Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1.. SPDX-License-Identifier: GPL-2.0
2
3===========
4IPvs-sysctl
5===========
6
7/proc/sys/net/ipv4/vs/* Variables:
8==================================
9
10am_droprate - INTEGER
11 default 10
12
13 It sets the always mode drop rate, which is used in the mode 3
14 of the drop_rate defense.
15
16amemthresh - INTEGER
17 default 1024
18
19 It sets the available memory threshold (in pages), which is
20 used in the automatic modes of defense. When there is no
21 enough available memory, the respective strategy will be
22 enabled and the variable is automatically set to 2, otherwise
23 the strategy is disabled and the variable is set to 1.
24
25backup_only - BOOLEAN
26 - 0 - disabled (default)
27 - not 0 - enabled
28
29 If set, disable the director function while the server is
30 in backup mode to avoid packet loops for DR/TUN methods.
31
32conn_reuse_mode - INTEGER
33 1 - default
34
35 Controls how ipvs will deal with connections that are detected
36 port reuse. It is a bitmap, with the values being:
37
38 0: disable any special handling on port reuse. The new
39 connection will be delivered to the same real server that was
40 servicing the previous connection.
41
42 bit 1: enable rescheduling of new connections when it is safe.
43 That is, whenever expire_nodest_conn and for TCP sockets, when
44 the connection is in TIME_WAIT state (which is only possible if
45 you use NAT mode).
46
47 bit 2: it is bit 1 plus, for TCP connections, when connections
48 are in FIN_WAIT state, as this is the last state seen by load
49 balancer in Direct Routing mode. This bit helps on adding new
50 real servers to a very busy cluster.
51
52conntrack - BOOLEAN
53 - 0 - disabled (default)
54 - not 0 - enabled
55
56 If set, maintain connection tracking entries for
57 connections handled by IPVS.
58
59 This should be enabled if connections handled by IPVS are to be
60 also handled by stateful firewall rules. That is, iptables rules
61 that make use of connection tracking. It is a performance
62 optimisation to disable this setting otherwise.
63
64 Connections handled by the IPVS FTP application module
65 will have connection tracking entries regardless of this setting.
66
67 Only available when IPVS is compiled with CONFIG_IP_VS_NFCT enabled.
68
69cache_bypass - BOOLEAN
70 - 0 - disabled (default)
71 - not 0 - enabled
72
73 If it is enabled, forward packets to the original destination
74 directly when no cache server is available and destination
75 address is not local (iph->daddr is RTN_UNICAST). It is mostly
76 used in transparent web cache cluster.
77
78debug_level - INTEGER
79 - 0 - transmission error messages (default)
80 - 1 - non-fatal error messages
81 - 2 - configuration
82 - 3 - destination trash
83 - 4 - drop entry
84 - 5 - service lookup
85 - 6 - scheduling
86 - 7 - connection new/expire, lookup and synchronization
87 - 8 - state transition
88 - 9 - binding destination, template checks and applications
89 - 10 - IPVS packet transmission
90 - 11 - IPVS packet handling (ip_vs_in/ip_vs_out)
91 - 12 or more - packet traversal
92
93 Only available when IPVS is compiled with CONFIG_IP_VS_DEBUG enabled.
94
95 Higher debugging levels include the messages for lower debugging
96 levels, so setting debug level 2, includes level 0, 1 and 2
97 messages. Thus, logging becomes more and more verbose the higher
98 the level.
99
100drop_entry - INTEGER
101 - 0 - disabled (default)
102
103 The drop_entry defense is to randomly drop entries in the
104 connection hash table, just in order to collect back some
105 memory for new connections. In the current code, the
106 drop_entry procedure can be activated every second, then it
107 randomly scans 1/32 of the whole and drops entries that are in
108 the SYN-RECV/SYNACK state, which should be effective against
109 syn-flooding attack.
110
111 The valid values of drop_entry are from 0 to 3, where 0 means
112 that this strategy is always disabled, 1 and 2 mean automatic
113 modes (when there is no enough available memory, the strategy
114 is enabled and the variable is automatically set to 2,
115 otherwise the strategy is disabled and the variable is set to
116 1), and 3 means that the strategy is always enabled.
117
118drop_packet - INTEGER
119 - 0 - disabled (default)
120
121 The drop_packet defense is designed to drop 1/rate packets
122 before forwarding them to real servers. If the rate is 1, then
123 drop all the incoming packets.
124
125 The value definition is the same as that of the drop_entry. In
126 the automatic mode, the rate is determined by the follow
127 formula: rate = amemthresh / (amemthresh - available_memory)
128 when available memory is less than the available memory
129 threshold. When the mode 3 is set, the always mode drop rate
130 is controlled by the /proc/sys/net/ipv4/vs/am_droprate.
131
132expire_nodest_conn - BOOLEAN
133 - 0 - disabled (default)
134 - not 0 - enabled
135
136 The default value is 0, the load balancer will silently drop
137 packets when its destination server is not available. It may
138 be useful, when user-space monitoring program deletes the
139 destination server (because of server overload or wrong
140 detection) and add back the server later, and the connections
141 to the server can continue.
142
143 If this feature is enabled, the load balancer will expire the
144 connection immediately when a packet arrives and its
145 destination server is not available, then the client program
146 will be notified that the connection is closed. This is
147 equivalent to the feature some people requires to flush
148 connections when its destination is not available.
149
150expire_quiescent_template - BOOLEAN
151 - 0 - disabled (default)
152 - not 0 - enabled
153
154 When set to a non-zero value, the load balancer will expire
155 persistent templates when the destination server is quiescent.
156 This may be useful, when a user makes a destination server
157 quiescent by setting its weight to 0 and it is desired that
158 subsequent otherwise persistent connections are sent to a
159 different destination server. By default new persistent
160 connections are allowed to quiescent destination servers.
161
162 If this feature is enabled, the load balancer will expire the
163 persistence template if it is to be used to schedule a new
164 connection and the destination server is quiescent.
165
166ignore_tunneled - BOOLEAN
167 - 0 - disabled (default)
168 - not 0 - enabled
169
170 If set, ipvs will set the ipvs_property on all packets which are of
171 unrecognized protocols. This prevents us from routing tunneled
172 protocols like ipip, which is useful to prevent rescheduling
173 packets that have been tunneled to the ipvs host (i.e. to prevent
174 ipvs routing loops when ipvs is also acting as a real server).
175
176nat_icmp_send - BOOLEAN
177 - 0 - disabled (default)
178 - not 0 - enabled
179
180 It controls sending icmp error messages (ICMP_DEST_UNREACH)
181 for VS/NAT when the load balancer receives packets from real
182 servers but the connection entries don't exist.
183
184pmtu_disc - BOOLEAN
185 - 0 - disabled
186 - not 0 - enabled (default)
187
188 By default, reject with FRAG_NEEDED all DF packets that exceed
189 the PMTU, irrespective of the forwarding method. For TUN method
190 the flag can be disabled to fragment such packets.
191
192secure_tcp - INTEGER
193 - 0 - disabled (default)
194
195 The secure_tcp defense is to use a more complicated TCP state
196 transition table. For VS/NAT, it also delays entering the
197 TCP ESTABLISHED state until the three way handshake is completed.
198
199 The value definition is the same as that of drop_entry and
200 drop_packet.
201
202sync_threshold - vector of 2 INTEGERs: sync_threshold, sync_period
203 default 3 50
204
205 It sets synchronization threshold, which is the minimum number
206 of incoming packets that a connection needs to receive before
207 the connection will be synchronized. A connection will be
208 synchronized, every time the number of its incoming packets
209 modulus sync_period equals the threshold. The range of the
210 threshold is from 0 to sync_period.
211
212 When sync_period and sync_refresh_period are 0, send sync only
213 for state changes or only once when pkts matches sync_threshold
214
215sync_refresh_period - UNSIGNED INTEGER
216 default 0
217
218 In seconds, difference in reported connection timer that triggers
219 new sync message. It can be used to avoid sync messages for the
220 specified period (or half of the connection timeout if it is lower)
221 if connection state is not changed since last sync.
222
223 This is useful for normal connections with high traffic to reduce
224 sync rate. Additionally, retry sync_retries times with period of
225 sync_refresh_period/8.
226
227sync_retries - INTEGER
228 default 0
229
230 Defines sync retries with period of sync_refresh_period/8. Useful
231 to protect against loss of sync messages. The range of the
232 sync_retries is from 0 to 3.
233
234sync_qlen_max - UNSIGNED LONG
235
236 Hard limit for queued sync messages that are not sent yet. It
237 defaults to 1/32 of the memory pages but actually represents
238 number of messages. It will protect us from allocating large
239 parts of memory when the sending rate is lower than the queuing
240 rate.
241
242sync_sock_size - INTEGER
243 default 0
244
245 Configuration of SNDBUF (master) or RCVBUF (slave) socket limit.
246 Default value is 0 (preserve system defaults).
247
248sync_ports - INTEGER
249 default 1
250
251 The number of threads that master and backup servers can use for
252 sync traffic. Every thread will use single UDP port, thread 0 will
253 use the default port 8848 while last thread will use port
254 8848+sync_ports-1.
255
256snat_reroute - BOOLEAN
257 - 0 - disabled
258 - not 0 - enabled (default)
259
260 If enabled, recalculate the route of SNATed packets from
261 realservers so that they are routed as if they originate from the
262 director. Otherwise they are routed as if they are forwarded by the
263 director.
264
265 If policy routing is in effect then it is possible that the route
266 of a packet originating from a director is routed differently to a
267 packet being forwarded by the director.
268
269 If policy routing is not in effect then the recalculated route will
270 always be the same as the original route so it is an optimisation
271 to disable snat_reroute and avoid the recalculation.
272
273sync_persist_mode - INTEGER
274 default 0
275
276 Controls the synchronisation of connections when using persistence
277
278 0: All types of connections are synchronised
279
280 1: Attempt to reduce the synchronisation traffic depending on
281 the connection type. For persistent services avoid synchronisation
282 for normal connections, do it only for persistence templates.
283 In such case, for TCP and SCTP it may need enabling sloppy_tcp and
284 sloppy_sctp flags on backup servers. For non-persistent services
285 such optimization is not applied, mode 0 is assumed.
286
287sync_version - INTEGER
288 default 1
289
290 The version of the synchronisation protocol used when sending
291 synchronisation messages.
292
293 0 selects the original synchronisation protocol (version 0). This
294 should be used when sending synchronisation messages to a legacy
295 system that only understands the original synchronisation protocol.
296
297 1 selects the current synchronisation protocol (version 1). This
298 should be used where possible.
299
300 Kernels with this sync_version entry are able to receive messages
301 of both version 1 and version 2 of the synchronisation protocol.
302
303run_estimation - BOOLEAN
304 0 - disabled
305 not 0 - enabled (default)
306
307 If disabled, the estimation will be stop, and you can't see
308 any update on speed estimation data.
309
310 You can always re-enable estimation by setting this value to 1.
311 But be careful, the first estimation after re-enable is not
312 accurate.