8821cu-20210916/docs/linux_dhcp_server_notes.txt

//Install dhcp server
[root@localhost ~]#yum install dhcp

//We shoule copy  /usr/share/doc/dhcp-4.2.0/dhcpd.conf.sample to /etc/dhcp/dhcpd.conf
//and modifiy /etc/dhcp/dhcpd.conf as the following
[root@localhost ~]#cat /etc/dhcp/dhcpd.conf
# dhcpd.conf
#
# Sample configuration file for ISC dhcpd
#

# option definitions common to all supported networks...
option domain-name "example.org";
option domain-name-servers ns1.example.org, ns2.example.org;

default-lease-time 600;
max-lease-time 7200;

# Use this to enble / disable dynamic dns updates globally.
#ddns-update-style none;

# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;

# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
log-facility local7;

# No service will be given on this subnet, but declaring it helps the
# DHCP server to understand the network topology.

subnet 10.152.187.0 netmask 255.255.255.0 {
}

# This is a very basic subnet declaration.

subnet 10.254.239.0 netmask 255.255.255.224 {
  range 10.254.239.10 10.254.239.20;
  option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
}

# This declaration allows BOOTP clients to get dynamic addresses,
# which we don't really recommend.

subnet 10.254.239.32 netmask 255.255.255.224 {
  range dynamic-bootp 10.254.239.40 10.254.239.60;
  option broadcast-address 10.254.239.31;
  option routers rtr-239-32-1.example.org;
}

# A slightly different configuration for an internal subnet.
subnet 192.168.1.0 netmask 255.255.255.0 {
  range 192.168.1.30 192.168.1.150;
  option domain-name-servers 192.168.1.254;
  option domain-name "internal.org";
  option routers 192.168.1.254;
  option broadcast-address 192.168.1.255;
  default-lease-time 6000;
  max-lease-time 7200;
}

subnet 172.21.69.0 netmask 255.255.255.0 {

}

# Hosts which require special configuration options can be listed in
# host statements.   If no address is specified, the address will be
# allocated dynamically (if possible), but the host-specific information
# will still come from the host declaration.

host passacaglia {
  hardware ethernet 0:0:c0:5d:bd:95;
  filename "vmunix.passacaglia";
  server-name "toccata.fugue.com";
}

# Fixed IP addresses can also be specified for hosts.   These addresses
# should not also be listed as being available for dynamic assignment.
# Hosts for which fixed IP addresses have been specified can boot using
# BOOTP or DHCP.   Hosts for which no fixed address is specified can only
# be booted with DHCP, unless there is an address range on the subnet
# to which a BOOTP client is connected which has the dynamic-bootp flag
# set.
host fantasia {
  hardware ethernet 08:00:07:26:c0:a5;
  fixed-address fantasia.fugue.com;
}

# You can declare a class of clients and then do address allocation
# based on that.   The example below shows a case where all clients
# in a certain class get addresses on the 10.17.224/24 subnet, and all
# other clients get addresses on the 10.0.29/24 subnet.

class "foo" {
  match if substring (option vendor-class-identifier, 0, 4) = "SUNW";
}

shared-network 224-29 {
  subnet 10.17.224.0 netmask 255.255.255.0 {
    option routers rtr-224.example.org;
  }
  subnet 10.0.29.0 netmask 255.255.255.0 {
    option routers rtr-29.example.org;
  }
  pool {
    allow members of "foo";
    range 10.17.224.10 10.17.224.250;
  }
  pool {
    deny members of "foo";
    range 10.0.29.10 10.0.29.230;
  }
}
[root@localhost ~]#

//Depends on the above setting, wlan interface IP would be 192.168.1.254
[root@localhost ~]#ifconfig wlan14 192.168.1.254

//Set only one interface as dhcp server
[root@localhost ~]#cat /etc/sysconfig/dhcpd
# Command line options here
DHCPDARGS=wlan0

//If /var/lib/dhcpd/dhcpd.leases doesn't exist,
//we should establish it
//This file is used to record clients information.
[root@localhost ~]#touch /var/lib/dhcpd/dhcpd.leases

//Execute
[root@localhost ~]#/etc/rc.d/init.d/dhcpd start