DHCP reservations for SMA clients

Pjohnson · July 2021

I'd like to simplify the process of identifying SMA connect tunnel end users. Has anyone configured DHCP reservations (from the SMA or another device)?

Support indicates the SMA caches connection IPs but they're subject to expiration. It seems my options are to 1) use local accounts or 2) configure an AD attribute to an SMA resource variable to be used in SMA log files.

Perhaps the API would help here.

Any suggestions?

Ajishlal · July 2021

Hi @Pjohnson ,

Hmm got the pain point. In this case we cannot use the Windows DHCP server for reserving the IP for client but we can resolve this issue with LINUX based DHCP Server.

In Linux based DHCP Server, you can reserve IP in DHCP pool by hostname & not required MAC address.

For Example you have to configure the Linux DHCP Server as same as below for reserving the IP based on the host name.

# dhcpd.conf
#
# Sample configuration file for SMA dhcpd
#
# Attention: If /etc/ltsp/dhcpd.conf exists, that will be used as
# configuration file instead of this file.
#

# option definitions common to all supported networks...
option domain-name "test.local";
option domain-name-servers 8.8.8.8;

default-lease-time 86400;
max-lease-time 86400;
ddns-update-style none;
authoritative;

class "test1" {
  match if ( option host-name = "test1");
}
class "test2" {
  match if ( option host-name = "test2");
}
class "test3" {
  match if ( option host-name = "test3");
}

subnet 192.168.0.0 netmask 255.255.0.0 {
  option routers 192.168.0.1;

  pool {
    allow members of "test1";
    range 192.168.1.1 192.168.1.1;
    }
  pool {
    allow members of "test2";
    range 192.168.1.2 192.168.1.2;
    }
  pool {
    allow members of "test3";
    range 192.168.1.3 192.168.1.3;
    }
}

Ajishlal · July 2021

Hi @Pjohnson,

If you have internal DHCP Server (Windows), it's possible to do the DHCP reservation based on the the client MAC address.

Pjohnson · July 2021

Support suggests that SMA doesn't forward MAC. Has your experience been different?

Ajishlal · July 2021

Hi @Pjohnson

A new option is available on SMA appliances running newest firmware, which is NetExtender with dynamic IP address scope (DHCP).

This feature simplify and unifies functionality of NetExtender clients connectivity. Scope can be taken either from internal DHCP server or from devices providing such functionality.

https://www.sonicwall.com/pt-br/support/knowledge-base/how-to-configure-sma-netextender-clients-based-on-dynamic-ip-address-dhcp-scope/170502578296394/

Pjohnson · July 2021

This explains how to pass DHCP requests to another server. How can I configure static reservations if the MAC address isn't forwarded from the SMA/connect tunnel to the DHCP server?

Ajishlal · July 2021

Hi @Pjohnson

Yes. Once you configure the internal server in SMA for passing the DHCP request for the NetExtender clients,

Open DHCP, right click on Reservations and then click on “New Reservation” to create a new reservation of an IP address for a particular Netextender client MAC address. 2. On New Reservation console, enter the reservation name, IP address, and MAC address. Click on Add to create this reservation.

For getting the NetExtender client MAC from Windows Machine, enter the below command and it will show you the NetExtender MAC. Add this MAC address in your internal DHCP Server IP reservation and try.

Pjohnson · July 2021

Connect Tunnel has no MAC!

Pjohnson · July 2021

Thanks very much. I'll give that a try.

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DHCP reservations for SMA clients

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