pfSense

Below is an example of possible options with the right syntax:

https://github.com/isc-projects/kea/blob/master/doc/examples/kea4/all-options.json

I'm providing a patch here to experiment with custom options for DHCP4; no support will be provided for this. ShowHide

diff --git a/src/etc/inc/services.inc b/src/etc/inc/services.inc
index 62cbcd4e40..48c90ee690 100644
--- a/src/etc/inc/services.inc
+++ b/src/etc/inc/services.inc
@@ -1221,6 +1221,22 @@ function services_kea4_configure() {
     $dhcpdcfg = config_get_path('dhcpd');
     $Iflist = get_configured_interface_list();

+    /* custom options */
+    $kea_custom_options_set = false;
+    $kea_custom_options_config = config_get_path('kea/custom_options_patch');
+    if (!empty($kea_custom_options_config)) {
+        $kea_custom_options_config = base64_decode($kea_custom_options_config);
+        if (is_string($kea_custom_options_config)) {
+            $kea_custom_options_set = true;
+        }
+    }
+    if ($kea_custom_options_set) {
+        $kea_custom_options_config = json_decode($kea_custom_options_config, true);
+        if (empty($kea_custom_options_config) || !is_array($kea_custom_options_config)) {
+            $kea_custom_options_set = false;
+        }
+    }
+
     /* configuration is built as a PHP array and converted to json */
     $keaconf = [];
     $keaconf['Dhcp4'] = [
@@ -1265,6 +1281,13 @@ function services_kea4_configure() {
         ],
     ];

+    /* custom option definitions */
+    if ($kea_custom_options_set) {
+        foreach ($kea_custom_options_config['option-def'] as $option_def) {
+            $keaconf['Dhcp4']['option-def'][] = $option_def;
+        }
+    }
+
     /* See https://redmine.pfsense.org/issues/15328 */
     $keaconf['Dhcp4']['sanity-checks'] = [
         'lease-checks' => 'fix-del'
@@ -1504,6 +1527,16 @@ function services_kea4_configure() {
             $all_pools = array_merge($all_pools, $dhcpifconf['pool']);
         }

+        /* custom option data */
+        if ($kea_custom_options_set) {
+            foreach (array_get_path($kea_custom_options_config, "option-data/all", []) as $custom_option_data) {
+                $keasubnet['option-data'][] = $custom_option_data;
+            }
+            foreach (array_get_path($kea_custom_options_config, "option-data/{$dhcpif}", []) as $custom_option_data) {
+                $keasubnet['option-data'][] = $custom_option_data;
+            }
+        }
+
         if ($dhcpifconf['domain']) {
             $keasubnet['option-data'][] = [
                 'name' => 'domain-name',
diff --git a/src/usr/local/www/services_dhcp_settings.php b/src/usr/local/www/services_dhcp_settings.php
index b219460f5c..aa5f352363 100644
--- a/src/usr/local/www/services_dhcp_settings.php
+++ b/src/usr/local/www/services_dhcp_settings.php
@@ -61,6 +61,21 @@ if ($_POST['apply']) {
 } elseif ($_POST['act']) {
     switch($_POST['act']) {
     case 'save':
+        /* custom options config */
+        if (!empty($_POST['custom_options_patch'])) {
+            $temp_data = json_decode($_POST['custom_options_patch'], true);
+            if (is_array($temp_data) && !empty($temp_data)) {
+                array_set_path($pconfig, 'custom_options_patch', base64_encode($_POST['custom_options_patch']));
+                config_set_path('kea/custom_options_patch', base64_encode($_POST['custom_options_patch']));
+                write_config("DHCP Server - added custom options");
+                mark_subsystem_dirty('dhcpd');
+            }
+        } elseif (config_get_path('kea/custom_options_patch') !== null) {
+            array_del_path($pconfig, 'custom_options_patch');
+            config_del_path('kea/custom_options_patch');
+            write_config("DHCP Server - removed custom options");
+            mark_subsystem_dirty('dhcpd');
+        }
         [$input_errors, $pconfig] = dhcp_do_settings_post($subnets);
         $subnets = kea_build_subnet_list(); /* refresh subnet list */
         break;
@@ -342,6 +357,15 @@ $section->addInput(new Form_Select(

 $form->add($section);

+/* custom options input */
+$section = new Form_Section(gettext('Custom Options'));
+$section->addInput(new Form_Textarea(
+    'custom_options_patch',
+    'JSON Data',
+    ((array_get_path($pconfig, 'custom_options_patch') !== null) ? base64_decode($pconfig['custom_options_patch']) : null)
+));
+$form->add($section);
+
 $form->addGlobal(new Form_Input(
     'act',
     '',

Apply it with the System Patches package, then go to Services > DHCP Server > Settings, enter the JSON-formatted custom option data, then Save/Apply.

The custom option needs to be defined once and applied per interface. Here's an example that adds a vendor option (43) to the opt1 interface (get the name from Status > Interfaces): ShowHide

{
  "option-def": [
    {
      "space": "dhcp4",
      "name": "custom-option-vendor",
      "code": 43,
      "type": "string" 
    }
  ],
  "option-data": {
    "opt1": [
      {
        "name": "custom-option-vendor",
        "data": "01:04:0a:01:01:01" 
      }
    ]
  }
}

I'm test driving this right now.
pfSense 24.11 Release.
With the patch mentioned above.

See also : [[https://forum.netgate.com/topic/190373/feature-15321-shows-how-to-use-option-114-in-kea/4]]

This modification to the patch for Plus release 25.03 Beta is working for me:

diff --git a/src/etc/inc/services.inc b/src/etc/inc/services.inc
index 62cbcd4e40..48c90ee690 100644
--- a/src/etc/inc/services.inc
+++ b/src/etc/inc/services.inc
@@ -1221,6 +1221,22 @@ function services_kea4_configure() {
     $dhcpdcfg = config_get_path('dhcpd');
     $Iflist = get_configured_interface_list();

+    /* custom options */
+    $kea_custom_options_set = false;
+    $kea_custom_options_config = config_get_path('kea/custom_options_patch');
+    if (!empty($kea_custom_options_config)) {
+        $kea_custom_options_config = base64_decode($kea_custom_options_config);
+        if (is_string($kea_custom_options_config)) {
+            $kea_custom_options_set = true;
+        }
+    }
+    if ($kea_custom_options_set) {
+        $kea_custom_options_config = json_decode($kea_custom_options_config, true);
+        if (empty($kea_custom_options_config) || !is_array($kea_custom_options_config)) {
+            $kea_custom_options_set = false;
+        }
+    }
+
     /* configuration is built as a PHP array and converted to json */
     $keaconf = [];
     $keaconf['Dhcp4'] = [
@@ -1265,6 +1281,13 @@ function services_kea4_configure() {
         ],
     ];

+    /* custom option definitions */
+    if ($kea_custom_options_set) {
+        foreach ($kea_custom_options_config['option-def'] as $option_def) {
+            $keaconf['Dhcp4']['option-def'][] = $option_def;
+        }
+    }
+
     /* See https://redmine.pfsense.org/issues/15328 */
     $keaconf['Dhcp4']['sanity-checks'] = [
         'lease-checks' => 'fix-del'
@@ -1504,6 +1527,16 @@ function services_kea4_configure() {
             $all_pools = array_merge($all_pools, $dhcpifconf['pool']);
         }

+        /* custom option data */
+        if ($kea_custom_options_set) {
+            foreach (array_get_path($kea_custom_options_config, "option-data/all", []) as $custom_option_data) {
+                $keasubnet['option-data'][] = $custom_option_data;
+            }
+            foreach (array_get_path($kea_custom_options_config, "option-data/{$dhcpif}", []) as $custom_option_data) {
+                $keasubnet['option-data'][] = $custom_option_data;
+            }
+        }
+
         if ($dhcpifconf['domain']) {
             $keasubnet['option-data'][] = [
                 'name' => 'domain-name',
diff --git a/src/usr/local/www/services_dhcp_settings.php b/src/usr/local/www/services_dhcp_settings.php
index b219460f5c..aa5f352363 100644
--- a/src/usr/local/www/services_dhcp_settings.php
+++ b/src/usr/local/www/services_dhcp_settings.php
@@ -59,6 +59,21 @@ if ($_POST['apply']) {
 } elseif ($_POST['act']) {
     switch($_POST['act']) {
     case 'save':
+        /* custom options config */
+        if (!empty($_POST['custom_options_patch'])) {
+            $temp_data = json_decode($_POST['custom_options_patch'], true);
+            if (is_array($temp_data) && !empty($temp_data)) {
+                array_set_path($pconfig, 'custom_options_patch', base64_encode($_POST['custom_options_patch']));
+                config_set_path('kea/custom_options_patch', base64_encode($_POST['custom_options_patch']));
+                write_config("DHCP Server - added custom options");
+                mark_subsystem_dirty('dhcpd');
+            }
+        } elseif (config_get_path('kea/custom_options_patch') !== null) {
+            array_del_path($pconfig, 'custom_options_patch');
+            config_del_path('kea/custom_options_patch');
+            write_config("DHCP Server - removed custom options");
+            mark_subsystem_dirty('dhcpd');
+        }
        [$input_errors, $pconfig] = dhcp_do_settings_post();
        break;
    default:
@@ -342,6 +357,15 @@ $section->addInput(new Form_Select(

 $form->add($section);

+/* custom options input */
+$section = new Form_Section(gettext('Custom Options'));
+$section->addInput(new Form_Textarea(
+    'custom_options_patch',
+    'JSON Data',
+    ((array_get_path($pconfig, 'custom_options_patch') !== null) ? base64_decode($pconfig['custom_options_patch']) : null)
+));
+$form->add($section);
+
 $form->addGlobal(new Form_Input(
     'act',
     '',

I can already forsee the numerous support posts. Are we relying on the user to correctly identify the spacing issues that will come up? Is there really no way to offer the dhcp options text boxes and then have pfsense format it correctly in json?

No doubt

But what it does do is provide the flexibility now for people that really need it while we take the next steps in removing DHCPD from the base.

There is a tremendous amount of tech debt and overhead trying to make both DHCPs available as options in pfSense. Once we can shed DHCPD for good, we can more cleanly and clearly do the right thing and give Kea the UI it really wants, and the DHCP UI in pfSense today fundamentally isn't it.

Check out ISC Stork for the reference Kea GUI. It's hot. That's where we want to be. This solution here will help get us there. We've recycled what we can from the old UI but we need a transitional UI to help get us to the next phase.

I've created a quick-start guide for this on the forum:
https://forum.netgate.com/topic/196513