You can also set up your DHCP server in the web GUI, which includes many  more options than the console does.

1. Navigate to Services | DHCP Server. There will be a separate tab for each non-WAN interface.
2. Click on the tab for the interface you want to configure. The following screenshot shows the configuration page for the LAN interface:

3. In the General Options section, there is an Enable checkbox, which, as you probably guessed, enables the DHCP server on the interface.
4. There are also Range edit boxes where you can define the range of assigned addresses. If this is all you wanted to do (which is no more than the level of DHCP configuration the console provides), you can click on the Save button at the bottom of the page and the DHCP server will now be up and running.

One of the options added in version 2.4, the BOOTP checkbox, if checked, will cause the DHCP server to ignore BOOTP queries. BOOTP is a protocol by which networks can assign IP addresses to users. Like DHCP, it uses port 67 and port 68 to communicate. It also predates DHCP (it was originally defined in RFC 951 in September 1985, while DHCP was not defined until March 1997). Both BOOTP and DHCP are methods of automatic IP assignment. However, BOOTP differs from DHCP in several significant ways:

• BOOTP uses the User Datagram Protocol (UDP), while DHCP uses the Transport Control Protocol (TCP)
• BOOTP only works with IPv4 networks, while DHCP has been revised to support IPv6 networks
• BOOTP does not support DHCP, but the reverse is true: parts of BOOTP provides services to DHCP, and DHCP servers provide legacy BOOTP functionality

Therefore, a DHCP server will normally also act as a BOOTP server. This can be problematic, however, because BOOTP leases do not have a maximum lease time by default (the original definition of BOOTP does not even include the lease concept). Therefore, BOOTP leases can easily exhaust the DHCP address pool. One possible solution is to just ignore BOOTP queries, which may seem like overkill, but it also eliminates the possibility of DHCP support for BOOTP ever being a problem. If you ever have problems with BOOTP queries, you can enable this option.

1. The Ignore denied clients checkbox, if checked, will cause pfSense to ignore denied clients rather than reject them. This, however, is not compatible with failover, because another pfSense system in the failover group will assume that the failure to respond to a DHCP request indicates a failure of the other system.
2. The Additional Pools section allows you to specify additional pools of addresses outside of the range specified in General Options.
3. You add address pools by clicking on the Add pool button and entering the new range.
4. Once a new pool has been added, it will appear under the Additional Pools section, and you will be able to edit or delete the pool from the DHCP Server page.

5. You may want to set up your system so that only devices with certain MAC addresses receive DHCP leases. If so, check the Deny unknown clients checkbox.
6. You will then have to scroll down to the Other Options section and click on the Advanced button next to the MAC Address Control section.
7. In the MAC Allow edit box, specify the MAC addresses of the devices (as comma-separated values with no spaces) to which you want to allow access. If you want to deny access to certain devices, you can specify their MAC addresses in the MAC Deny edit box.

There may be devices on your network (for example, file servers and printers) which need to have the same IP address at all times. For these devices, you can rely on static mappings.

8. If you scroll down to the bottom of the page, you will find a section labeled DHCP Static Mappings for this Interface. Following this heading and to the right, there will be an Add button which will launch a page on which you can add a mapping.
9. The first setting on this page is MAC Address. Here, you must enter the MAC address of the device which is to receive a static mapping.
10. To the right of the MAC Address edit box, there is a Copy My MAC button that will copy the MAC address of the device currently being used to connect to pfSense; this is provided for your convenience.
11. The MAC address is the only field you must enter. If this is all you enter, this MAC address will be added to the list of allowed MAC addresses for the DHCP server. To obtain a static mapping for this device, you need to enter an IP address in the IP Address field.

12. There is also a Hostname field, in which you can specify the hostname, minus the domain. This field is optional, but, if specified, will be forwarded to the DNS server to help identify the client.
13. Another optional field is Description, which just allows you to enter a text description of the static mapping.
14. The Client Identifier field allows you to enter a client identifier string which will then be sent to the DHCP server. If the client identifier is specified, this identifier, along with the assigned network address, will be used by the DHCP server to identify the client, per RFC 2131. The Client Identifier field allows you to enter a client identifier string which, when specified, is used along with the assigned network address by the DHCP server to identify the client, per RFCs 2131 and 6842.
15. In the Servers section, you can specify both WINS servers and DNS servers. WINS servers provide Windows with a means of mapping NetBIOS names to network addresses. If you don't have a WINS server on your network, you can leave this blank.
    • The DNS Servers fields need not be filled in most cases. If these fields are left blank and the DNS forwarder is enabled, pfSense will automatically assign itself as the DNS server for client PCs.
    • If the DNS forwarder is disabled and these fields are left blank, the default DNS servers specified in System | General Setup will be used. There are, however, circumstances in which you may want to override either the default DNS servers or the DNS forwarder:
      • When you need to specify custom DNS servers (for example, an Active Directory configuration in which Active Directory has its own DNS servers)
      • If you are using the Common Address Redundancy Protocol (CARP) in conjunction with the DNS forwarder, you should specify the CARP IP here.
16. If you want to register the client with a DDNS server, you can enter this information by scrolling down to Dynamic DNS and clicking on the Advanced button.
17. The Enable registration of DHCP client names in DNS checkbox enables DNS registration. If you want to enable DDNS registration, you must fill in the DDNS Domain field. There are also fields for the primary domain name server IP address, as well as the DDNS key name and key secret.