbin/arp -s 192.168.1.1     00:1c:11:19:c1:11
#John computer
/usr/sbin/arp -s 192.168.1.1     00:1c:11:19:b1:12

Then, change permision for execution.

#chmod  755 arp.sh

The running that file

#./arp.sh

What advantage that methode ?
Now, router have database mac address and IP Address every computer. So a network administrator manage the router more easy. Because client can't change their Mac address offhand, if they was changed mac address or IP address that same with router database, so their computer can connect to router. It useful if you combine apply with squid/proxy server.

tukang nggame Ref:

http://en.wikipedia.org/wiki/MAC_address

http://en.wikipedia.org/wiki/Address_Resolution_Protocol

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