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Chapter 24. DHCP

The dhcpd daemon is used in Red Hat Enterprise Linux to dynamically deliver and configure Layer 3 TCP/IP details for clients.
The dhcp package provides the DHCP server and the dhcpd daemon. Enter the following command to see if the dhcp package is installed:
~]# rpm -q dhcp
package dhcp is not installed
If it is not installed, use the yum utility as root to install it:
~]# yum install dhcp

24.1. DHCP and SELinux

When dhcpd is enabled, it runs confined by default. Confined processes run in their own domains, and are separated from other confined processes. If a confined process is compromised by an attacker, depending on SELinux policy configuration, an attacker's access to resources and the possible damage they can do is limited. The following example demonstrates dhcpd and related processes running in their own domain. This example assumes the dhcp package is installed and that the dhcpd service has been started:
  1. Run the getenforce command to confirm SELinux is running in enforcing mode:
    ~]$ getenforce
    The command returns Enforcing when SELinux is running in enforcing mode.
  2. Enter the following command as the root user to start dhcpd:
    ~]# systemctl start dhcpd.service
    Confirm that the service is running. The output should include the information below (only the time stamp will differ):
    ~]# systemctl status dhcpd.service
    dhcpd.service - DHCPv4 Server Daemon
       Loaded: loaded (/usr/lib/systemd/system/dhcpd.service; disabled)
       Active: active (running) since Mon 2013-08-05 11:49:07 CEST; 3h 20min ago
  3. Run following command to view the dhcpd processes:
    ~]$ ps -eZ | grep dhcpd
    system_u:system_r:dhcpd_t:s0 5483 ?        00:00:00 dhcpd
    The SELinux context associated with the dhcpd process is system_u:system_r:dhcpd_t:s0.