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Showing posts with label dhcp. Show all posts
Showing posts with label dhcp. Show all posts

How to Configure Wireless Network Step by Step

By  6:10 PM  , , ,  
We have covered all CCNA exam topics in our wireless networking section. As its new topic in CCNA exam so you have very little chance to get simulated base question on wireless networking. Still we recommended you to get familiar with some basic wireless configuration.

Step by Step guides For wireless configuration

Download this topology and load it in packet tracer
Download File
wireless network
In this topology we have three pc connected with Linksys Wireless routers.
  • DHCP is configured and enabled on Wireless router
  • IP pool for DHCP is 192.168.0.100 to 192.168.0.150
  • PC are configured to receive IP from DHCP Server
  • No security is configured
  • Default SSID is configured to Default
  • Topology is working on infrastructure mode
  • Default user name and password is admin
  • IP of wireless is set to 192.168.0.1
Now your task is to:-
  • Configure Static IP on PC and Wireless Router
  • Change SSID to MotherNetwork
  • Change IP address of router to 10.0.0.1 and 10.0.0.2 of PC0 10.0.0.3 of PC1 10.0.0.4 of PC2
  • Secure your network by configuring WAP key on Router
  • Connect PC by using WAP key
To complete these tasks follow this step by step guide of how to configure wireless network
As given in question our network is running on 192.168.0.0 network and all PC's are DHCP clients and functioning properly. So we will first connect to Wireless router to off DHCP.
Double click on PC and select Web Browser. As given in question IP of Wireless router is 192.168.0.1 so give it in Web browser and press enter, now it will ask for authentication which is also given in question. Give user name admin and Password to admin
How to Configure Wireless Network Step by Step
This will bring GUI mode of Wireless router. Scroll down screen to Network Step and Select Disable DHCP

How to Configure Wireless Network Step by Step
Go in end of page and click on Save setting this will save setting click on continue for further setting
configure wireless device
Now select Administration from top Manu and change password to test and go in the end of page and Click on Save Setting
wireless device set password
Click on continue for further setting. This time it will ask you to authenticate again give new password test this time
wireless set password
Now click on wireless tab and set default SSID to MotherNetwork
wireless ssid
Now Select wireless security and change Security Mode to WEP
configure wireless security
Set Key1 to 0123456789

Again go in the end of page and Click on Save Setting
Now we have completed all given task on Wireless router. Now configure the static IP on all three PC's
Double click on pc select Desktop tab click on IP configuration select Static IP and set IP as given below
PCIPSubnet MaskDefault Gateway
PC0192.168.0.2255.255.255.0192.168.0.1
PC1192.168.0.3255.255.255.0192.168.0.1
PC2192.168.0.4255.255.255.0192.168.0.1
Now it's time to connect PC's from Wireless router. To do so click PC select Desktop click on PC Wireless
wireless devices
Click on connect tab and click on Refresh button
wireless connect
As you can see in image that Wireless device is accessing MotherNetwork on CH 6 and signal strength is 100%. In left side you can see that WEP security is configured in network. Click on connect button to connect MotherNetwork
It will ask for WAP key insert 0123456789 and click connect
wireless key
It will connect you with wireless router.
As you can see in image below that system is connected. And PCI card is active.
wireless pc connected
Repeat same process on PC1 and PC2.
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linux dhcp configuration

By  10:54 PM  , , ,  
 
(DHCP) Dynamic Host Configuration Protocol  automatically assigns IP addresses and other network configuration information (subnetmask, broadcast address, etc) to computers on a network. A client configured for DHCP will send out a broadcast request to the DHCP server requesting an address. The DHCP server will then issue a "lease" and assign it to that client. The time period of a valid lease can be specified on the server. DHCP reduces the amount of time required to configure clients and allows one to move a computer to various networks and be configured with the appropriate IP address, gateway and subnet mask. For ISP's it conserves the limited number of IP addresses it may use. DHCP servers may assign a "static" IP address to specified hardware. Microsoft NetBios information is often included in the network information sent by the DHCP server. 
 
DHCP assignment:

  1. Lease Request: Client broadcasts request to DHCP server with a source address of 0.0.0.0 and a destination address of 255.255.255.255. The request includes the MAC address which is used to direct the reply. 
  2.  
  3. IP lease offer: DHCP server replies with an IP address, subnet mask, network gateway, name of the domain, name servers, duration of the lease and the IP address of the DHCP server.
  4. Lease Selection: Client recieves offer and broadcasts to al DHCP servers that will accept given offer so that other DHCP server need not make an offer.
  5. The DHCP server then sends an ack to the client. The client is configured to use TCP/IP.
  6. Lease Renewal: When half of the lease time has expired, the client will issue a new request to the DHCP server.

DHCP server installation:
  • Red Hat/CentOS/Fedora: rpm -ivh dhcp-x.xxx.elx.i386.rpm
  • Ubuntu/Debian 8: apt-get install dhcp3-server
    ( Later releases of Ubuntu (11.04) used the busybox release known as udhcpd and the configuration is NOT shown here)

Starting DHCP server:
  • Red Hat/CentOS/Fedora: service dhcpd start
    (or /etc/rc.d/init.d/dhcpd start for Red Hat, Fedora and CentOS Linux distributions)
  • Ubuntu/Debian: /etc/init.d/networking restart

Sample DHCP server config file: (DHCP v3.0.1)
  • Red Hat/CentOS/Fedora: /etc/dhcpd.conf
    (See /usr/share/doc/dhcp-3.X/dhcp.conf.sample)
    [Potential Pitfall]: Its /etc/dhcpd.conf NOT /etc/dhcp.conf !!
  • Ubuntu/Debian: /etc/default/dhcp3-server
01ddns-update-style interim;                                   # Required for dhcp 3.0+ / Red Hat 8.0+
02ignore client-updates;
03 
04subnet 192.168.1.0 netmask 255.255.255.0 {
05 
06        range 192.168.1.128 192.168.1.254;                   # Range of IP addresses to be issued to DHCP clients
07           option subnet-mask              255.255.255.0;    # Default subnet mask to be used by DHCP clients
08           option broadcast-address        192.168.1.255;    # Default broadcastaddress to be used by DHCP clients
09           option routers                  192.168.1.1;      # Default gateway to be used by DHCP clients
10           option domain-name              "your-domain.org";
11           option domain-name-servers      40.175.42.254, 40.175.42.253;           # Default DNS to be used by DHCP clients
12           option netbios-name-servers     192.168.1.100;    # Specify a WINS server for MS/Windows clients.
13                                                             # (Optional. Specify if used on your network)
14 
15#         DHCP requests are not forwarded. Applies when there is more than one ethernet device and forwarding is configured.
16#       option ipforwarding off;
17 
18        default-lease-time 21600;                            # Amount of time in seconds that a client may keep the IP address
19        max-lease-time 43200;
20 
21        option time-offset              -18000;              # Eastern Standard Time
22#       option ntp-servers              192.168.1.1;         # Default NTP server to be used by DHCP clients
23#       option netbios-name-servers     192.168.1.1;
24# --- Selects point-to-point node (default is hybrid). Don't change this unless you understand Netbios very well
25#       option netbios-node-type 2;
26 
27        # We want the nameserver "ns2" to appear at a fixed address.
28        # Name server with this specified MAC address will recieve this IP.
29 
30        host ns2 {
31                next-server ns2.your-domain.com;
32                hardware ethernet 00:02:c3:d0:e5:83;
33                fixed-address 40.175.42.254;
34        }
35 
36        # Laser printer obtains IP address via DHCP. This assures that the
37        # printer with this MAC address will get this IP address every time.
38 
39        host laser-printer-lex1 {
40                hardware ethernet 08:00:2b:4c:a3:82;
41                fixed-address 192.168.1.120;
42        }
43}
Test configuration file for errors with the following command: /etc/rc.d/init.d/dhcpd configtest
(Other distributions may use: /usr/sbin/dhcpd -f)
Note: The MAC addresses for the static address name server (ns2.your-domain.com),
can be obtained with the command /sbin/ifconfig: 
eth0      Link encap:Ethernet  HWaddr 00:02:C3:D0:E5:83
          inet addr:40.175.42.254  Bcast:40.175.42.255  Mask:255.255.255.0
          inet6 addr: fe80::202:b3ff:fef0:e484/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:4070 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3878 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:3406445 (3.2 MiB)  TX bytes:439612 (429.3 KiB)
When dhcpd is running it will generate entries in the file: /var/lib/dhcp/dhcpd.leases 
lease 192.168.1.128 {
 starts 2 2004/12/01 20:07:05;
 ends 3 2004/12/02 08:07:05;
 hardware ethernet 00:00:e8:4a:2c:5c;
 uid 01:00:00:e8:4c:5d:31;
 client-hostname "Node1";
}

Options:
  • ddns-update-style:
    • interim: allows your DHCP server to update a DNS server whenever it hands out a lease. Allows your DNS server to know which IP addresses are associated with which computers in your network. Requires that your DNS server support DDNS (Dynamic DNS).
    • none: to disable dynamic DNS updates or DNS is not supporting DDNS.
    • ad-hoc: been deprecated and shouldn't be used
  • Default options (Red Hat/CentOS/Fedora) are set in /etc/sysconfig/dhcpd
LANs separated by routers: In order to have your DHCP broadcast pass through a router on the the next network, one must configure the router to allow DHCP relay. (Cisco: ip-helper address, Juniper: dhcp-relay) The local lan subnet{ } configuration must come before the configuration directives of the remote LANs.
Look for errors in /var/log/messages
See dhcp-options man page below.

DHCP man pages:

DHCP RFC's: RFC2131, RFC1541 (obsolete), RFC2132
Note: DHCP client will overwrite your /etc/resolv.conf file with new information recieved from the DHCP server.

Red more :
Configuring Your Laptop to Use DHCP
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