diff options
Diffstat (limited to 'Documentation/networking/ipvs-sysctl.txt')
| -rw-r--r-- | Documentation/networking/ipvs-sysctl.txt | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/Documentation/networking/ipvs-sysctl.txt b/Documentation/networking/ipvs-sysctl.txt new file mode 100644 index 000000000..3ba709531 --- /dev/null +++ b/Documentation/networking/ipvs-sysctl.txt @@ -0,0 +1,232 @@ +/proc/sys/net/ipv4/vs/* Variables: + +am_droprate - INTEGER + default 10 + + It sets the always mode drop rate, which is used in the mode 3 + of the drop_rate defense. + +amemthresh - INTEGER + default 1024 + + It sets the available memory threshold (in pages), which is + used in the automatic modes of defense. When there is no + enough available memory, the respective strategy will be + enabled and the variable is automatically set to 2, otherwise + the strategy is disabled and the variable is set to 1. + +backup_only - BOOLEAN + 0 - disabled (default) + not 0 - enabled + + If set, disable the director function while the server is + in backup mode to avoid packet loops for DR/TUN methods. + +conn_reuse_mode - INTEGER + 1 - default + + Controls how ipvs will deal with connections that are detected + port reuse. It is a bitmap, with the values being: + + 0: disable any special handling on port reuse. The new + connection will be delivered to the same real server that was + servicing the previous connection. This will effectively + disable expire_nodest_conn. + + bit 1: enable rescheduling of new connections when it is safe. + That is, whenever expire_nodest_conn and for TCP sockets, when + the connection is in TIME_WAIT state (which is only possible if + you use NAT mode). + + bit 2: it is bit 1 plus, for TCP connections, when connections + are in FIN_WAIT state, as this is the last state seen by load + balancer in Direct Routing mode. This bit helps on adding new + real servers to a very busy cluster. + +conntrack - BOOLEAN + 0 - disabled (default) + not 0 - enabled + + If set, maintain connection tracking entries for + connections handled by IPVS. + + This should be enabled if connections handled by IPVS are to be + also handled by stateful firewall rules. That is, iptables rules + that make use of connection tracking. It is a performance + optimisation to disable this setting otherwise. + + Connections handled by the IPVS FTP application module + will have connection tracking entries regardless of this setting. + + Only available when IPVS is compiled with CONFIG_IP_VS_NFCT enabled. + +cache_bypass - BOOLEAN + 0 - disabled (default) + not 0 - enabled + + If it is enabled, forward packets to the original destination + directly when no cache server is available and destination + address is not local (iph->daddr is RTN_UNICAST). It is mostly + used in transparent web cache cluster. + +debug_level - INTEGER + 0 - transmission error messages (default) + 1 - non-fatal error messages + 2 - configuration + 3 - destination trash + 4 - drop entry + 5 - service lookup + 6 - scheduling + 7 - connection new/expire, lookup and synchronization + 8 - state transition + 9 - binding destination, template checks and applications + 10 - IPVS packet transmission + 11 - IPVS packet handling (ip_vs_in/ip_vs_out) + 12 or more - packet traversal + + Only available when IPVS is compiled with CONFIG_IP_VS_DEBUG enabled. + + Higher debugging levels include the messages for lower debugging + levels, so setting debug level 2, includes level 0, 1 and 2 + messages. Thus, logging becomes more and more verbose the higher + the level. + +drop_entry - INTEGER + 0 - disabled (default) + + The drop_entry defense is to randomly drop entries in the + connection hash table, just in order to collect back some + memory for new connections. In the current code, the + drop_entry procedure can be activated every second, then it + randomly scans 1/32 of the whole and drops entries that are in + the SYN-RECV/SYNACK state, which should be effective against + syn-flooding attack. + + The valid values of drop_entry are from 0 to 3, where 0 means + that this strategy is always disabled, 1 and 2 mean automatic + modes (when there is no enough available memory, the strategy + is enabled and the variable is automatically set to 2, + otherwise the strategy is disabled and the variable is set to + 1), and 3 means that that the strategy is always enabled. + +drop_packet - INTEGER + 0 - disabled (default) + + The drop_packet defense is designed to drop 1/rate packets + before forwarding them to real servers. If the rate is 1, then + drop all the incoming packets. + + The value definition is the same as that of the drop_entry. In + the automatic mode, the rate is determined by the follow + formula: rate = amemthresh / (amemthresh - available_memory) + when available memory is less than the available memory + threshold. When the mode 3 is set, the always mode drop rate + is controlled by the /proc/sys/net/ipv4/vs/am_droprate. + +expire_nodest_conn - BOOLEAN + 0 - disabled (default) + not 0 - enabled + + The default value is 0, the load balancer will silently drop + packets when its destination server is not available. It may + be useful, when user-space monitoring program deletes the + destination server (because of server overload or wrong + detection) and add back the server later, and the connections + to the server can continue. + + If this feature is enabled, the load balancer will expire the + connection immediately when a packet arrives and its + destination server is not available, then the client program + will be notified that the connection is closed. This is + equivalent to the feature some people requires to flush + connections when its destination is not available. + +expire_quiescent_template - BOOLEAN + 0 - disabled (default) + not 0 - enabled + + When set to a non-zero value, the load balancer will expire + persistent templates when the destination server is quiescent. + This may be useful, when a user makes a destination server + quiescent by setting its weight to 0 and it is desired that + subsequent otherwise persistent connections are sent to a + different destination server. By default new persistent + connections are allowed to quiescent destination servers. + + If this feature is enabled, the load balancer will expire the + persistence template if it is to be used to schedule a new + connection and the destination server is quiescent. + +nat_icmp_send - BOOLEAN + 0 - disabled (default) + not 0 - enabled + + It controls sending icmp error messages (ICMP_DEST_UNREACH) + for VS/NAT when the load balancer receives packets from real + servers but the connection entries don't exist. + +secure_tcp - INTEGER + 0 - disabled (default) + + The secure_tcp defense is to use a more complicated TCP state + transition table. For VS/NAT, it also delays entering the + TCP ESTABLISHED state until the three way handshake is completed. + + The value definition is the same as that of drop_entry and + drop_packet. + +sync_threshold - INTEGER + default 3 + + It sets synchronization threshold, which is the minimum number + of incoming packets that a connection needs to receive before + the connection will be synchronized. A connection will be + synchronized, every time the number of its incoming packets + modulus 50 equals the threshold. The range of the threshold is + from 0 to 49. + +snat_reroute - BOOLEAN + 0 - disabled + not 0 - enabled (default) + + If enabled, recalculate the route of SNATed packets from + realservers so that they are routed as if they originate from the + director. Otherwise they are routed as if they are forwarded by the + director. + + If policy routing is in effect then it is possible that the route + of a packet originating from a director is routed differently to a + packet being forwarded by the director. + + If policy routing is not in effect then the recalculated route will + always be the same as the original route so it is an optimisation + to disable snat_reroute and avoid the recalculation. + +sync_persist_mode - INTEGER + default 0 + + Controls the synchronisation of connections when using persistence + + 0: All types of connections are synchronised + 1: Attempt to reduce the synchronisation traffic depending on + the connection type. For persistent services avoid synchronisation + for normal connections, do it only for persistence templates. + In such case, for TCP and SCTP it may need enabling sloppy_tcp and + sloppy_sctp flags on backup servers. For non-persistent services + such optimization is not applied, mode 0 is assumed. + +sync_version - INTEGER + default 1 + + The version of the synchronisation protocol used when sending + synchronisation messages. + + 0 selects the original synchronisation protocol (version 0). This + should be used when sending synchronisation messages to a legacy + system that only understands the original synchronisation protocol. + + 1 selects the current synchronisation protocol (version 1). This + should be used where possible. + + Kernels with this sync_version entry are able to receive messages + of both version 1 and version 2 of the synchronisation protocol. |