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 but the hash table will 21 never have fewer than 32 and limited to 16384 buckets. For systems 22 with more than 4GB of memory it will be 65536 buckets. 23 This sysctl is only writeable in the initial net namespace. 24 25nf_conntrack_checksum - BOOLEAN 26 - 0 - disabled 27 - not 0 - enabled (default) 28 29 Verify checksum of incoming packets. Packets with bad checksums are 30 in INVALID state. If this is enabled, such packets will not be 31 considered for connection tracking. 32 33nf_conntrack_count - INTEGER (read-only) 34 Number of currently allocated flow entries. 35 36nf_conntrack_events - BOOLEAN 37 - 0 - disabled 38 - not 0 - enabled (default) 39 40 If this option is enabled, the connection tracking code will 41 provide userspace with connection tracking events via ctnetlink. 42 43nf_conntrack_expect_max - INTEGER 44 Maximum size of expectation table. Default value is 45 nf_conntrack_buckets / 256. Minimum is 1. 46 47nf_conntrack_frag6_high_thresh - INTEGER 48 default 262144 49 50 Maximum memory used to reassemble IPv6 fragments. When 51 nf_conntrack_frag6_high_thresh bytes of memory is allocated for this 52 purpose, the fragment handler will toss packets until 53 nf_conntrack_frag6_low_thresh is reached. 54 55nf_conntrack_frag6_low_thresh - INTEGER 56 default 196608 57 58 See nf_conntrack_frag6_low_thresh 59 60nf_conntrack_frag6_timeout - INTEGER (seconds) 61 default 60 62 63 Time to keep an IPv6 fragment in memory. 64 65nf_conntrack_generic_timeout - INTEGER (seconds) 66 default 600 67 68 Default for generic timeout. This refers to layer 4 unknown/unsupported 69 protocols. 70 71nf_conntrack_helper - BOOLEAN 72 - 0 - disabled (default) 73 - not 0 - enabled 74 75 Enable automatic conntrack helper assignment. 76 If disabled it is required to set up iptables rules to assign 77 helpers to connections. See the CT target description in the 78 iptables-extensions(8) man page for further information. 79 80nf_conntrack_icmp_timeout - INTEGER (seconds) 81 default 30 82 83 Default for ICMP timeout. 84 85nf_conntrack_icmpv6_timeout - INTEGER (seconds) 86 default 30 87 88 Default for ICMP6 timeout. 89 90nf_conntrack_log_invalid - INTEGER 91 - 0 - disable (default) 92 - 1 - log ICMP packets 93 - 6 - log TCP packets 94 - 17 - log UDP packets 95 - 33 - log DCCP packets 96 - 41 - log ICMPv6 packets 97 - 136 - log UDPLITE packets 98 - 255 - log packets of any protocol 99 100 Log invalid packets of a type specified by value. 101 102nf_conntrack_max - INTEGER 103 Size of connection tracking table. Default value is 104 nf_conntrack_buckets value * 4. 105 106nf_conntrack_tcp_be_liberal - BOOLEAN 107 - 0 - disabled (default) 108 - not 0 - enabled 109 110 Be conservative in what you do, be liberal in what you accept from others. 111 If it's non-zero, we mark only out of window RST segments as INVALID. 112 113nf_conntrack_tcp_ignore_invalid_rst - BOOLEAN 114 - 0 - disabled (default) 115 - 1 - enabled 116 117 If it's 1, we don't mark out of window RST segments as INVALID. 118 119nf_conntrack_tcp_loose - BOOLEAN 120 - 0 - disabled 121 - not 0 - enabled (default) 122 123 If it is set to zero, we disable picking up already established 124 connections. 125 126nf_conntrack_tcp_max_retrans - INTEGER 127 default 3 128 129 Maximum number of packets that can be retransmitted without 130 received an (acceptable) ACK from the destination. If this number 131 is reached, a shorter timer will be started. 132 133nf_conntrack_tcp_timeout_close - INTEGER (seconds) 134 default 10 135 136nf_conntrack_tcp_timeout_close_wait - INTEGER (seconds) 137 default 60 138 139nf_conntrack_tcp_timeout_established - INTEGER (seconds) 140 default 432000 (5 days) 141 142nf_conntrack_tcp_timeout_fin_wait - INTEGER (seconds) 143 default 120 144 145nf_conntrack_tcp_timeout_last_ack - INTEGER (seconds) 146 default 30 147 148nf_conntrack_tcp_timeout_max_retrans - INTEGER (seconds) 149 default 300 150 151nf_conntrack_tcp_timeout_syn_recv - INTEGER (seconds) 152 default 60 153 154nf_conntrack_tcp_timeout_syn_sent - INTEGER (seconds) 155 default 120 156 157nf_conntrack_tcp_timeout_time_wait - INTEGER (seconds) 158 default 120 159 160nf_conntrack_tcp_timeout_unacknowledged - INTEGER (seconds) 161 default 300 162 163nf_conntrack_timestamp - BOOLEAN 164 - 0 - disabled (default) 165 - not 0 - enabled 166 167 Enable connection tracking flow timestamping. 168 169nf_conntrack_udp_timeout - INTEGER (seconds) 170 default 30 171 172nf_conntrack_udp_timeout_stream - INTEGER (seconds) 173 default 120 174 175 This extended timeout will be used in case there is an UDP stream 176 detected. 177 178nf_conntrack_gre_timeout - INTEGER (seconds) 179 default 30 180 181nf_conntrack_gre_timeout_stream - INTEGER (seconds) 182 default 180 183 184 This extended timeout will be used in case there is an GRE stream 185 detected. 186 187nf_flowtable_tcp_timeout - INTEGER (seconds) 188 default 30 189 190 Control offload timeout for tcp connections. 191 TCP connections may be offloaded from nf conntrack to nf flow table. 192 Once aged, the connection is returned to nf conntrack with tcp pickup timeout. 193 194nf_flowtable_tcp_pickup - INTEGER (seconds) 195 default 120 196 197 TCP connection timeout after being aged from nf flow table offload. 198 199nf_flowtable_udp_timeout - INTEGER (seconds) 200 default 30 201 202 Control offload timeout for udp connections. 203 UDP connections may be offloaded from nf conntrack to nf flow table. 204 Once aged, the connection is returned to nf conntrack with udp pickup timeout. 205 206nf_flowtable_udp_pickup - INTEGER (seconds) 207 default 30 208 209 UDP connection timeout after being aged from nf flow table offload. 210