What is securelevel?
The securelevel is a security mechanism implemented in the kernel. Basically, when the securelevel is positive, the kernel restricts certain tasks; not even the superuser (i.e., root) is allowed to do them. At the time of this writing, the securelevel mechanism is capable of, among other things, limiting the ability to: • Unset certain file flags, such as schg (the system immutable flag). • Write to kernel memory via /dev/mem and /dev/kmem. • Load kernel modules. • Alter firewall rules.
The securelevel is a security mechanism implemented in the kernel. Basically, when the securelevel is positive, the kernel restricts certain tasks; not even the superuser (i.e., root) is allowed to do them. At the time of this writing, the securelevel mechanism is capable of, among other things, limiting the ability to, • unset certain file flags, such as schg (the system immutable flag), • write to kernel memory via /dev/mem and /dev/kmem, • load kernel modules, and • alter firewall rules.
The securelevel is a security mechanism implemented in the kernel. Basically, when the securelevel is positive, the kernel restricts certain tasks; not even the superuser (i.e., root) is allowed to do them. At the time of this writing, the securelevel mechanism is capable of, among other things, limiting the ability to, • unset certain file flags, such as schg (the system immutable flag), • write to kernel memory via /dev/mem and /dev/kmem, • load kernel modules, and • alter ipfirewall(4) rules.
The securelevel is a security mechanism implemented in the kernel. Basically, when the securelevel is positive, the kernel restricts certain tasks; not even the superuser (i.e., root) is allowed to do them. At the time of this writing, the securelevel mechanism is capable of, among other things, limiting the ability to, * unset certain file flags, such as schg (the system immutable flag), * write to kernel memory via /dev/mem and /dev/kmem, * load kernel modules, and * alter firewall rules. To check the status of the securelevel on a running system, simply execute the following command: # sysctl kern.securelevel The output will contain the name of the sysctl(8) variable (in this case, kern.securelevel) and a number. The latter is the current value of the securelevel. If it is positive (i.e., greater than 0), at least some of the securelevel’s protections are enabled. You cannot lower the securelevel of a running system; being able to do that would defeat its purpose. If you need to do
The securelevel is a security mechanism implemented in the kernel. Basically, when the securelevel is positive, the kernel restricts certain tasks; not even the superuser (i.e., root) is allowed to do them. At the time of this writing, the securelevel mechanism is capable of, among other things, limiting the ability to, unset certain file flags, such as schg (the system immutable flag), write to kernel memory via /dev/mem and /dev/kmem, load kernel modules, and alter ipfirewall(4) rules. To check the status of the securelevel on a running system, simply execute the following command: # sysctl kern.securelevel The output will contain the name of the sysctl(8) variable (in this case, kern.securelevel) and a number. The latter is the current value of the securelevel. If it is positive (i.e., greater than 0), at least some of the securelevel’s protections are enabled. You cannot lower the securelevel of a running system; being able to do that would defeat its purpose. If you need to do a t
