Synology NAS DHCP Server

Your Synology NAS can act as a DHCP server and assign dynamic IP addresses to DHCP clients within your local network.

To enable DHCP server:

  1. Go to Control Panel > DHCP Server > Network Interface.
  2. Select a network interface (e.g. LAN 1) to assign IP addresses to, and click Edit.
  3. On the pop-up window, click DHCP Server tab and select Enable DHCP server.
  4. Specify the following DHCP settings:
    • Address lease time (minutes)
    • Primary DNS
    • Secondary DNS (optinal)
    • Domain name (optional)
    • Enable Web Proxy Automatic Discovery (optional)
  5. Set up at least one subnet. For the subnet setup, click Add to specifiy the following information:
    • Start IP address
    • End IP address
    • Netmask
    • Gateway
  6. Click Create to show the created subnet in the list.
  7. After you create enough subnets, remember to enable at least one subnet.
  8. Click OK.

Note:

  • You can create as many subnets as you wish.
  • If coordinated with a DHCP relay server, your Synology NAS as the DHCP server can assign IP addresses to devices on another subnet.

 

DHCP Clients

You can find a list of DHCP clients and their network configurations (e.g. MAC address, IP address, hostname, the amount of time left before the DHCP lease expires, and the reservation status).

  1. Go to Control Panel > DHCP Server > Network Interface and select one desired interface.
  2. Click Edit > DHCP Clients to find the clients and the details.

To manage IP addresses for DHCP clients:

You can have a client always receive the same IP address during DHCP lease renewal and manage these clients.

  • To add DHCP clients: Click Add to assign the IP address to the client device.
  • To reserve the IP address: Click the lock icon to reserve the IP address for the current device.
  • To cancel the reservation: Click the lock icon to allow the current IP address to be used by another device after the address lease time passes.

Note:

If a device can have both IPv4 and IPv6 addresses, you can reserve one IPv4 address and one IPv6 address for the device.

To search for DHCP clients:

  1. Click the funnel icon on the top right corner.
  2. Select one of the search criteria below:
    • All: List all the DHCP clients and DHCP reservations.
    • DHCP clients: List all the DHCP clients with reserved or unreserved IP addresses.
    • DHCP reservations: List all reserved IP addresses. A reserved IP address may not be paired with any device yet.

DHCP Options

After you specify the DHCP options, your Synology NAS as the DHCP server can send out related information to the DHCP clients in a certain subnet.

To specify DHCP options for a subnet:

  1. Go to Control Panel > DHCP Server > Network Interface.
  2. Select the desired network interface and click Edit.
  3. Go to DHCP Server and go to the Subnet list.
  4. Do either action below:
    • To specify DHCP options for an existing subnet: Select the desired interface and click Edit.
    • To create a subnet and specify its DHCP options: Click Add and specify the subnet settings.
  5. Select the wanted DHCP options; to specify the corresponding values, click on the blank fields for editing.
  6. Click OK.

For the supported DHCP options and their value limitations, please refer to the table below:

Code Name Limitation
7 log-server One or multiple IP addresses
9 lpr-server One or multiple IP addresses
13 boot-file-size An integer between 0 and 65536
16 swap-server IP address
17 root-path File path
18 extension-path File path
19 ip-forward-enable 0 or 1
20 non-local-source-routing 0 or 1
21 policy-filter One or multiple pairs of [IP address,Netmask]
Example:192.168.1.1,255.255.255.0
22 max-datagram-reassembly An integer between 576 and 65536
23 default-ttl An integer between 1 and 255
26 mtu An integer between 68 and 65536
27 all-subnets-local 0 or 1
31 router-discovery 0 or 1
32 router-solicitation IP address
34 trailer-encapsulation 0 or 1
35 arp-timeout An integer between 0 and 4294967296
36 ethernet-encap 0 or 1
37 tcp-ttl An integer between 1 and 255
38 tcp-keepalive An integer between 0 and 4294967296
40 nis-domain String
41 nis-server One or multiple IP addresses
42 ntp-server One or multiple IP addresses
44 netbois-ns One or multiple IP addresses
45 netbios-dd One or multiple IP addresses
46 netbios-nodetype 1, 2, 4, or 8
47 netbios-scope String
48 x-windows-fs One or multiple IP addresses
49 x-windows-dm One or multiple IP addresses
58 T1 An integer between 0 and 4294967296
59 T2 An integer between 0 and 4294967296
64 nis+-domain String
65 nis+-server One or multiple IP addresses
68 mobile-ip-home One or multiple IP addresses
69 smtp-server One or multiple IP addresses
70 pop3-server One or multiple IP addresses
71 nntp-server One or multiple IP addresses
74 irc-server One or multiple IP addresses
120 sip-server One or multiple IP addresses
121 classless-static-route One ore multiple pairs of [IP address/0-32,gateway IP]
Example:192.168.1.0/24,192.168.1.254

Vendor

DHCP clients of different vendors may require additional DHCP information. By setting up DHCP options for the vendors, your Synology NAS can provide such details to the clients.

To know the DHCP options supported by each vendor, please contact the specific vendors for details.

To add vendors:

  1. Go to Control Panel > DHCP Server > Vendor.
  2. Click Create to specify the vendor and its DHCP options:
    • Name: Specify the vendor’s name.
    • Code: Specify the numeric code of the DHCP option.
    • Value: Specify the option value.
    • +: Add a DHCP option.
    • : Delete a DHCP option.
  3. Click Create to finish the setup.

To edit DHCP options for vendors:

  1. Go to Control Panel > DHCP Server > Vendor.
  2. Select the desired vendor and click Edit to manage its DHCP options.
  3. Click OK.

PXE

Your Synology NAS can act as a DHCP server to implement the setup of PXE (Pre-Boot Execution Environment). PXE is a network environment that allows client devices to boot up using a network interface rather than a data storage device (e.g. hard disks).

When PXE is implemented, a boot loader can be stored on your Synology NAS or a remote TFTP server, and client devices can boot up over the network using the boot loader.

To use your Synology NAS as a boot loader server:

  1. Make sure you have selected Enable TFTP service (at Control Panel > File Services > TFTP).
  2. Select a folder that hosts the boot loader file as the TFTP root folder.
  3. Make sure at least one DHCP subnet is enabled (at Control Panel > DHCP Server > Network Interface).
  4. Go to Control Panel > DHCP Server > PXE.
  5. Select Enable PXE (Pre-boot Execution Environment).
  6. Select Local TFTP server and select the boot loader file.
  7. Click Apply to save the settings.

To use remote TFTP server as a boot loader server:

By using a remote TFTP server as a boot loader server, you can allow clients to boot up without having to change the current network infrastructure.

  1. Make sure at least one DHCP subnet is enabled (at Control Panel > DHCP Server > Network Interface).
  2. Go to Control Panel > DHCP Server > PXE.
  3. Select Enable PXE (Pre-boot Execution Environment).
  4. Select Remote TFTP server, and specify the server IP address and the file path of the boot loader file.
  5. Click Apply to save the settings.



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