{"description": "To set the runtime status of the <code>net.ipv4.conf.default.forwarding</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.forwarding=0</pre>\nTo make sure that the setting is persistent, add the following line to a file in the directory <tt>/etc/sysctl.d</tt>: <pre>net.ipv4.conf.default.forwarding = 0</pre>", "rationale": "IP forwarding permits the kernel to forward packets from one network\ninterface to another. The ability to forward packets between two networks is\nonly appropriate for systems acting as routers.", "severity": "medium", "references": {}, "control_references": {}, "components": [], "identifiers": {}, "ocil_clause": "IP forwarding value is \"1\" and the system is not router", "ocil": "The runtime status of the <code>net.ipv4.conf.default.forwarding</code> kernel parameter can be queried\nby running the following command:\n<pre>$ sysctl net.ipv4.conf.default.forwarding</pre>\n<code>0</code>.\nThe ability to forward packets is only appropriate for routers.", "oval_external_content": null, "fixtext": "Configure Ubuntu 22.04 to not allow packet forwarding unless the system is a router with the following commands:\nAdd or edit the following line in a system configuration file in the \"/etc/sysctl.d/\" directory:\nnet.ipv4.conf.default.forwarding = 0\n\nLoad settings from all system configuration files with the following command:\n\n$ sudo sysctl --system", "checktext": "", "vuldiscussion": "", "srg_requirement": "Ubuntu 22.04 must not perform packet forwarding unless the system is a router.", "warnings": [{"general": "There might be cases when certain applications can systematically override this option.\nOne such case is <a xmlns='http://www.w3.org/1999/xhtml' href='https://libvirt.org/'>Libvirt</a>; a toolkit for managing of virtualization platforms.\nBy default, Libvirt requires IP forwarding to be enabled to facilitate\nnetwork communication between the virtualization host and guest\nmachines. It enables IP forwarding after every reboot."}], "conflicts": [], "requires": [], "policy_specific_content": {}, "platform": "system_with_kernel", "platforms": ["system_with_kernel"], "sce_metadata": {"check-import": "stdout", "check-export": ["sysctl_net_ipv4_conf_default_forwarding_value=xccdf_org.ssgproject.content_value_sysctl_net_ipv4_conf_default_forwarding_value"], "platform": ["multi_platform_all"], "environment": "any", "filename": "sysctl_net_ipv4_conf_default_forwarding.sh", "relative_path": "ubuntu2204/checks/sce/sysctl_net_ipv4_conf_default_forwarding.sh"}, "inherited_platforms": ["system_with_kernel"], "cpe_platform_names": ["system_with_kernel"], "inherited_cpe_platform_names": ["system_with_kernel"], "bash_conditional": null, "fixes": {}, "title": "Disable Kernel Parameter for IPv4 Forwarding By Default", "definition_location": "/aptdata/openscap/scap-security-guide/linux_os/guide/system/network/network-kernel/network_host_and_router_parameters/sysctl_net_ipv4_conf_default_forwarding/rule.yml", "template": {"name": "sysctl", "vars": {"sysctlvar": "net.ipv4.conf.default.forwarding", "datatype": "int"}, "backends": {}}}