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Documentation / networking / ipvs-sysctl.txt




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Based on kernel version 3.13. Page generated on 2014-01-20 22:03 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	conntrack - BOOLEAN
26		0 - disabled (default)
27		not 0 - enabled
28	
29		If set, maintain connection tracking entries for
30		connections handled by IPVS.
31	
32		This should be enabled if connections handled by IPVS are to be
33		also handled by stateful firewall rules. That is, iptables rules
34		that make use of connection tracking.  It is a performance
35		optimisation to disable this setting otherwise.
36	
37		Connections handled by the IPVS FTP application module
38		will have connection tracking entries regardless of this setting.
39	
40		Only available when IPVS is compiled with CONFIG_IP_VS_NFCT enabled.
41	
42	cache_bypass - BOOLEAN
43	        0 - disabled (default)
44	        not 0 - enabled
45	
46	        If it is enabled, forward packets to the original destination
47	        directly when no cache server is available and destination
48	        address is not local (iph->daddr is RTN_UNICAST). It is mostly
49	        used in transparent web cache cluster.
50	
51	debug_level - INTEGER
52		0          - transmission error messages (default)
53		1          - non-fatal error messages
54		2          - configuration
55		3          - destination trash
56		4          - drop entry
57		5          - service lookup
58		6          - scheduling
59		7          - connection new/expire, lookup and synchronization
60		8          - state transition
61		9          - binding destination, template checks and applications
62		10         - IPVS packet transmission
63		11         - IPVS packet handling (ip_vs_in/ip_vs_out)
64		12 or more - packet traversal
65	
66		Only available when IPVS is compiled with CONFIG_IP_VS_DEBUG enabled.
67	
68		Higher debugging levels include the messages for lower debugging
69		levels, so setting debug level 2, includes level 0, 1 and 2
70		messages. Thus, logging becomes more and more verbose the higher
71		the level.
72	
73	drop_entry - INTEGER
74	        0  - disabled (default)
75	
76	        The drop_entry defense is to randomly drop entries in the
77	        connection hash table, just in order to collect back some
78	        memory for new connections. In the current code, the
79	        drop_entry procedure can be activated every second, then it
80	        randomly scans 1/32 of the whole and drops entries that are in
81	        the SYN-RECV/SYNACK state, which should be effective against
82	        syn-flooding attack.
83	
84	        The valid values of drop_entry are from 0 to 3, where 0 means
85	        that this strategy is always disabled, 1 and 2 mean automatic
86	        modes (when there is no enough available memory, the strategy
87	        is enabled and the variable is automatically set to 2,
88	        otherwise the strategy is disabled and the variable is set to
89	        1), and 3 means that that the strategy is always enabled.
90	
91	drop_packet - INTEGER
92	        0  - disabled (default)
93	
94	        The drop_packet defense is designed to drop 1/rate packets
95	        before forwarding them to real servers. If the rate is 1, then
96	        drop all the incoming packets.
97	
98	        The value definition is the same as that of the drop_entry. In
99	        the automatic mode, the rate is determined by the follow
100	        formula: rate = amemthresh / (amemthresh - available_memory)
101	        when available memory is less than the available memory
102	        threshold. When the mode 3 is set, the always mode drop rate
103	        is controlled by the /proc/sys/net/ipv4/vs/am_droprate.
104	
105	expire_nodest_conn - BOOLEAN
106	        0 - disabled (default)
107	        not 0 - enabled
108	
109	        The default value is 0, the load balancer will silently drop
110	        packets when its destination server is not available. It may
111	        be useful, when user-space monitoring program deletes the
112	        destination server (because of server overload or wrong
113	        detection) and add back the server later, and the connections
114	        to the server can continue.
115	
116	        If this feature is enabled, the load balancer will expire the
117	        connection immediately when a packet arrives and its
118	        destination server is not available, then the client program
119	        will be notified that the connection is closed. This is
120	        equivalent to the feature some people requires to flush
121	        connections when its destination is not available.
122	
123	expire_quiescent_template - BOOLEAN
124		0 - disabled (default)
125		not 0 - enabled
126	
127		When set to a non-zero value, the load balancer will expire
128		persistent templates when the destination server is quiescent.
129		This may be useful, when a user makes a destination server
130		quiescent by setting its weight to 0 and it is desired that
131		subsequent otherwise persistent connections are sent to a
132		different destination server.  By default new persistent
133		connections are allowed to quiescent destination servers.
134	
135		If this feature is enabled, the load balancer will expire the
136		persistence template if it is to be used to schedule a new
137		connection and the destination server is quiescent.
138	
139	nat_icmp_send - BOOLEAN
140	        0 - disabled (default)
141	        not 0 - enabled
142	
143	        It controls sending icmp error messages (ICMP_DEST_UNREACH)
144	        for VS/NAT when the load balancer receives packets from real
145	        servers but the connection entries don't exist.
146	
147	secure_tcp - INTEGER
148	        0  - disabled (default)
149	
150		The secure_tcp defense is to use a more complicated TCP state
151		transition table. For VS/NAT, it also delays entering the
152		TCP ESTABLISHED state until the three way handshake is completed.
153	
154	        The value definition is the same as that of drop_entry and
155	        drop_packet.
156	
157	sync_threshold - INTEGER
158	        default 3
159	
160	        It sets synchronization threshold, which is the minimum number
161	        of incoming packets that a connection needs to receive before
162	        the connection will be synchronized. A connection will be
163	        synchronized, every time the number of its incoming packets
164	        modulus 50 equals the threshold. The range of the threshold is
165	        from 0 to 49.
166	
167	snat_reroute - BOOLEAN
168		0 - disabled
169		not 0 - enabled (default)
170	
171		If enabled, recalculate the route of SNATed packets from
172		realservers so that they are routed as if they originate from the
173		director. Otherwise they are routed as if they are forwarded by the
174		director.
175	
176		If policy routing is in effect then it is possible that the route
177		of a packet originating from a director is routed differently to a
178		packet being forwarded by the director.
179	
180		If policy routing is not in effect then the recalculated route will
181		always be the same as the original route so it is an optimisation
182		to disable snat_reroute and avoid the recalculation.
183	
184	sync_persist_mode - INTEGER
185		default 0
186	
187		Controls the synchronisation of connections when using persistence
188	
189		0: All types of connections are synchronised
190		1: Attempt to reduce the synchronisation traffic depending on
191		the connection type. For persistent services avoid synchronisation
192		for normal connections, do it only for persistence templates.
193		In such case, for TCP and SCTP it may need enabling sloppy_tcp and
194		sloppy_sctp flags on backup servers. For non-persistent services
195		such optimization is not applied, mode 0 is assumed.
196	
197	sync_version - INTEGER
198		default 1
199	
200		The version of the synchronisation protocol used when sending
201		synchronisation messages.
202	
203		0 selects the original synchronisation protocol (version 0). This
204		should be used when sending synchronisation messages to a legacy
205		system that only understands the original synchronisation protocol.
206	
207		1 selects the current synchronisation protocol (version 1). This
208		should be used where possible.
209	
210		Kernels with this sync_version entry are able to receive messages
211		of both version 1 and version 2 of the synchronisation protocol.
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