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Description
It is suggested to use ISC-DHCP-SERVER free solution as a DHCP server. The solution allows performing the following tasks in relation to Eltex.SoftWLC project:
- Assigning primary (external) IP addresses to access points with option 43 (suboptions 11 and 12) that makes it possible to create GRE tunnels to ESR.
- Assigning secondary (management, tunnel) IP addresses to access points with option 43 (suboptions 10 and 13) for AP management, detection and automatic initialization.
- Assigning IP addresses to Wi-Fi users connecting to access points.
- DHCP clients classification using option 82, option 60 and giAddrField.
Starting/stopping procedure
To stop the service, the following command is used:
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* isc-dhcp-server is not running |
if it is not.
DHCP server configuration
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| The solutions provided are relevant to typical network organization schemes, but they may differ from the configuration required for your network! |
Network settings
Network Interfaces
DHCP server should have interfaces in three subnets:
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auto eth1.102 # Interface in outer operator's exchange network iface eth1.102 inet static address 192.168.114.8 netmask 255.255.255.192 network 192.168.114.0 vlan_raw_device eth1 auto eth1.100 # Interface in inner operator network iface eth1.100 inet static address 172.17.209.9 netmask 255.255.255.192 network 172.17.209.0 vlan_raw_device eth1 auto eth1.101 # Interface for assigning IP addresses to access points iface eth1.101 inet static address 10.203.5.7 netmask 255.255.255.192 network 10.203.5.0 vlan_raw_device eth1 |
Routing
DHCP server should have access to three subnets:
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up ip route add 100.65.64.0/22 via 192.168.114.10 up ip route add 192.168.200.0/22 via 192.168.114.10 up ip route add 10.203.32.0/19 via 10.203.5.1 |
ISC-DHCP-SERVER configuration
/etc/default/isc-dhcp-server
The file contains basic settings, in particular the list of network interfaces used:
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INTERFACES="eth1.101 eth1.102" |
/etc/dhcp/dhcpd.conf
DHCP server's address pool configuration.
Configuration example
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default-lease-time 60;
max-lease-time 120;
log-facility local7;
class "ELTEX-DEVICES" {
match if (
(substring (option vendor-class-identifier, 0, 14) = "ELTEX_WEP-12AC") or
(substring (option vendor-class-identifier, 0, 14) = "ELTEX_WOP-12AC") or
(substring (option vendor-class-identifier, 0, 14) = "ELTX_WEP-12AC") or
(substring (option vendor-class-identifier, 0, 14) = "ELTX_WOP-12AC")
);
}
subnet 192.168.114.64 netmask 255.255.255.192 {}
subnet 10.203.5.64 netmask 255.255.255.192 {}
#first IP-subnet for assigning primary addresses to access points
subnet 10.203.32.0 netmask 255.255.254.0 {
pool {
option routers 10.203.32.2;
range 10.203.32.130 10.203.32.230;
failover peer "dhcp-failover";
option vendor-encapsulated-options 0B:0c:31:30:2E:32:30:33:2E:35:2E:31:31:32:0C:0C:31:30:2E:32:30:33:2E:35:2E:31:31:33;
allow members of "ELTEX-DEVICES";
}
}
#managed IP-subnet for assigning secondary addresses to access points
subnet 192.168.200.0 netmask 255.255.252.0 {
pool {
option routers 192.168.200.5;
range 192.168.200.120 192.168.200.164;
failover peer "dhcp-failover";
option vendor-encapsulated-options A:F:31:39:32:2E:31:36:38:2E:31:31:34:2E:31:30:34;
allow members of "ELTEX-DEVICES";
}
}
#User IP-subnet for users (clients)
subnet 200.65.64.0 netmask 255.255.240.0 {
pool {
option routers 200.65.64.5;
range 200.65.64.200 200.65.64.250;
failover peer "dhcp-failover";
option domain-name-servers 172.16.0.1, 8.8.8.8;
}
} |
Configuring access points' static addresses
If predetermined IP addresses of access points (secondary addresses) should be used in management network, a list of static hosts can be configured. Take the following steps in order to avoid /etc/dhcp/dhcpd.conf overload:
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The lists should be created on both servers and kept updated. Restart servers after changing the lists' contents.
Option 82 usage
If option 82 is required, new classes should be created as follows:
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After that, addresses from the pool will be assigned only to devices of this class.
Option 43 usage
The option is used to transfer vendor-specific data to DHCP clients.
The following suboptions are used in SoftWLC:
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If several suboptions should be transferred in a pool, they should be written in the same line. E.g. for suboptions 10 and 13, it will look like this:
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dhcpd configuration file check
To check a configuration file for syntax errors without restarting DHCP server and applying a configuration, use dhcpd utility.
To run a check, launch dhcpd utility with -t modifier. If the configuration file is not located in the default directory, add -cf modifier
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root@vagrant-ubuntu-trusty-64-test1111:~# dhcpd -t -cf /etc/dhcp/dhcpd_test.conf Internet Systems Consortium DHCP Server 4.2.4 Copyright 2004-2012 Internet Systems Consortium. All rights reserved. For info, please visit https://www.isc.org/software/dhcp/ /etc/dhcp/dhcpd_test.conf line 97: semicolon expected. range ^ /etc/dhcp/dhcpd_test.conf line 105: Pool declaration with no address range. } ^ Pool declarations must always contain at least one range statement. Configuration file errors encountered – exiting |
DHCP-failover configuration
Add a definition to /etc/dhcp/dhcpd.conf configuration file
On the first server:
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| Server time synchronization is essential for DHCP-failover operation. If desynchronization occurs, failures are possible. |
OMAPI configuration
To set monitoring and DHCP servers' status check, generate a key and specify it in DHCP server configuration file. At first, generate keys by adding -K modifier and by specifying destination directory
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