About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / networking / ipvs-sysctl.txt




Custom Search

Based on kernel version 4.1. Page generated on 2015-06-28 12:13 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	nat_icmp_send - BOOLEAN
161	        0 - disabled (default)
162	        not 0 - enabled
163	
164	        It controls sending icmp error messages (ICMP_DEST_UNREACH)
165	        for VS/NAT when the load balancer receives packets from real
166	        servers but the connection entries don't exist.
167	
168	secure_tcp - INTEGER
169	        0  - disabled (default)
170	
171		The secure_tcp defense is to use a more complicated TCP state
172		transition table. For VS/NAT, it also delays entering the
173		TCP ESTABLISHED state until the three way handshake is completed.
174	
175	        The value definition is the same as that of drop_entry and
176	        drop_packet.
177	
178	sync_threshold - INTEGER
179	        default 3
180	
181	        It sets synchronization threshold, which is the minimum number
182	        of incoming packets that a connection needs to receive before
183	        the connection will be synchronized. A connection will be
184	        synchronized, every time the number of its incoming packets
185	        modulus 50 equals the threshold. The range of the threshold is
186	        from 0 to 49.
187	
188	snat_reroute - BOOLEAN
189		0 - disabled
190		not 0 - enabled (default)
191	
192		If enabled, recalculate the route of SNATed packets from
193		realservers so that they are routed as if they originate from the
194		director. Otherwise they are routed as if they are forwarded by the
195		director.
196	
197		If policy routing is in effect then it is possible that the route
198		of a packet originating from a director is routed differently to a
199		packet being forwarded by the director.
200	
201		If policy routing is not in effect then the recalculated route will
202		always be the same as the original route so it is an optimisation
203		to disable snat_reroute and avoid the recalculation.
204	
205	sync_persist_mode - INTEGER
206		default 0
207	
208		Controls the synchronisation of connections when using persistence
209	
210		0: All types of connections are synchronised
211		1: Attempt to reduce the synchronisation traffic depending on
212		the connection type. For persistent services avoid synchronisation
213		for normal connections, do it only for persistence templates.
214		In such case, for TCP and SCTP it may need enabling sloppy_tcp and
215		sloppy_sctp flags on backup servers. For non-persistent services
216		such optimization is not applied, mode 0 is assumed.
217	
218	sync_version - INTEGER
219		default 1
220	
221		The version of the synchronisation protocol used when sending
222		synchronisation messages.
223	
224		0 selects the original synchronisation protocol (version 0). This
225		should be used when sending synchronisation messages to a legacy
226		system that only understands the original synchronisation protocol.
227	
228		1 selects the current synchronisation protocol (version 1). This
229		should be used where possible.
230	
231		Kernels with this sync_version entry are able to receive messages
232		of both version 1 and version 2 of the synchronisation protocol.
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.