Disable Path MTU Discovery.
default FALSE
+min_pmtu - INTEGER
+ default 562 - minimum discovered Path MTU
+
+mtu_expires - INTEGER
+ Time, in seconds, that cached PMTU information is kept.
+
+min_adv_mss - INTEGER
+ The advertised MSS depends on the first hop route MTU, but will
+ never be lower than this setting.
+
IP Fragmentation:
ipfrag_high_thresh - INTEGER
for the hash secret) for IP fragments.
Default: 600
+ipfrag_max_dist - INTEGER
+ ipfrag_max_dist is a non-negative integer value which defines the
+ maximum "disorder" which is allowed among fragments which share a
+ common IP source address. Note that reordering of packets is
+ not unusual, but if a large number of fragments arrive from a source
+ IP address while a particular fragment queue remains incomplete, it
+ probably indicates that one or more fragments belonging to that queue
+ have been lost. When ipfrag_max_dist is positive, an additional check
+ is done on fragments before they are added to a reassembly queue - if
+ ipfrag_max_dist (or more) fragments have arrived from a particular IP
+ address between additions to any IP fragment queue using that source
+ address, it's presumed that one or more fragments in the queue are
+ lost. The existing fragment queue will be dropped, and a new one
+ started. An ipfrag_max_dist value of zero disables this check.
+
+ Using a very small value, e.g. 1 or 2, for ipfrag_max_dist can
+ result in unnecessarily dropping fragment queues when normal
+ reordering of packets occurs, which could lead to poor application
+ performance. Using a very large value, e.g. 50000, increases the
+ likelihood of incorrectly reassembling IP fragments that originate
+ from different IP datagrams, which could result in data corruption.
+ Default: 64
+
INET peer storage:
inet_peer_threshold - INTEGER
TCP variables:
+tcp_abc - INTEGER
+ Controls Appropriate Byte Count defined in RFC3465. If set to
+ 0 then does congestion avoid once per ack. 1 is conservative
+ value, and 2 is more agressive.
+
tcp_syn_retries - INTEGER
Number of times initial SYNs for an active TCP connection attempt
will be retransmitted. Should not be higher than 255. Default value
changed would be a Beowulf compute cluster.
Default: 0
-tcp_westwood - BOOLEAN
- Enable TCP Westwood+ congestion control algorithm.
- TCP Westwood+ is a sender-side only modification of the TCP Reno
- protocol stack that optimizes the performance of TCP congestion
- control. It is based on end-to-end bandwidth estimation to set
- congestion window and slow start threshold after a congestion
- episode. Using this estimation, TCP Westwood+ adaptively sets a
- slow start threshold and a congestion window which takes into
- account the bandwidth used at the time congestion is experienced.
- TCP Westwood+ significantly increases fairness wrt TCP Reno in
- wired networks and throughput over wireless links.
- Default: 0
-
-tcp_vegas_cong_avoid - BOOLEAN
- Enable TCP Vegas congestion avoidance algorithm.
- TCP Vegas is a sender-side only change to TCP that anticipates
- the onset of congestion by estimating the bandwidth. TCP Vegas
- adjusts the sending rate by modifying the congestion
- window. TCP Vegas should provide less packet loss, but it is
- not as aggressive as TCP Reno.
- Default:0
-
-tcp_bic - BOOLEAN
- Enable BIC TCP congestion control algorithm.
- BIC-TCP is a sender-side only change that ensures a linear RTT
- fairness under large windows while offering both scalability and
- bounded TCP-friendliness. The protocol combines two schemes
- called additive increase and binary search increase. When the
- congestion window is large, additive increase with a large
- increment ensures linear RTT fairness as well as good
- scalability. Under small congestion windows, binary search
- increase provides TCP friendliness.
+tcp_tso_win_divisor - INTEGER
+ This allows control over what percentage of the congestion window
+ can be consumed by a single TSO frame.
+ The setting of this parameter is a choice between burstiness and
+ building larger TSO frames.
+ Default: 3
+
+tcp_frto - BOOLEAN
+ Enables F-RTO, an enhanced recovery algorithm for TCP retransmission
+ timeouts. It is particularly beneficial in wireless environments
+ where packet loss is typically due to random radio interference
+ rather than intermediate router congestion.
+
+tcp_congestion_control - STRING
+ Set the congestion control algorithm to be used for new
+ connections. The algorithm "reno" is always available, but
+ additional choices may be available based on kernel configuration.
+
+somaxconn - INTEGER
+ Limit of socket listen() backlog, known in userspace as SOMAXCONN.
+ Defaults to 128. See also tcp_max_syn_backlog for additional tuning
+ for TCP sockets.
+
+tcp_workaround_signed_windows - BOOLEAN
+ If set, assume no receipt of a window scaling option means the
+ remote TCP is broken and treats the window as a signed quantity.
+ If unset, assume the remote TCP is not broken even if we do
+ not receive a window scaling option from them.
Default: 0
-tcp_bic_low_window - INTEGER
- Sets the threshold window (in packets) where BIC TCP starts to
- adjust the congestion window. Below this threshold BIC TCP behaves
- the same as the default TCP Reno.
- Default: 14
-
-tcp_bic_fast_convergence - BOOLEAN
- Forces BIC TCP to more quickly respond to changes in congestion
- window. Allows two flows sharing the same connection to converge
- more rapidly.
- Default: 1
-
-tcp_default_win_scale - INTEGER
- Sets the minimum window scale TCP will negotiate for on all
- conections.
- Default: 7
+IP Variables:
ip_local_port_range - 2 INTEGERS
Defines the local port range that is used by TCP and UDP to
Default: 0
icmp_echo_ignore_all - BOOLEAN
+ If set non-zero, then the kernel will ignore all ICMP ECHO
+ requests sent to it.
+ Default: 0
+
icmp_echo_ignore_broadcasts - BOOLEAN
- If either is set to true, then the kernel will ignore either all
- ICMP ECHO requests sent to it or just those to broadcast/multicast
- addresses, respectively.
+ If set non-zero, then the kernel will ignore all ICMP ECHO and
+ TIMESTAMP requests sent to it via broadcast/multicast.
+ Default: 1
icmp_ratelimit - INTEGER
Limit the maximal rates for sending ICMP packets whose type matches
will avoid log file clutter.
Default: FALSE
+icmp_errors_use_inbound_ifaddr - BOOLEAN
+
+ If zero, icmp error messages are sent with the primary address of
+ the exiting interface.
+
+ If non-zero, the message will be sent with the primary address of
+ the interface that received the packet that caused the icmp error.
+ This is the behaviour network many administrators will expect from
+ a router. And it can make debugging complicated network layouts
+ much easier.
+
+ Note that if no primary address exists for the interface selected,
+ then the primary address of the first non-loopback interface that
+ has one will be used regarldess of this setting.
+
+ Default: 0
+
igmp_max_memberships - INTEGER
Change the maximum number of multicast groups we can subscribe to.
Default: 20
The max value from conf/{all,interface}/arp_ignore is used
when ARP request is received on the {interface}
+arp_accept - BOOLEAN
+ Define behavior when gratuitous arp replies are received:
+ 0 - drop gratuitous arp frames
+ 1 - accept gratuitous arp frames
+
+app_solicit - INTEGER
+ The maximum number of probes to send to the user space ARP daemon
+ via netlink before dropping back to multicast probes (see
+ mcast_solicit). Defaults to 0.
+
+disable_policy - BOOLEAN
+ Disable IPSEC policy (SPD) for this interface
+
+disable_xfrm - BOOLEAN
+ Disable IPSEC encryption on this interface, whatever the policy
+
+
+
tag - INTEGER
Allows you to write a number, which can be used as required.
Default value is 0.
Functional default: enabled if local forwarding is disabled.
disabled if local forwarding is enabled.
+accept_ra_defrtr - BOOLEAN
+ Learn default router in Router Advertisement.
+
+ Functional default: enabled if accept_ra is enabled.
+ disabled if accept_ra is disabled.
+
+accept_ra_pinfo - BOOLEAN
+ Learn Prefix Inforamtion in Router Advertisement.
+
+ Functional default: enabled if accept_ra is enabled.
+ disabled if accept_ra is disabled.
+
+accept_ra_rt_info_max_plen - INTEGER
+ Maximum prefix length of Route Information in RA.
+
+ Route Information w/ prefix larger than or equal to this
+ variable shall be ignored.
+
+ Functional default: 0 if accept_ra_rtr_pref is enabled.
+ -1 if accept_ra_rtr_pref is disabled.
+
+accept_ra_rtr_pref - BOOLEAN
+ Accept Router Preference in RA.
+
+ Functional default: enabled if accept_ra is enabled.
+ disabled if accept_ra is disabled.
+
accept_redirects - BOOLEAN
Accept Redirects.
disabled if local forwarding is enabled.
autoconf - BOOLEAN
- Configure link-local addresses using L2 hardware addresses.
+ Autoconfigure addresses using Prefix Information in Router
+ Advertisements.
- Default: TRUE
+ Functional default: enabled if accept_ra_pinfo is enabled.
+ disabled if accept_ra_pinfo is disabled.
dad_transmits - INTEGER
The amount of Duplicate Address Detection probes to send.
Default Maximum Transfer Unit
Default: 1280 (IPv6 required minimum)
+router_probe_interval - INTEGER
+ Minimum interval (in seconds) between Router Probing described
+ in RFC4191.
+
+ Default: 60
+
router_solicitation_delay - INTEGER
Number of seconds to wait after interface is brought up
before sending Router Solicitations.
0 : disable this.
Default: 1
+bridge-nf-call-ip6tables - BOOLEAN
+ 1 : pass bridged IPv6 traffic to ip6tables' chains.
+ 0 : disable this.
+ Default: 1
+
bridge-nf-filter-vlan-tagged - BOOLEAN
1 : pass bridged vlan-tagged ARP/IP traffic to arptables/iptables.
0 : disable this.
Default: 1
+UNDOCUMENTED:
+
+dev_weight FIXME
+discovery_slots FIXME
+discovery_timeout FIXME
+fast_poll_increase FIXME
+ip6_queue_maxlen FIXME
+lap_keepalive_time FIXME
+lo_cong FIXME
+max_baud_rate FIXME
+max_dgram_qlen FIXME
+max_noreply_time FIXME
+max_tx_data_size FIXME
+max_tx_window FIXME
+min_tx_turn_time FIXME
+mod_cong FIXME
+no_cong FIXME
+no_cong_thresh FIXME
+slot_timeout FIXME
+warn_noreply_time FIXME
+
$Id: ip-sysctl.txt,v 1.20 2001/12/13 09:00:18 davem Exp $
git://git.onelab.eu / linux-2.6.git / blobdiff