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ansible/roles/os_hardening/tasks/sysctl.yml

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+---
+# CIS 3.x (Netzwerk) / 1.5.x (Kernel-Haertung). Bewusst ueber
+# ansible.builtin.copy + "sysctl --system" statt des ansible.posix.sysctl-
+# Moduls (siehe Kommentar in Kap. 7/README) -- keine Zusatz-Collection als
+# Voraussetzung fuer den Betrieb dieses Playbooks.
+
+- name: Kernel-/Netzwerk-Haertung (sysctl)
+  ansible.builtin.copy:
+    dest: /etc/sysctl.d/99-jumphost-hardening.conf
+    owner: root
+    group: root
+    mode: "0644"
+    content: |
+      # --- Netzwerk (CIS 3.x) ---
+      net.ipv4.conf.all.rp_filter = 1
+      net.ipv4.conf.default.rp_filter = 1
+      net.ipv4.conf.all.accept_redirects = 0
+      net.ipv4.conf.default.accept_redirects = 0
+      net.ipv4.conf.all.secure_redirects = 0
+      net.ipv4.conf.default.secure_redirects = 0
+      net.ipv4.conf.all.send_redirects = 0
+      net.ipv4.conf.default.send_redirects = 0
+      net.ipv4.conf.all.accept_source_route = 0
+      net.ipv4.conf.default.accept_source_route = 0
+      net.ipv4.conf.all.log_martians = 1
+      net.ipv4.conf.default.log_martians = 1
+      net.ipv4.icmp_echo_ignore_broadcasts = 1
+      net.ipv4.icmp_ignore_bogus_error_responses = 1
+      net.ipv4.tcp_syncookies = 1
+      net.ipv4.ip_forward = 0
+      net.ipv6.conf.all.accept_redirects = 0
+      net.ipv6.conf.default.accept_redirects = 0
+      net.ipv6.conf.all.accept_source_route = 0
+      net.ipv6.conf.default.accept_source_route = 0
+      {% if os_hardening_disable_ipv6 %}
+      net.ipv6.conf.all.disable_ipv6 = 1
+      net.ipv6.conf.default.disable_ipv6 = 1
+      {% endif %}
+      # --- Kernel-Haertung (CIS 1.5.x) ---
+      kernel.kptr_restrict = 2
+      kernel.dmesg_restrict = 1
+      kernel.randomize_va_space = 2
+      kernel.yama.ptrace_scope = 1
+      fs.suid_dumpable = 0
+      fs.protected_hardlinks = 1
+      fs.protected_symlinks = 1
+      fs.protected_fifos = 2
+      fs.protected_regular = 2
+  notify: apply sysctl
+
+- name: Core Dumps zusaetzlich auf PAM-Ebene deaktivieren (CIS 1.5.1)
+  ansible.builtin.copy:
+    dest: /etc/security/limits.d/99-jumphost-no-coredumps.conf
+    owner: root
+    group: root
+    mode: "0644"
+    content: |
+      * hard core 0