DHCP Server Configuration

DHCP Server Configuration

Step-1:  To check dhcp  rpm package is installed or not by following this command:
                     
(if installed then it will show dhcp packages)

[root@dhcp ~]# rpm -qa | grep –i dhcp*    or
[root@dhcp ~]#  rpm –qa dhcp*

dhcp-3.0.5-21.el5
dhcp-devel-3.0.5-21.el5
libdhcp-devel-1.20-10.el5
dhcpv6-client-1.0.10-17.el5
libdhcp-1.20-10.el5
libdhcp4client-3.0.5-21.el5
libdhcp6client-devel-1.0.10-17.el5
libdhcp4client-devel-3.0.5-21.el5
dhclient-3.0.5-21.el5

If not installed, then installed the packages using  Yum command:

[root@dhcp ~]# Yum Install dhcp* lib*

Step-2: Check and Configure the Network Card:

[root@dhcp ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0

(Original File):

#Broadcom Corporation Net link BCM57875 Gigabyte Ethernet PCI Express
DEVICE=eth0
BOOTPROTO=dhcp
HWADDR=00:0C:29: EB: B2: CA
ONBOOT=yes

(Modified File):

#Broadcom Corporation Net link BCM57875 Gigabyte Ethernet PCI Express
DEVICE=eth0
BOOTPROTO=static
HWADDR=00:0C:29: EB: B2: CA
ONBOOT=yes
TYPE=Ethernet
PEERDNS=no
USERCTL=no
IPV6INIT=no
IPADDR=210.207.201.4
NETMASK=255.255.255.0
NETWORK=210.207.201.0
BROADCAST=210.207.201.255

Press Esc → Shift + : → x! → Enter (For Save and Exit the Vi Editor).

After changing you have to reload/restart the NIC(eth0) card by following command:

[root@dhcp ~]# ifdown eth0
[root@dhcp ~]# ifup eth0
[root@dhcp ~]# service network restart

Step-3:  After complete the NIC configure you have to change the host name by following this                             command:

[root@dhcp ~]# vi /etc/sysconfig/network

(Original File):

NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=localhost.localdomain

(Modified File):

NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=dhcp
Press Esc → Shift + : → x! → Enter

Step-3:  Edit the resolv.conf file by following this command

[root@dhcp ~]# vi /etc/resolv.conf

search alphabd.net
nameserver 210.207.201.1
nameserver 210.207.201.2

Step-4:  Copy & Rename the DHCP configuration file & Change the permission by following this                                command:

[root@dhcp ~]# cd /usr/share/doc/dhcp-3.0.5/
[root@dhcp dhcp-3.0.5]# cp dhcpd.conf.sample  /etc/dhcpd.conf
[root@dhcp dhcp-3.0.5]# chmod 777 /etc/dhcpd.conf

Now Edit this file using vi editor & make some change in to this file.

[root@dhcp ~]# vi /etc/dhcpd.conf

(Original File):

ddns-update-style interim;
ignore client-updates;

subnet 192.168.0.0 netmask 255.255.255.0 {

# --- default gateway
      option routers                192.168.0.1;
      option subnet-mask            255.255.255.0;

      option nis-domain       "domain.org";
      option domain-name            "domain.org";
      option domain-name-servers    192.168.1.1;

      option time-offset            -18000;     # Eastern Standard Time
#     option ntp-servers            192.168.1.1;
#     option netbios-name-servers   192.168.1.1;
# --- Selects point-to-point node (default is hybrid). Don't change this unless
# -- you understand Netbios very well
#     option netbios-node-type 2;

      range dynamic-bootp 192.168.0.128 192.168.0.254;
      default-lease-time 21600;
      max-lease-time 43200;

      # we want the nameserver to appear at a fixed address
      host ns {
            next-server marvin.redhat.com;
            hardware ethernet 12:34:56:78:AB:CD;
            fixed-address 207.175.42.254;
      }
}
(Modified File):

ddns-update-style interim;
ignore client-updates;

subnet 210.207.201.0 netmask 255.255.255.0 {

# --- default gateway
      option routers                210.207.201.4;      
      option subnet-mask            255.255.255.0;

#     option nis-domain       "domain.org";
      option domain-name            "alphabd.net";      
      option domain-name-servers    210.207.201.1;

      option time-offset            -18000;     # Eastern Standard Time
#     option ntp-servers            192.168.1.1;
#     option netbios-name-servers   192.168.1.1;
# --- Selects point-to-point node (default is hybrid). Don't change this unless
# -- you understand Netbios very well
#     option netbios-node-type 2;

      range dynamic-bootp 210.207.201.50 210.207.201.254;
      default-lease-time 43200;
      max-lease-time 86400;

      # we want the nameserver to appear at a fixed address
      host ns {
            next-server marvin.redhat.com;
            hardware ethernet 12:34:56:78:AB:CD;
            fixed-address 207.175.42.254;
      }

      host pc01 {
            hardware ethernet 00:1E:68:91:BB:EC;
            fixed-address 210.207.201.100;
      }

      host client01 {
            hardware ethernet 00:0C:29:8C:95:01;
            fixed-address 210.207.201.150;
      }

}
Esc → Shift + : → x! → Enter

Step-5:  Create a dhcp.leases file that the DHCP server grants to the DHCP client to use a particular IP   address. If it does not exist dhcp server will fail to provide IP address for dhcp cient.

[root@dhcp ~]# touch /var/lib/dhcpd/dhcpd.leases
[root@dhcp ~]# service network restart
[root@dhcp ~]# service dhcpd restart

Step-6:   Client Configuration for using DHCP.

Linux Client

[root@dhcp ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0

#Broadcom Corporation Net link BCM57875 Gigabyte Ethernet PCI Express
DEVICE=eth0
BOOTPROTO=dhcp
HWADDR=00:0C:29: EB: B2: CA
ONBOOT=yes
TYPE=Ethernet

Windows Client

From NIC Properties =>> set Obtain an IP Address Automatically

Step-7:   Renewing IP Address

Renew an IP Address in Linux

The -r flag explicitly releases the current lease, and once the lease has been released, the client exits. For example, open terminal and type the command:

[root@dhcp ~]# dhclient –r

Now obtain fresh IP:

[root@client1 ~]# dhclient

Or you can put the two commands on a single line:

[rnbsp; oot@client1 ~]# dhclient -r; dhclient

There is no need to restart network service. Above command should work with any Linux distro such as RHEL, Fedora, and others. On a related note you can also try out the following commands:

[root@client1 ~]# ifdown eth0
[root@client1 ~]# ifup eth0
[root@client1 ~]# /etc/init.d/network restart

Renew an IP Address in Windows

Open Command Prompt → Then Type The following command

C:\Documents and Settings\Administrator> Ipconfig  /release
C:\Documents and Settings\Administrator> Ipconfig  /renew
C:\Documents and Settings\Administrator> Ipconfig  /all





http://yourlinuxzone.blogspot.in/2011/12/configure-dhcp-server-on-red-hat.html

Display Apache Server Status with mod_status

Q. How do I display Apache server status such as current server activity and performance under Red Hat Enterprise Linux / UNIX / BSD?

A. You can use regular Linux / UNIX commands such as lsof, netstat, top, vmstat and others to view apache server activity, status and performance from a shell prompt. However, I recommend mod_status because it provides good information about Apache server.

mod_status Apache module

There is also mod_status built into Apache web server to get server status from a web browser. With this module you can easily find out how well your server is preforming. All reports are generated in a html format. You can easily find out following type of information:

1. Total number of worker serving requests
2. Total number of of idle worker
3. Find the status of each worker, the number of requests that worker has performed and the total number of bytes served by the worker
4. Total number byte count served
5. Other information such as CPU usage, number of requests per second,current hosts and requests being processed etc.

How do I configure mod_status to display Apache web server status?

Open your httpd.conf / apache2.conf file:
# vi httpd.conf
Fnd out (append line) that read as follows to allow access from 10.1.2.5 only:

SetHandler server-status
Order Deny,Allow
Deny from all
Allow from 10.1.2.5

You can also restrict access using a domain name:

SetHandler server-status
Order Deny,Allow
Deny from all
Allow from w1.g2.dc3.helpdesk.nixcraft.com

Save and close the file. Restart web server, enter:
# service httpd restart
Fire a webbrowser and type the url http://your-server-ip/server-status or http://your-corp.com/server-status

Sample Apache Server Status Report

Fix Apache - No space left on device: Couldn't create accept lock or Cannot create SSLMutex

When dealing with mem-leaks in my mod_perl-apps I ran into a curious apache-problem. After a while apache could not be started but failed with strange errors like: [emerg] (28)No space left on device: Couldn't create accept lock or [crit] (28)No space left on device: mod_rewrite: could not create rewrite_log_lock Configuration Failed or [Wed Dec 07 00:00:09 2005] [error] (28)No space left on device: Cannot create SSLMutex There was definitely enough space on the device where the locks are stored (default /usr/local/apache2/logs/). I tried to explicetely different Lockfiles using the LockFile-directive but this did not help. I also tried a non-default AcceptMutex (flock) which then solved the acceptlock-issue and ended in the rewrite_log_lock-issue. Only reboot of the system helped out of my crisis. Solution: There were myriads of semaphore-arrays left, owned by my apache-user.

ipcs -s | grep apache

Removing this semaphores immediately solved the problem.

ipcs -s | grep apacheipcs -s | grep apache | perl -e 'while () { @a=split(/\s+/); print `ipcrm sem $a[1]`}'


Then restart the Apache. No need to restart the server Just restart the server & enjoy the work.




very good website.

http://openhelp.net/