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Documentation / networking / ipvs-sysctl.txt




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Based on kernel version 4.13.3. Page generated on 2017-09-23 13:55 EST.

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