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Discussion during NFWS 2017 in Faro has shown that the current
conntrack behaviour is unreasonable.
Even if conntrack module is loaded on behalf of a single net namespace,
its turned on for all namespaces, which is expensive. Commit
481fa37347 ("netfilter: conntrack: add nf_conntrack_default_on sysctl")
attempted to provide an alternative to the 'default on' behaviour by
adding a sysctl to change it.
However, as Eric points out, the sysctl only becomes available
once the module is loaded, and then its too late.
So we either have to move the sysctl to the core, or, alternatively,
change conntrack to become active only once the rule set requires this.
This does the latter, conntrack is only enabled when a rule needs it.
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
164 lines
4.4 KiB
Plaintext
164 lines
4.4 KiB
Plaintext
/proc/sys/net/netfilter/nf_conntrack_* Variables:
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nf_conntrack_acct - BOOLEAN
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0 - disabled (default)
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not 0 - enabled
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Enable connection tracking flow accounting. 64-bit byte and packet
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counters per flow are added.
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nf_conntrack_buckets - INTEGER
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Size of hash table. If not specified as parameter during module
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loading, the default size is calculated by dividing total memory
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by 16384 to determine the number of buckets but the hash table will
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never have fewer than 32 and limited to 16384 buckets. For systems
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with more than 4GB of memory it will be 65536 buckets.
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This sysctl is only writeable in the initial net namespace.
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nf_conntrack_checksum - BOOLEAN
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0 - disabled
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not 0 - enabled (default)
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Verify checksum of incoming packets. Packets with bad checksums are
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in INVALID state. If this is enabled, such packets will not be
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considered for connection tracking.
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nf_conntrack_count - INTEGER (read-only)
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Number of currently allocated flow entries.
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nf_conntrack_events - BOOLEAN
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0 - disabled
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not 0 - enabled (default)
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If this option is enabled, the connection tracking code will
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provide userspace with connection tracking events via ctnetlink.
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nf_conntrack_expect_max - INTEGER
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Maximum size of expectation table. Default value is
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nf_conntrack_buckets / 256. Minimum is 1.
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nf_conntrack_frag6_high_thresh - INTEGER
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default 262144
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Maximum memory used to reassemble IPv6 fragments. When
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nf_conntrack_frag6_high_thresh bytes of memory is allocated for this
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purpose, the fragment handler will toss packets until
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nf_conntrack_frag6_low_thresh is reached.
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nf_conntrack_frag6_low_thresh - INTEGER
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default 196608
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See nf_conntrack_frag6_low_thresh
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nf_conntrack_frag6_timeout - INTEGER (seconds)
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default 60
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Time to keep an IPv6 fragment in memory.
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nf_conntrack_generic_timeout - INTEGER (seconds)
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default 600
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Default for generic timeout. This refers to layer 4 unknown/unsupported
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protocols.
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nf_conntrack_helper - BOOLEAN
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0 - disabled (default)
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not 0 - enabled
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Enable automatic conntrack helper assignment.
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If disabled it is required to set up iptables rules to assign
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helpers to connections. See the CT target description in the
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iptables-extensions(8) man page for further information.
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nf_conntrack_icmp_timeout - INTEGER (seconds)
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default 30
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Default for ICMP timeout.
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nf_conntrack_icmpv6_timeout - INTEGER (seconds)
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default 30
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Default for ICMP6 timeout.
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nf_conntrack_log_invalid - INTEGER
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0 - disable (default)
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1 - log ICMP packets
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6 - log TCP packets
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17 - log UDP packets
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33 - log DCCP packets
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41 - log ICMPv6 packets
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136 - log UDPLITE packets
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255 - log packets of any protocol
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Log invalid packets of a type specified by value.
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nf_conntrack_max - INTEGER
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Size of connection tracking table. Default value is
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nf_conntrack_buckets value * 4.
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nf_conntrack_tcp_be_liberal - BOOLEAN
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0 - disabled (default)
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not 0 - enabled
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Be conservative in what you do, be liberal in what you accept from others.
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If it's non-zero, we mark only out of window RST segments as INVALID.
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nf_conntrack_tcp_loose - BOOLEAN
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0 - disabled
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not 0 - enabled (default)
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If it is set to zero, we disable picking up already established
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connections.
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nf_conntrack_tcp_max_retrans - INTEGER
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default 3
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Maximum number of packets that can be retransmitted without
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received an (acceptable) ACK from the destination. If this number
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is reached, a shorter timer will be started.
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nf_conntrack_tcp_timeout_close - INTEGER (seconds)
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default 10
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nf_conntrack_tcp_timeout_close_wait - INTEGER (seconds)
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default 60
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nf_conntrack_tcp_timeout_established - INTEGER (seconds)
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default 432000 (5 days)
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nf_conntrack_tcp_timeout_fin_wait - INTEGER (seconds)
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default 120
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nf_conntrack_tcp_timeout_last_ack - INTEGER (seconds)
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default 30
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nf_conntrack_tcp_timeout_max_retrans - INTEGER (seconds)
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default 300
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nf_conntrack_tcp_timeout_syn_recv - INTEGER (seconds)
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default 60
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nf_conntrack_tcp_timeout_syn_sent - INTEGER (seconds)
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default 120
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nf_conntrack_tcp_timeout_time_wait - INTEGER (seconds)
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default 120
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nf_conntrack_tcp_timeout_unacknowledged - INTEGER (seconds)
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default 300
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nf_conntrack_timestamp - BOOLEAN
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0 - disabled (default)
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not 0 - enabled
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Enable connection tracking flow timestamping.
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nf_conntrack_udp_timeout - INTEGER (seconds)
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default 30
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nf_conntrack_udp_timeout_stream2 - INTEGER (seconds)
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default 180
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This extended timeout will be used in case there is an UDP stream
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detected.
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