Commit c9f9e0e1 authored by Jiri Pirko's avatar Jiri Pirko Committed by Pablo Neira Ayuso

netfilter: doc: add nf_conntrack sysctl api documentation

I grepped through the code and picked bits about nf_conntrack sysctl api
and put that into one documentation file.

[ I have mangled this patch including comments from several grammar
  improvements proposed by Neal Murphy <neal.p.murphy@alum.wpi.edu>,
  any new grammar error is my mistake --pablo ]
Signed-off-by: default avatarJiri Pirko <jiri@resnulli.us>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent e7db3cbc
/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 (read-only)
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 but the hash table will
never have fewer than 32 or more than 16384 buckets.
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
not 0 - enabled (default)
If this option is enabled, the connection tracking code will
provide userspace with connection tracking events via ctnetlink.
nf_conntrack_events_retry_timeout - INTEGER (seconds)
default 15
This option is only relevant when "reliable connection tracking
events" are used. Normally, ctnetlink is "lossy", that is,
events are normally dropped when userspace listeners can't keep up.
Userspace can request "reliable event mode". When this mode is
active, the conntrack will only be destroyed after the event was
delivered. If event delivery fails, the kernel periodically
re-tries to send the event to userspace.
This is the maximum interval the kernel should use when re-trying
to deliver the destroy event.
A higher number means there will be fewer delivery retries and it
will take longer for a backlog to be processed.
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
protocols.
nf_conntrack_helper - BOOLEAN
0 - disabled
not 0 - enabled (default)
Enable automatic conntrack helper assignment.
nf_conntrack_icmp_timeout - INTEGER (seconds)
default 30
Default for ICMP timeout.
nf_conntrack_icmpv6_timeout - INTEGER (seconds)
default 30
Default for ICMP6 timeout.
nf_conntrack_log_invalid - INTEGER
0 - disable (default)
1 - log ICMP packets
6 - log TCP packets
17 - log UDP packets
33 - log DCCP packets
41 - log ICMPv6 packets
136 - log UDPLITE packets
255 - log packets of any protocol
Log invalid packets of a type specified by value.
nf_conntrack_max - INTEGER
Size of connection tracking table. Default value is
nf_conntrack_buckets value * 4.
nf_conntrack_tcp_be_liberal - BOOLEAN
0 - disabled (default)
not 0 - enabled
Be conservative in what you do, be liberal in what you accept from others.
If it's non-zero, we mark only out of window RST segments as INVALID.
nf_conntrack_tcp_loose - BOOLEAN
0 - disabled
not 0 - enabled (default)
If it is set to zero, we disable picking up already established
connections.
nf_conntrack_tcp_max_retrans - INTEGER
default 3
Maximum number of packets that can be retransmitted without
received an (acceptable) ACK from the destination. If this number
is reached, a shorter timer will be started.
nf_conntrack_tcp_timeout_close - INTEGER (seconds)
default 10
nf_conntrack_tcp_timeout_close_wait - INTEGER (seconds)
default 60
nf_conntrack_tcp_timeout_established - INTEGER (seconds)
default 432000 (5 days)
nf_conntrack_tcp_timeout_fin_wait - INTEGER (seconds)
default 120
nf_conntrack_tcp_timeout_last_ack - INTEGER (seconds)
default 30
nf_conntrack_tcp_timeout_max_retrans - INTEGER (seconds)
default 300
nf_conntrack_tcp_timeout_syn_recv - INTEGER (seconds)
default 60
nf_conntrack_tcp_timeout_syn_sent - INTEGER (seconds)
default 120
nf_conntrack_tcp_timeout_time_wait - INTEGER (seconds)
default 120
nf_conntrack_tcp_timeout_unacknowledged - INTEGER (seconds)
default 300
nf_conntrack_timestamp - BOOLEAN
0 - disabled (default)
not 0 - enabled
Enable connection tracking flow timestamping.
nf_conntrack_udp_timeout - INTEGER (seconds)
default 30
nf_conntrack_udp_timeout_stream2 - INTEGER (seconds)
default 180
This extended timeout will be used in case there is an UDP stream
detected.
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