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Documentation / networking / ipvs-sysctl.txt




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Based on kernel version 3.2. Page generated on 2012-01-05 23:29 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	conntrack - BOOLEAN
19		0 - disabled (default)
20		not 0 - enabled
21	
22		If set, maintain connection tracking entries for
23		connections handled by IPVS.
24	
25		This should be enabled if connections handled by IPVS are to be
26		also handled by stateful firewall rules. That is, iptables rules
27		that make use of connection tracking.  It is a performance
28		optimisation to disable this setting otherwise.
29	
30		Connections handled by the IPVS FTP application module
31		will have connection tracking entries regardless of this setting.
32	
33		Only available when IPVS is compiled with CONFIG_IP_VS_NFCT enabled.
34	
35	cache_bypass - BOOLEAN
36	        0 - disabled (default)
37	        not 0 - enabled
38	
39	        If it is enabled, forward packets to the original destination
40	        directly when no cache server is available and destination
41	        address is not local (iph->daddr is RTN_UNICAST). It is mostly
42	        used in transparent web cache cluster.
43	
44	debug_level - INTEGER
45		0          - transmission error messages (default)
46		1          - non-fatal error messages
47		2          - configuration
48		3          - destination trash
49		4          - drop entry
50		5          - service lookup
51		6          - scheduling
52		7          - connection new/expire, lookup and synchronization
53		8          - state transition
54		9          - binding destination, template checks and applications
55		10         - IPVS packet transmission
56		11         - IPVS packet handling (ip_vs_in/ip_vs_out)
57		12 or more - packet traversal
58	
59		Only available when IPVS is compiled with CONFIG_IP_VS_DEBUG enabled.
60	
61		Higher debugging levels include the messages for lower debugging
62		levels, so setting debug level 2, includes level 0, 1 and 2
63		messages. Thus, logging becomes more and more verbose the higher
64		the level.
65	
66	drop_entry - INTEGER
67	        0  - disabled (default)
68	
69	        The drop_entry defense is to randomly drop entries in the
70	        connection hash table, just in order to collect back some
71	        memory for new connections. In the current code, the
72	        drop_entry procedure can be activated every second, then it
73	        randomly scans 1/32 of the whole and drops entries that are in
74	        the SYN-RECV/SYNACK state, which should be effective against
75	        syn-flooding attack.
76	
77	        The valid values of drop_entry are from 0 to 3, where 0 means
78	        that this strategy is always disabled, 1 and 2 mean automatic
79	        modes (when there is no enough available memory, the strategy
80	        is enabled and the variable is automatically set to 2,
81	        otherwise the strategy is disabled and the variable is set to
82	        1), and 3 means that that the strategy is always enabled.
83	
84	drop_packet - INTEGER
85	        0  - disabled (default)
86	
87	        The drop_packet defense is designed to drop 1/rate packets
88	        before forwarding them to real servers. If the rate is 1, then
89	        drop all the incoming packets.
90	
91	        The value definition is the same as that of the drop_entry. In
92	        the automatic mode, the rate is determined by the follow
93	        formula: rate = amemthresh / (amemthresh - available_memory)
94	        when available memory is less than the available memory
95	        threshold. When the mode 3 is set, the always mode drop rate
96	        is controlled by the /proc/sys/net/ipv4/vs/am_droprate.
97	
98	expire_nodest_conn - BOOLEAN
99	        0 - disabled (default)
100	        not 0 - enabled
101	
102	        The default value is 0, the load balancer will silently drop
103	        packets when its destination server is not available. It may
104	        be useful, when user-space monitoring program deletes the
105	        destination server (because of server overload or wrong
106	        detection) and add back the server later, and the connections
107	        to the server can continue.
108	
109	        If this feature is enabled, the load balancer will expire the
110	        connection immediately when a packet arrives and its
111	        destination server is not available, then the client program
112	        will be notified that the connection is closed. This is
113	        equivalent to the feature some people requires to flush
114	        connections when its destination is not available.
115	
116	expire_quiescent_template - BOOLEAN
117		0 - disabled (default)
118		not 0 - enabled
119	
120		When set to a non-zero value, the load balancer will expire
121		persistent templates when the destination server is quiescent.
122		This may be useful, when a user makes a destination server
123		quiescent by setting its weight to 0 and it is desired that
124		subsequent otherwise persistent connections are sent to a
125		different destination server.  By default new persistent
126		connections are allowed to quiescent destination servers.
127	
128		If this feature is enabled, the load balancer will expire the
129		persistence template if it is to be used to schedule a new
130		connection and the destination server is quiescent.
131	
132	nat_icmp_send - BOOLEAN
133	        0 - disabled (default)
134	        not 0 - enabled
135	
136	        It controls sending icmp error messages (ICMP_DEST_UNREACH)
137	        for VS/NAT when the load balancer receives packets from real
138	        servers but the connection entries don't exist.
139	
140	secure_tcp - INTEGER
141	        0  - disabled (default)
142	
143		The secure_tcp defense is to use a more complicated TCP state
144		transition table. For VS/NAT, it also delays entering the
145		TCP ESTABLISHED state until the three way handshake is completed.
146	
147	        The value definition is the same as that of drop_entry and
148	        drop_packet.
149	
150	sync_threshold - INTEGER
151	        default 3
152	
153	        It sets synchronization threshold, which is the minimum number
154	        of incoming packets that a connection needs to receive before
155	        the connection will be synchronized. A connection will be
156	        synchronized, every time the number of its incoming packets
157	        modulus 50 equals the threshold. The range of the threshold is
158	        from 0 to 49.
159	
160	snat_reroute - BOOLEAN
161		0 - disabled
162		not 0 - enabled (default)
163	
164		If enabled, recalculate the route of SNATed packets from
165		realservers so that they are routed as if they originate from the
166		director. Otherwise they are routed as if they are forwarded by the
167		director.
168	
169		If policy routing is in effect then it is possible that the route
170		of a packet originating from a director is routed differently to a
171		packet being forwarded by the director.
172	
173		If policy routing is not in effect then the recalculated route will
174		always be the same as the original route so it is an optimisation
175		to disable snat_reroute and avoid the recalculation.
176	
177	sync_version - INTEGER
178		default 1
179	
180		The version of the synchronisation protocol used when sending
181		synchronisation messages.
182	
183		0 selects the original synchronisation protocol (version 0). This
184		should be used when sending synchronisation messages to a legacy
185		system that only understands the original synchronisation protocol.
186	
187		1 selects the current synchronisation protocol (version 1). This
188		should be used where possible.
189	
190		Kernels with this sync_version entry are able to receive messages
191		of both version 1 and version 2 of the synchronisation protocol.
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