nf_conntrack-sysctl.rst (6214B)
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_helper - BOOLEAN 74 - 0 - disabled (default) 75 - not 0 - enabled 76 77 Enable automatic conntrack helper assignment. 78 If disabled it is required to set up iptables rules to assign 79 helpers to connections. See the CT target description in the 80 iptables-extensions(8) man page for further information. 81 82nf_conntrack_icmp_timeout - INTEGER (seconds) 83 default 30 84 85 Default for ICMP timeout. 86 87nf_conntrack_icmpv6_timeout - INTEGER (seconds) 88 default 30 89 90 Default for ICMP6 timeout. 91 92nf_conntrack_log_invalid - INTEGER 93 - 0 - disable (default) 94 - 1 - log ICMP packets 95 - 6 - log TCP packets 96 - 17 - log UDP packets 97 - 33 - log DCCP packets 98 - 41 - log ICMPv6 packets 99 - 136 - log UDPLITE packets 100 - 255 - log packets of any protocol 101 102 Log invalid packets of a type specified by value. 103 104nf_conntrack_max - INTEGER 105 Maximum number of allowed connection tracking entries. This value is set 106 to nf_conntrack_buckets by default. 107 Note that connection tracking entries are added to the table twice -- once 108 for the original direction and once for the reply direction (i.e., with 109 the reversed address). This means that with default settings a maxed-out 110 table will have a average hash chain length of 2, not 1. 111 112nf_conntrack_tcp_be_liberal - BOOLEAN 113 - 0 - disabled (default) 114 - not 0 - enabled 115 116 Be conservative in what you do, be liberal in what you accept from others. 117 If it's non-zero, we mark only out of window RST segments as INVALID. 118 119nf_conntrack_tcp_ignore_invalid_rst - BOOLEAN 120 - 0 - disabled (default) 121 - 1 - enabled 122 123 If it's 1, we don't mark out of window RST segments as INVALID. 124 125nf_conntrack_tcp_loose - BOOLEAN 126 - 0 - disabled 127 - not 0 - enabled (default) 128 129 If it is set to zero, we disable picking up already established 130 connections. 131 132nf_conntrack_tcp_max_retrans - INTEGER 133 default 3 134 135 Maximum number of packets that can be retransmitted without 136 received an (acceptable) ACK from the destination. If this number 137 is reached, a shorter timer will be started. 138 139nf_conntrack_tcp_timeout_close - INTEGER (seconds) 140 default 10 141 142nf_conntrack_tcp_timeout_close_wait - INTEGER (seconds) 143 default 60 144 145nf_conntrack_tcp_timeout_established - INTEGER (seconds) 146 default 432000 (5 days) 147 148nf_conntrack_tcp_timeout_fin_wait - INTEGER (seconds) 149 default 120 150 151nf_conntrack_tcp_timeout_last_ack - INTEGER (seconds) 152 default 30 153 154nf_conntrack_tcp_timeout_max_retrans - INTEGER (seconds) 155 default 300 156 157nf_conntrack_tcp_timeout_syn_recv - INTEGER (seconds) 158 default 60 159 160nf_conntrack_tcp_timeout_syn_sent - INTEGER (seconds) 161 default 120 162 163nf_conntrack_tcp_timeout_time_wait - INTEGER (seconds) 164 default 120 165 166nf_conntrack_tcp_timeout_unacknowledged - INTEGER (seconds) 167 default 300 168 169nf_conntrack_timestamp - BOOLEAN 170 - 0 - disabled (default) 171 - not 0 - enabled 172 173 Enable connection tracking flow timestamping. 174 175nf_conntrack_udp_timeout - INTEGER (seconds) 176 default 30 177 178nf_conntrack_udp_timeout_stream - INTEGER (seconds) 179 default 120 180 181 This extended timeout will be used in case there is an UDP stream 182 detected. 183 184nf_conntrack_gre_timeout - INTEGER (seconds) 185 default 30 186 187nf_conntrack_gre_timeout_stream - INTEGER (seconds) 188 default 180 189 190 This extended timeout will be used in case there is an GRE stream 191 detected. 192 193nf_hooks_lwtunnel - BOOLEAN 194 - 0 - disabled (default) 195 - not 0 - enabled 196 197 If this option is enabled, the lightweight tunnel netfilter hooks are 198 enabled. This option cannot be disabled once it is enabled. 199 200nf_flowtable_tcp_timeout - INTEGER (seconds) 201 default 30 202 203 Control offload timeout for tcp connections. 204 TCP connections may be offloaded from nf conntrack to nf flow table. 205 Once aged, the connection is returned to nf conntrack with tcp pickup timeout. 206 207nf_flowtable_udp_timeout - INTEGER (seconds) 208 default 30 209 210 Control offload timeout for udp connections. 211 UDP connections may be offloaded from nf conntrack to nf flow table. 212 Once aged, the connection is returned to nf conntrack with udp pickup timeout.