diff --git a/install_files/ansible-base/group_vars/all/securedrop b/install_files/ansible-base/group_vars/all/securedrop
index 218baf1f8f..a9be5850b9 100644
--- a/install_files/ansible-base/group_vars/all/securedrop
+++ b/install_files/ansible-base/group_vars/all/securedrop
@@ -45,3 +45,6 @@ securedrop_pkg_grsec_xenial:
 securedrop_pkg_grsec_focal:
   ver: "5.4.97"
   depends: "linux-image-5.4.97-grsec-securedrop,intel-microcode"
+
+# Mostly useful for local package installation
+grsec_version: "{{ securedrop_pkg_grsec_xenial.ver if securedrop_target_distribution == 'xenial' else securedrop_pkg_grsec_focal.ver }}"
diff --git a/install_files/ansible-base/group_vars/securedrop_application_server.yml b/install_files/ansible-base/group_vars/securedrop_application_server.yml
index e81244a649..c5f9c6b196 100644
--- a/install_files/ansible-base/group_vars/securedrop_application_server.yml
+++ b/install_files/ansible-base/group_vars/securedrop_application_server.yml
@@ -9,6 +9,7 @@ local_deb_packages:
   - "securedrop-keyring-0.1.4+{{ securedrop_version }}+{{ securedrop_target_distribution }}-amd64.deb"
   - "securedrop-config-0.1.4+{{ securedrop_version }}+{{ securedrop_target_distribution }}-amd64.deb"
   - "securedrop-ossec-agent-3.6.0+{{ securedrop_version }}+{{ securedrop_target_distribution }}-amd64.deb"
+  -  securedrop-grsec-{{ grsec_version }}+{{ securedrop_target_distribution }}-amd64.deb
   - "{{ securedrop_app_code_deb }}.deb"
   - "ossec-agent-3.6.0+{{ securedrop_target_distribution }}-amd64.deb"
 
diff --git a/install_files/ansible-base/group_vars/securedrop_monitor_server.yml b/install_files/ansible-base/group_vars/securedrop_monitor_server.yml
index ed4a28eeb7..73ab530daa 100644
--- a/install_files/ansible-base/group_vars/securedrop_monitor_server.yml
+++ b/install_files/ansible-base/group_vars/securedrop_monitor_server.yml
@@ -9,6 +9,7 @@ local_deb_packages:
   - "securedrop-keyring-0.1.4+{{ securedrop_version }}+{{ securedrop_target_distribution }}-amd64.deb"
   - "securedrop-config-0.1.4+{{ securedrop_version }}+{{ securedrop_target_distribution }}-amd64.deb"
   - "securedrop-ossec-server-3.6.0+{{ securedrop_version }}+{{ securedrop_target_distribution }}-amd64.deb"
+  - securedrop-grsec-{{ grsec_version }}+{{ securedrop_target_distribution }}-amd64.deb
   - ossec-server-3.6.0+{{ securedrop_target_distribution }}-amd64.deb
 
 # Configure the tor onion services. The Monitor server has only one,
diff --git a/install_files/ansible-base/roles/common/defaults/main.yml b/install_files/ansible-base/roles/common/defaults/main.yml
index 3850dd4208..d2c3ae7a38 100644
--- a/install_files/ansible-base/roles/common/defaults/main.yml
+++ b/install_files/ansible-base/roles/common/defaults/main.yml
@@ -38,6 +38,9 @@ sysctl_flags:
     value: "0"
   - name: "net.ipv4.conf.default.send_redirects"
     value: "0"
+
+# Store IPv6-related sysctl flags separately, for distro-specific handling
+sysctl_flags_ipv6:
   - name: "net.ipv6.conf.all.disable_ipv6"
     value: "1"
   - name: "net.ipv6.conf.default.disable_ipv6"
diff --git a/install_files/ansible-base/roles/common/tasks/post_ubuntu_install_checks.yml b/install_files/ansible-base/roles/common/tasks/post_ubuntu_install_checks.yml
index e562304c03..d2b82eddd2 100644
--- a/install_files/ansible-base/roles/common/tasks/post_ubuntu_install_checks.yml
+++ b/install_files/ansible-base/roles/common/tasks/post_ubuntu_install_checks.yml
@@ -53,22 +53,16 @@
   tags:
     - ntp
 
-- name: Disable VirtualBox service vboxadd to avoid conflict with systemd-timesyncd.
+- name: Disable VirtualBox services to avoid conflict with systemd-timesyncd.
   systemd:
-    name: vboxadd
-    enabled: no
-    state: stopped
-  when: ansible_distribution_release == "focal"
-  become: yes
-  tags:
-    - ntp
-
-- name: Disable VirtualBox service vboxadd-service to avoid conflict with systemd-timesyncd.
-  systemd:
-    name: vboxadd-service
+    name: "{{ item }}"
     enabled: no
     state: stopped
   when: ansible_distribution_release == "focal"
+  failed_when: false
+  with_items:
+    - vboxadd
+    - vboxadd-service
   become: yes
   tags:
     - ntp
diff --git a/install_files/ansible-base/roles/common/tasks/sysctl.yml b/install_files/ansible-base/roles/common/tasks/sysctl.yml
index e05adc5415..5c542cb4ea 100644
--- a/install_files/ansible-base/roles/common/tasks/sysctl.yml
+++ b/install_files/ansible-base/roles/common/tasks/sysctl.yml
@@ -12,3 +12,16 @@
   tags:
     - sysctl
     - hardening
+
+- name: Set sysctl flags for net.ipv6 config.
+  sysctl:
+    name: "{{ item.name }}"
+    value: "{{ item.value }}"
+    sysctl_set: yes
+    state: present
+    reload: yes
+  with_items: "{{ sysctl_flags_ipv6 }}"
+  when: ansible_distribution_release == "xenial"
+  tags:
+    - sysctl
+    - hardening
diff --git a/install_files/ansible-base/roles/grsecurity/tasks/from_local_pkg_install_grsec.yml b/install_files/ansible-base/roles/grsecurity/tasks/from_local_pkg_install_grsec.yml
index adfe2e5b70..71bf11f9fa 100644
--- a/install_files/ansible-base/roles/grsecurity/tasks/from_local_pkg_install_grsec.yml
+++ b/install_files/ansible-base/roles/grsecurity/tasks/from_local_pkg_install_grsec.yml
@@ -1,12 +1,11 @@
 ---
-- name: Get the grsec version of the current scenario
-  set_fact:
-    grsec_version: "{% if ansible_distribution_release == 'xenial' %}{{ securedrop_pkg_grsec_xenial.ver }}{% else %}{{ securedrop_pkg_grsec_focal.ver }}{% endif %}"
-
 - name: Copy locally built securedrop-grsec metapackage
   copy:
     src: "../../build/{{ securedrop_target_distribution }}/securedrop-grsec-{{ grsec_version }}+{{ securedrop_target_distribution }}-amd64.deb"
-    dest: /root/securedrop-grsec.deb
+    dest: "/root/securedrop-grsec-{{ grsec_version }}+{{ securedrop_target_distribution }}-amd64.deb"
 
 - name: Install locally built securedrop-grsec metapackage
-  command: apt-get install -y -f /root/securedrop-grsec.deb
+  command: apt-get install -y -f "/root/securedrop-grsec-{{ grsec_version }}+{{ securedrop_target_distribution }}-amd64.deb"
+
+- name: Mark package as held, so it doesn't update to apt-test version
+  command: apt-mark hold securedrop-grsec
diff --git a/install_files/ansible-base/roles/install-local-packages/tasks/hold_debs.yml b/install_files/ansible-base/roles/install-local-packages/tasks/hold_debs.yml
index 063f0411ed..1a1e604c77 100644
--- a/install_files/ansible-base/roles/install-local-packages/tasks/hold_debs.yml
+++ b/install_files/ansible-base/roles/install-local-packages/tasks/hold_debs.yml
@@ -13,9 +13,5 @@
 - name: Mark packages as held, so they aren't upgraded automatically (via apt).
   command: apt-mark hold {{ item.stdout }}
   register: apt_mark_hold_result
-  # The packages will have the "hold" state cleared during the previous task
-  # for `dpkg -i <deb>`. Therefore let's determine changed state by comparing
-  # to the value prior to installation.
-  changed_when: item.stdout not in apt_mark_showhold_result.stdout_lines
-  when: item.stdout not in apt_mark_showhold_result.stdout_lines
+  changed_when: not apt_mark_showhold_result.stdout.endswith("was already set on hold")
   with_items: "{{ local_deb_packages_name_check.results }}"
diff --git a/install_files/securedrop-grsec-focal/DEBIAN/postinst.j2 b/install_files/securedrop-grsec-focal/DEBIAN/postinst.j2
index 6d251e9b03..88c20a1172 100755
--- a/install_files/securedrop-grsec-focal/DEBIAN/postinst.j2
+++ b/install_files/securedrop-grsec-focal/DEBIAN/postinst.j2
@@ -28,7 +28,7 @@ set_grub_default() {
     # When using CONFIG_PAX_KERNEXEC, the grsecurity team recommends the kernel
     # is booted with "noefi" on the kernel command line if "CONFIG_EFI" is
     # enabled, as EFI runtime services are necessarily mapped as RWX.
-    sed -i '/^GRUB_CMDLINE_LINUX_DEFAULT=/s/=.*/=\"noefi\"/' /etc/default/grub
+    sed -i '/^GRUB_CMDLINE_LINUX_DEFAULT=/s/=.*/=\"noefi ipv6\.disable=1 quiet\"/' /etc/default/grub
     update-grub
 }
 
diff --git a/molecule/testinfra/common/test_automatic_updates.py b/molecule/testinfra/common/test_automatic_updates.py
index 63746bcf4b..fd4d016ec4 100644
--- a/molecule/testinfra/common/test_automatic_updates.py
+++ b/molecule/testinfra/common/test_automatic_updates.py
@@ -243,7 +243,7 @@ def test_unattended_upgrades_functional(host):
     are up-to-date.
     """
     if host.system_info.codename != "xenial":
-        c = host.run('sudo unattended-upgrades -d')
+        c = host.run('sudo unattended-upgrades --dry-run --debug')
         assert c.rc == 0
         expected_origins = (
             "Allowed origins are: origin=Ubuntu,archive=focal, origin=Ubuntu,archive=focal-security"
diff --git a/molecule/testinfra/common/test_grsecurity.py b/molecule/testinfra/common/test_grsecurity.py
index 6b4af061e0..3bf05d23df 100644
--- a/molecule/testinfra/common/test_grsecurity.py
+++ b/molecule/testinfra/common/test_grsecurity.py
@@ -277,3 +277,15 @@ def test_mds_mitigations_and_smt_disabled(host):
         grub_config = host.file(grub_config_path)
 
         assert grub_config.contains("mds=full,nosmt")
+
+
+def test_kernel_boot_options(host):
+    """
+    Ensure command-line options for currently booted kernel are set.
+    """
+    with host.sudo():
+        f = host.file("/proc/cmdline")
+        boot_opts = f.content_string.split()
+    assert "noefi" in boot_opts
+    if host.system_info.codename == "focal":
+        assert "ipv6.disable=1" in boot_opts
diff --git a/molecule/testinfra/common/test_ip6tables.py b/molecule/testinfra/common/test_ip6tables.py
index 8f7497731b..ecc6e29c3f 100644
--- a/molecule/testinfra/common/test_ip6tables.py
+++ b/molecule/testinfra/common/test_ip6tables.py
@@ -4,11 +4,15 @@
 testinfra_hosts = [test_vars.app_hostname, test_vars.monitor_hostname]
 
 
-def test_ip6tables_drop_everything(host):
+def test_ip6tables_drop_everything_xenial(host):
     """
     Ensure that all IPv6 packets are dropped by default.
     The IPv4 rules are more complicated, and tested separately.
+    This test is Xenial-specific, given that on Focal we disable
+    IPv6 functionality completely.
     """
+    if host.system_info.codename != "xenial":
+        return True
     desired_ip6tables_output = """
 -P INPUT DROP
 -P FORWARD DROP
@@ -18,3 +22,26 @@ def test_ip6tables_drop_everything(host):
     with host.sudo():
         c = host.check_output("ip6tables -S")
         assert c == desired_ip6tables_output
+
+
+def test_ip6tables_drop_everything_focal(host):
+    """
+    Ensures that IPv6 firewall settings are inaccessible,
+    due to fully disabling IPv6 functionality at boot-time,
+    via boot options.
+    """
+    if host.system_info.codename != "focal":
+        return True
+    with host.sudo():
+        c = host.run("ip6tables -S")
+        assert c.rc != 0
+        assert c.stdout == ""
+
+
+def test_ipv6_addresses_absent(host):
+    """
+    Ensure that no IPv6 addresses are assigned to interfaces.
+    """
+    with host.sudo():
+        c = host.check_output("ip -6 addr")
+        assert c == ""
diff --git a/molecule/testinfra/common/test_system_hardening.py b/molecule/testinfra/common/test_system_hardening.py
index 283e49a840..d7825a3bd7 100644
--- a/molecule/testinfra/common/test_system_hardening.py
+++ b/molecule/testinfra/common/test_system_hardening.py
@@ -33,6 +33,9 @@ def test_sysctl_options(host, sysctl_opt):
     due to the heavy use of Tor.
     """
     with host.sudo():
+        # For Focal, we disable IPv6 entirely, so the IPv6 sysctl options won't exist
+        if sysctl_opt[0].startswith("net.ipv6") and host.system_info.codename == "focal":
+            return True
         assert host.sysctl(sysctl_opt[0]) == sysctl_opt[1]