How to fix MAC Address with IP Address on DHCP server.
Today, I would like to monitor my internet network bandwidth. When my internet network is slow I often have questions from my boss “Why my internet network is slow, who are using a lot of internet bandwidth?”. I cannot answer these questions because I don’t have informations of current network status.
First step, I think I should know which IP Address is using a lot of internet bandwidth and second step I should know who is owner that IP Address.
The answer of the first step , I will use ntop software to answer this question. For the second step, I will fix all MAC Address of Laptop’s wireless card with IP Address on a DHCP Server. And this is my solutions :
1. Get a MAC Address from Client’s laptop such as A1:B2:C3:A1:B2:C3
2. Add the MAC Address into the file /etc/dhcpd.conf such as
ddns-update-style interim
ignore client-updates
subnet 192.168.1.0 netmask 255.255.255.0 {
# The range of IP addresses the server
# will issue to DHCP enabled PC clients
# booting up on the network
range 192.168.1.201 192.168.1.220;
# Set the amount of time in seconds that
# a client may keep the IP address
default-lease-time 86400;
max-lease-time 86400;
# Set the default gateway to be used by
# the PC clients
option routers 192.168.1.1;
# Don't forward DHCP requests from this
# NIC interface to any other NIC
# interfaces
option ip-forwarding off;
# Set the broadcast address and subnet mask
# to be used by the DHCP clients
option broadcast-address 192.168.1.255;
option subnet-mask 255.255.255.0;
# Set the NTP server to be used by the
# DHCP clients
option ntp-servers 192.168.1.100;
# Set the DNS server to be used by the
# DHCP clients
option domain-name-servers 192.168.1.100;
# If you specify a WINS server for your Windows clients,
# you need to include the following option in the dhcpd.conf file:
option netbios-name-servers 192.168.1.100;
# You can also assign specific IP addresses based on the clients'
# ethernet MAC address as follows (Host's name is "laser-printer":
host user-one {
hardware ethernet A1:B2:C3:A1:B2:C3;
fixed-address 192.168.1.222;
}
}
#
# List an unused interface here
#
subnet 192.168.2.0 netmask 255.255.255.0 {
}3. Check your configuration file is correct :
# /usr/sbin/dhcpd -t -cf /etc/dhcpd.conf
4. Restart your DHCP Service :
# service dhcpd restart
5. Set DHCP relay in your CISCO switch points to your DHCP Server (Assume your IP Address of DHCP Server is 192.168.1.201)
$ conf t $ conf t > interface vlan 10 $ conf t > ip address 192.168.1.1 255.255.255.0 $ conf t > no ip directed-broadcast $ conf t > ip helper-address 192.168.1.201 $ conf t > end
6. You can check all IP Addresses which receive from DHCP Server in file /var/lib/dhcp/dhcpd.leases
References :
1. http://www.redhatmagazine.com/2008/08/05/linux-dhcp-server-static-ips-are-gone-in-60-seconds/
2. http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch08_:_Configuring_the_DHCP_Server
3. http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a00800f0804.shtml
แล้วผลลัพธ์เป็นยังไงบ้างอ่ะครับ
In the first time, all client’s laptop could not receive a IP Address because I didn’t set DHCP delay on my Switch.
After I configured, all client’s laptop could receive a fix IP Address.
hello P’aoddy
It is a good idea for set subnet but it can give faster than your old net [before you are sitting the router] ??
i will msn with you
see you ^^