Documentation/networking/nf_conntrack-sysctl.rst

Source file repositories/reference/linux-study-clean/Documentation/networking/nf_conntrack-sysctl.rst

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Documentation/networking/nf_conntrack-sysctl.rst
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.. SPDX-License-Identifier: GPL-2.0

===================================
Netfilter Conntrack Sysfs variables
===================================

/proc/sys/net/netfilter/nf_conntrack_* Variables:
=================================================

nf_conntrack_acct - BOOLEAN
	- 0 - disabled (default)
	- not 0 - enabled

	Enable connection tracking flow accounting. 64-bit byte and packet
	counters per flow are added.

nf_conntrack_buckets - INTEGER
	Size of hash table. If not specified as parameter during module
	loading, the default size is calculated by dividing total memory
	by 16384 to determine the number of buckets. The hash table will
	never have fewer than 1024 and never more than 262144 buckets.
	This sysctl is only writeable in the initial net namespace.

nf_conntrack_checksum - BOOLEAN
	- 0 - disabled
	- not 0 - enabled (default)

	Verify checksum of incoming packets. Packets with bad checksums are
	in INVALID state. If this is enabled, such packets will not be
	considered for connection tracking.

nf_conntrack_count - INTEGER (read-only)
	Number of currently allocated flow entries.

nf_conntrack_events - BOOLEAN
	- 0 - disabled
	- 1 - enabled
	- 2 - auto (default)

	If this option is enabled, the connection tracking code will
	provide userspace with connection tracking events via ctnetlink.
	The default allocates the extension if a userspace program is
	listening to ctnetlink events.

nf_conntrack_expect_max - INTEGER
	Maximum size of expectation table.  Default value is
	nf_conntrack_buckets / 256. Minimum is 1.

nf_conntrack_frag6_high_thresh - INTEGER
	default 262144

	Maximum memory used to reassemble IPv6 fragments.  When
	nf_conntrack_frag6_high_thresh bytes of memory is allocated for this
	purpose, the fragment handler will toss packets until
	nf_conntrack_frag6_low_thresh is reached.

nf_conntrack_frag6_low_thresh - INTEGER
	default 196608

	See nf_conntrack_frag6_low_thresh

nf_conntrack_frag6_timeout - INTEGER (seconds)
	default 60

	Time to keep an IPv6 fragment in memory.

nf_conntrack_generic_timeout - INTEGER (seconds)
	default 600

	Default for generic timeout.  This refers to layer 4 unknown/unsupported

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Implementation Notes