1.. SPDX-License-Identifier: GPL-2.0
  2
  3===================================
  4Netfilter Conntrack Sysfs variables
  5===================================
  6
  7/proc/sys/net/netfilter/nf_conntrack_* Variables:
  8=================================================
  9
 10nf_conntrack_acct - BOOLEAN
 11	- 0 - disabled (default)
 12	- not 0 - enabled
 13
 14	Enable connection tracking flow accounting. 64-bit byte and packet
 15	counters per flow are added.
 16
 17nf_conntrack_buckets - INTEGER
 18	Size of hash table. If not specified as parameter during module
 19	loading, the default size is calculated by dividing total memory
 20	by 16384 to determine the number of buckets. The hash table will
 21	never have fewer than 1024 and never more than 262144 buckets.
 22	This sysctl is only writeable in the initial net namespace.
 23
 24nf_conntrack_checksum - BOOLEAN
 25	- 0 - disabled
 26	- not 0 - enabled (default)
 27
 28	Verify checksum of incoming packets. Packets with bad checksums are
 29	in INVALID state. If this is enabled, such packets will not be
 30	considered for connection tracking.
 31
 32nf_conntrack_count - INTEGER (read-only)
 33	Number of currently allocated flow entries.
 34
 35nf_conntrack_events - BOOLEAN
 36	- 0 - disabled
 37	- 1 - enabled
 38	- 2 - auto (default)
 39
 40	If this option is enabled, the connection tracking code will
 41	provide userspace with connection tracking events via ctnetlink.
 42	The default allocates the extension if a userspace program is
 43	listening to ctnetlink events.
 44
 45nf_conntrack_expect_max - INTEGER
 46	Maximum size of expectation table.  Default value is
 47	nf_conntrack_buckets / 256. Minimum is 1.
 48
 49nf_conntrack_frag6_high_thresh - INTEGER
 50	default 262144
 51
 52	Maximum memory used to reassemble IPv6 fragments.  When
 53	nf_conntrack_frag6_high_thresh bytes of memory is allocated for this
 54	purpose, the fragment handler will toss packets until
 55	nf_conntrack_frag6_low_thresh is reached.
 56
 57nf_conntrack_frag6_low_thresh - INTEGER
 58	default 196608
 59
 60	See nf_conntrack_frag6_low_thresh
 61
 62nf_conntrack_frag6_timeout - INTEGER (seconds)
 63	default 60
 64
 65	Time to keep an IPv6 fragment in memory.
 66
 67nf_conntrack_generic_timeout - INTEGER (seconds)
 68	default 600
 69
 70	Default for generic timeout.  This refers to layer 4 unknown/unsupported
 71	protocols.
 72
 73nf_conntrack_icmp_timeout - INTEGER (seconds)
 74	default 30
 75
 76	Default for ICMP timeout.
 77
 78nf_conntrack_icmpv6_timeout - INTEGER (seconds)
 79	default 30
 80
 81	Default for ICMP6 timeout.
 82
 83nf_conntrack_log_invalid - INTEGER
 84	- 0   - disable (default)
 85	- 1   - log ICMP packets
 86	- 6   - log TCP packets
 87	- 17  - log UDP packets
 88	- 33  - log DCCP packets
 89	- 41  - log ICMPv6 packets
 90	- 136 - log UDPLITE packets
 91	- 255 - log packets of any protocol
 92
 93	Log invalid packets of a type specified by value.
 94
 95nf_conntrack_max - INTEGER
 96        Maximum number of allowed connection tracking entries. This value is set
 97        to nf_conntrack_buckets by default.
 98        Note that connection tracking entries are added to the table twice -- once
 99        for the original direction and once for the reply direction (i.e., with
100        the reversed address). This means that with default settings a maxed-out
101        table will have a average hash chain length of 2, not 1.
102
103nf_conntrack_tcp_be_liberal - BOOLEAN
104	- 0 - disabled (default)
105	- not 0 - enabled
106
107	Be conservative in what you do, be liberal in what you accept from others.
108	If it's non-zero, we mark only out of window RST segments as INVALID.
109
110nf_conntrack_tcp_ignore_invalid_rst - BOOLEAN
111	- 0 - disabled (default)
112	- 1 - enabled
113
114	If it's 1, we don't mark out of window RST segments as INVALID.
115
116nf_conntrack_tcp_loose - BOOLEAN
117	- 0 - disabled
118	- not 0 - enabled (default)
119
120	If it is set to zero, we disable picking up already established
121	connections.
122
123nf_conntrack_tcp_max_retrans - INTEGER
124	default 3
125
126	Maximum number of packets that can be retransmitted without
127	received an (acceptable) ACK from the destination. If this number
128	is reached, a shorter timer will be started.
129
130nf_conntrack_tcp_timeout_close - INTEGER (seconds)
131	default 10
132
133nf_conntrack_tcp_timeout_close_wait - INTEGER (seconds)
134	default 60
135
136nf_conntrack_tcp_timeout_established - INTEGER (seconds)
137	default 432000 (5 days)
138
139nf_conntrack_tcp_timeout_fin_wait - INTEGER (seconds)
140	default 120
141
142nf_conntrack_tcp_timeout_last_ack - INTEGER (seconds)
143	default 30
144
145nf_conntrack_tcp_timeout_max_retrans - INTEGER (seconds)
146	default 300
147
148nf_conntrack_tcp_timeout_syn_recv - INTEGER (seconds)
149	default 60
150
151nf_conntrack_tcp_timeout_syn_sent - INTEGER (seconds)
152	default 120
153
154nf_conntrack_tcp_timeout_time_wait - INTEGER (seconds)
155	default 120
156
157nf_conntrack_tcp_timeout_unacknowledged - INTEGER (seconds)
158	default 300
159
160nf_conntrack_timestamp - BOOLEAN
161	- 0 - disabled (default)
162	- not 0 - enabled
163
164	Enable connection tracking flow timestamping.
165
166nf_conntrack_sctp_timeout_closed - INTEGER (seconds)
167	default 10
168
169nf_conntrack_sctp_timeout_cookie_wait - INTEGER (seconds)
170	default 3
171
172nf_conntrack_sctp_timeout_cookie_echoed - INTEGER (seconds)
173	default 3
174
175nf_conntrack_sctp_timeout_established - INTEGER (seconds)
176	default 210
177
178	Default is set to (hb_interval * path_max_retrans + rto_max)
179
180nf_conntrack_sctp_timeout_shutdown_sent - INTEGER (seconds)
181	default 3
182
183nf_conntrack_sctp_timeout_shutdown_recd - INTEGER (seconds)
184	default 3
185
186nf_conntrack_sctp_timeout_shutdown_ack_sent - INTEGER (seconds)
187	default 3
188
189nf_conntrack_sctp_timeout_heartbeat_sent - INTEGER (seconds)
190	default 30
191
192	This timeout is used to setup conntrack entry on secondary paths.
193	Default is set to hb_interval.
194
195nf_conntrack_udp_timeout - INTEGER (seconds)
196	default 30
197
198nf_conntrack_udp_timeout_stream - INTEGER (seconds)
199	default 120
200
201	This extended timeout will be used in case there is an UDP stream
202	detected.
203
204nf_conntrack_gre_timeout - INTEGER (seconds)
205	default 30
206
207nf_conntrack_gre_timeout_stream - INTEGER (seconds)
208	default 180
209
210	This extended timeout will be used in case there is an GRE stream
211	detected.
212
213nf_hooks_lwtunnel - BOOLEAN
214	- 0 - disabled (default)
215	- not 0 - enabled
216
217	If this option is enabled, the lightweight tunnel netfilter hooks are
218	enabled. This option cannot be disabled once it is enabled.
219
220nf_flowtable_tcp_timeout - INTEGER (seconds)
221        default 30
222
223        Control offload timeout for tcp connections.
224        TCP connections may be offloaded from nf conntrack to nf flow table.
225        Once aged, the connection is returned to nf conntrack.
226
227nf_flowtable_udp_timeout - INTEGER (seconds)
228        default 30
229
230        Control offload timeout for udp connections.
231        UDP connections may be offloaded from nf conntrack to nf flow table.
232        Once aged, the connection is returned to nf conntrack.