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Dynamic Host Control Protocol (Dynamic Host Control Protocol) (DHCP) to the network administrator provides a convenient way to provide network-layer address the changing dynamic network host or network. One of the most common DHCP service tool is ISC DHCP Server. Purpose is to give the host DHCP services provide the necessary network information to be able to communicate with each other and connected to other hosts in the network. DHCP service provides information on: DNS server information, network addresses (IP), subnet mask, default gateway information, host names, and so on.
This tutorial shows you how to run the 4.2.4 version in Debian 7.7 ISC-DHCP-Server to manage multiple virtual local area network (VLAN), it can also be easily applied to a single network.
The test network is to use the traditional way by Cisco routers to manage DHCP leases addresses. There are currently 12 VLAN through a centralized server to manage. The DHCP tasks transferred to a dedicated server, a router can recover the appropriate resources, the resources used on more important tasks, such as routing address, access control lists, flow monitoring, and network address translation.
Another DHCP service will be transferred to the benefits of a dedicated server, will be mentioned later, it can create a Dynamic Domain Name Server (DDNS), so that when the server requests a DHCP address from the host, so the host name of the new host will be added to the DNS inside the system.
Installing and Configuring ISC DHCP server
1, using the apt tool used to install Debian depot ISC software, to create the multi-homed server. Like the other tutorials require root or sudo access. Make appropriate changes to use the following command. (LCTT Annotation: The following comments are in brackets, remove the use of the time, # indicates root privileges to use)
# Apt-get install isc-dhcp-server [install the ISC DHCP Server software]
# Dpkg --get-selections isc-dhcp-server [confirm that the software has been successfully installed]
# Dpkg -s isc-dhcp-server [another way to confirm successful installation]
Install ISC DHCP Server in Debian
2, confirm service software has been installed, now we need to provide network information to configure the server so that it can be according to our need to distribute network information. As an administrator needs to know at least the DHCP information is as follows:
website address
Subnet Mask
Address range for dynamic allocation
Some other useful information server dynamic allocation comprises:
Default Gateway
DNS server IP address
domain name
CPU name
Network broadcast address
This option only allows ISC DHCP server processes a very small part of it. If you want to see all options and their description is required after you install the software, enter the following command:
#man dhcpd.conf
3, once the administrator has all the information necessary to determine the distribution of this server, it's time to configure the server and assign the necessary address pool. Before you configure any address pool or server configuration, you must configure the interface to a DHCP server listens on this server above.
On this particular server, set up after the NIC, DHCP listens name called 'bond0' interface. Please suitable according to your actual situation to change server and network environments. The following configuration are for this tutorial.
Configure ISC DHCP Network
This line specifies that DHCP traffic DHCP service listens on the interface (s) on. Modifying the master configuration file, assign the appropriate DHCP address pool on the network needs. The main configuration file /etc/dhcp/dhcpd.conf. Open this file with a text editor
# Nano / etc / dhcp / dhcpd.conf
This configuration file can be configured we need to address pool / host. Top of the file there is 'ddns-update-style' this sentence in this tutorial it is set to 'none'. In future tutorials will be talked about dynamic DNS, ISC-DHCP-Server will be integrated with BIND9, which enables the host name is updated to point to the IP address.
4, the next part of the global network administrators to configure settings such as DNS domain name, the default lease time, IP address, subnet mask, and others. If you want to know all the options, please read the man page of dhcpd.conf file, the command is as follows:
#man dhcpd.conf
For this server, we need at the top of the configuration file to configure some global network settings, so as not to be used to separate each address pool set up.
Configure ISC DDNS
We spent a little time to explain these options, although they are some of the global settings, but it can be individually configured for a particular address pool in this tutorial.
option domain-name "comptech.local"; - all using the host this DHCP server will be the DNS domain "comptech.local" of a option domain-name-servers 172.27.10.6; DHCP to configure all this DHCP server host distribution network DNS server address 172.27.10.6
option subnet-mask 255.255.255.0; - for each network device is assigned a subnet mask 255.255.255.0 or / 24
default-lease-time 3600; - the default valid address lease time (in seconds). If the lease time runs out, then the host can re-apply for a lease. If the lease is completed, then the corresponding address will also be recovered as soon as possible.
max-lease-time 86400; - it is the largest lease time can hire a host of (in seconds).
ping-check true; - This is an additional test to ensure that the network address of the network address of the server division issued is not currently another host in the network has been used.
ping-timeout; - before determining an address not previously used, the server will wait for ping response to the number of seconds.
ignore client-updates; now this option can be ignored, because DDNS has been disabled in the front in the configuration file, but when DDNS is running, this option ignores the request host update its DNS host name.
5, in the following line is the line of authority DHCP. Significance of this line is the server if the server is configured for file distribution network addresses, then the authority to cancel the keyword (authoritative stanza) comments.
By removing the key authoritative front of the '#', uncomment the global authority of the keyword. This server will be the only authority inside the network it manages.
Enable ISC Authoritative
By default, the server is assumed to be authoritative server is not on the network. The reason this is done for security reasons. I do not know if it was because of the configuration of the DHCP service, leading to improper configuration or to a network should not appear there, which will bring very serious connectivity issues. This line can also be used alone configuration on each network. This means that if the server is not the entire network DHCP server, authoritative line can be used in each individual network, rather than as in the screenshot above global configuration.
6, this step is to configure the server to manage all DHCP address pools / networks. For brevity, this tutorial is only mentioned one address pool configuration. As an administrator need to collect the necessary network information (such as domain names, network addresses, how many addresses can be distributed, etc.)
The following this address pool used by the administrator information is collected: Network ID 172.27.60.0, subnet mask 255.255.255.0 or / 24 subnet default gateway 172.27.60.1, broadcast address 172.27.60.255.0.
These information is important for building a new network in the dhcpd.conf file. Use a text editor to modify the configuration file to add a new network to go where we need to use the root or sudo access.
# Nano / etc / dhcp / dhcpd.conf
Configure DHCP Pools and Networks
This example is the current IP address assigned to the virtual server VMWare created. The first row shows the subnet mask of the network. All content is inside the brackets DHCP server option should be provided to the host on the network.
The first line, range 172.27.60.50 172.27.60.254; This line displays, DHCP service on the network can dynamically distribute to the host address range.
The second line, option routers 172.27.60.1; shown here is the default gateway address to all hosts inside the network distribution.
The last line, option broadcast-address 172.27.60.255; displaying the broadcast address of the current network. This address can not be included in the payment to sub-address range, because the broadcast address can not be assigned to a host on it.
It must be emphasized that the end of each line must be used (;) to end all networks must be created inside the {}.
7. If you want to create multiple networks, have created continue their respective options to save the text file. After configuration is complete if there are changes, ISC-DHCP-Server process needs to restart to make the new changes to take effect. Restart process can be accomplished via the following command:
# Service isc-dhcp-server restart
This command will restart the DHCP service, the administrator can use several different ways to check whether the server is ready to handle dhcp request. The easiest way is through the lsof command to see if the server is listening on port 67, the command is as follows:
# Lsof-i: 67
Check DHCP Listening Port
The results here show that the output dhcpd (DHCP service daemon) is running and listening on port 67. Since the mapping / etc / services file 67 port, the output port 67 is actually converted into "bootps".
In most systems it is very common, and now the server should be ready for a network connection, we can access a host network requests DHCP address verification service is normal.
Test client connections
8, many systems now use the network manager to maintain the network connection status, and therefore the device should be pre-configured, so long as the corresponding interface in the active state will be able to obtain DHCP.
However, when a device can not use the network manager, it may be necessary to manually obtain a DHCP address. The following steps will demonstrate how to get and how to manually check whether the server has already been distributed as desired address.
'Ifconfig' tool can be used to check the configuration of the interface. This station is used to test the DHCP server, it has only one network adapter (NIC), this card is named 'eth0'.
#ifconfig eth0
Check Network Interface IP Address
Check Network Interface IP Address
The output from the point of view, this device is currently no IPv4 address, this is very easy to test. We connect these devices to the DHCP server and issue a request. DHCP Client Tools on this device has been installed called 'dhclient' is. Because the operating system is different, so the client software is not the same as each other.
# Dhclient eth0
Request IP Address from DHCP
The current 'inet addr:' field shows the network address 172.27.60.0 fall within the scope of IPv4 addresses. The good news is that the current network is also configured with the correct subnet mask and broadcast address distributed.
Here looks pretty good, let's test to see if this device receives a new IP address is not sent by the server. Here we refer to the server's log files to complete this task. While the content of this log are hundreds of thousands, but only a few are used to determine which server is working properly. Here we use a tool 'tail', it only shows the last few lines of the log file, so we can not take a text editor to view all of the log files. Command is as follows:
# Tail / var / log / syslog
Check DHCP Logs
OK! Server records showed that it distributed an address to this host (HRTDEBXENSRV). Server as expected, to give it the authority to act as a network server for distributed network address. Thus DHCP server set up and running successfully. If necessary you can continue to configure other network troubleshooting, to ensure safety.
After the Debian tutorial I'll talk about some of the new ISC-DHCP-Server functionality. If you have time I will write an article on Bind9 and DDNS tutorial into the article inside. |
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