41 lines
1.9 KiB
Plaintext
41 lines
1.9 KiB
Plaintext
This menu allows you to configure the Securelevel mechanism in FreeBSD.
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Securelevels may be used to limit the privileges assigned to the
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root user in multi-user mode, which in turn may limit the effects of
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a root compromise, at the cost of reducing administrative functions.
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Refer to the security(7) and init(8) manual pages for complete details.
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-1 Permanently insecure mode - always run the system in level 0
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mode. This is the default initial value.
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0 Insecure mode - immutable and append-only flags may be turned
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off. All devices may be read or written subject to their
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permissions.
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1 Secure mode - the system immutable and system append-only
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flags may not be turned off; disks for mounted file systems,
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/dev/mem, /dev/kmem and /dev/io (if your platform has it)
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may not be opened for writing; kernel modules (see kld(4))
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may not be loaded or unloaded.
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2 Highly secure mode - same as secure mode, plus disks may not
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be opened for writing (except by mount(2)) whether mounted or
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not. This level precludes tampering with file systems by
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unmounting them, but also inhibits running newfs(8) while the
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system is multi-user.
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In addition, kernel time changes are restricted to less than
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or equal to one second. Attempts to change the time by more
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than this will log the message ``Time adjustment clamped to +1
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second''.
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3 Network secure mode - same as highly secure mode, plus IP
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packet filter rules (see ipfw(8), ipfirewall(4) and pfctl(8))
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cannot be changed and dummynet(4) or pf(4) configuration
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cannot be adjusted.
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Securelevels must be used in combination with careful system design and
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application of protective mechanisms to prevent system configuration
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files from being modified in a way that compromises the protections of
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the securelevel variable upon reboot.
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