net/ipv4/Kconfig - kernel/msm-4.9 - Gitiles

 #
 # IP configuration
 #
 config IP_MULTICAST
 	bool "IP: multicasting"
 	help
 	  This is code for addressing several networked computers at once,
 	  enlarging your kernel by about 2 KB. You need multicasting if you
 	  intend to participate in the MBONE, a high bandwidth network on top
 	  of the Internet which carries audio and video broadcasts. More
 	  information about the MBONE is on the WWW at
 	  <http://www-itg.lbl.gov/mbone/>. Information about the multicast
 	  capabilities of the various network cards is contained in
 	  <file:Documentation/networking/multicast.txt>. For most people, it's
 	  safe to say N.

 config IP_ADVANCED_ROUTER
 	bool "IP: advanced router"
 	---help---
 	  If you intend to run your Linux box mostly as a router, i.e. as a
 	  computer that forwards and redistributes network packets, say Y; you
 	  will then be presented with several options that allow more precise
 	  control about the routing process.

 	  The answer to this question won't directly affect the kernel:
 	  answering N will just cause the configurator to skip all the
 	  questions about advanced routing.

 	  Note that your box can only act as a router if you enable IP
 	  forwarding in your kernel; you can do that by saying Y to "/proc
 	  file system support" and "Sysctl support" below and executing the
 	  line

 	  echo "1" > /proc/sys/net/ipv4/ip_forward

 	  at boot time after the /proc file system has been mounted.

 	  If you turn on IP forwarding, you will also get the rp_filter, which
 	  automatically rejects incoming packets if the routing table entry
 	  for their source address doesn't match the network interface they're
 	  arriving on. This has security advantages because it prevents the
 	  so-called IP spoofing, however it can pose problems if you use
 	  asymmetric routing (packets from you to a host take a different path
 	  than packets from that host to you) or if you operate a non-routing
 	  host which has several IP addresses on different interfaces. To turn
 	  rp_filter off use:

 	  echo 0 > /proc/sys/net/ipv4/conf/<device>/rp_filter
 	  or
 	  echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter

 	  If unsure, say N here.

 choice
 	prompt "Choose IP: FIB lookup algorithm (choose FIB_HASH if unsure)"
 	depends on IP_ADVANCED_ROUTER
 	default IP_FIB_HASH

 config IP_FIB_HASH
 	bool "FIB_HASH"
 	---help---
 	Current FIB is very proven and good enough for most users.

 config IP_FIB_TRIE
 	bool "FIB_TRIE"
 	---help---
 	Use new experimental LC-trie as FIB lookup algoritm.
         This improves lookup performance if you have a large
 	number of routes.

 	LC-trie is a longest matching prefix lookup algorithm which
 	performs better than FIB_HASH for large routing tables.
 	But, it consumes more memory and is more complex.

 	LC-trie is described in:

  	IP-address lookup using LC-tries. Stefan Nilsson and Gunnar Karlsson
  	IEEE Journal on Selected Areas in Communications, 17(6):1083-1092, June 1999
 	An experimental study of compression methods for dynamic tries
  	Stefan Nilsson and Matti Tikkanen. Algorithmica, 33(1):19-33, 2002.
  	http://www.nada.kth.se/~snilsson/public/papers/dyntrie2/

 endchoice

 # If the user does not enable advanced routing, he gets the safe
 # default of the fib-hash algorithm.
 config IP_FIB_HASH
 	bool
 	depends on !IP_ADVANCED_ROUTER
 	default y

 config IP_MULTIPLE_TABLES
 	bool "IP: policy routing"
 	depends on IP_ADVANCED_ROUTER
 	---help---
 	  Normally, a router decides what to do with a received packet based
 	  solely on the packet's final destination address. If you say Y here,
 	  the Linux router will also be able to take the packet's source
 	  address into account. Furthermore, the TOS (Type-Of-Service) field
 	  of the packet can be used for routing decisions as well.

 	  If you are interested in this, please see the preliminary
 	  documentation at <http://www.compendium.com.ar/policy-routing.txt>
 	  and <ftp://post.tepkom.ru/pub/vol2/Linux/docs/advanced-routing.tex>.
 	  You will need supporting software from
 	  <ftp://ftp.tux.org/pub/net/ip-routing/>.

 	  If unsure, say N.

 config IP_ROUTE_FWMARK
 	bool "IP: use netfilter MARK value as routing key"
 	depends on IP_MULTIPLE_TABLES && NETFILTER
 	help
 	  If you say Y here, you will be able to specify different routes for
 	  packets with different mark values (see iptables(8), MARK target).

 config IP_ROUTE_MULTIPATH
 	bool "IP: equal cost multipath"
 	depends on IP_ADVANCED_ROUTER
 	help
 	  Normally, the routing tables specify a single action to be taken in
 	  a deterministic manner for a given packet. If you say Y here
 	  however, it becomes possible to attach several actions to a packet
 	  pattern, in effect specifying several alternative paths to travel
 	  for those packets. The router considers all these paths to be of
 	  equal "cost" and chooses one of them in a non-deterministic fashion
 	  if a matching packet arrives.

 config IP_ROUTE_MULTIPATH_CACHED
 	bool "IP: equal cost multipath with caching support (EXPERIMENTAL)"
 	depends on: IP_ROUTE_MULTIPATH
 	help
 	  Normally, equal cost multipath routing is not supported by the
 	  routing cache. If you say Y here, alternative routes are cached
 	  and on cache lookup a route is chosen in a configurable fashion.

 	  If unsure, say N.

 config IP_ROUTE_MULTIPATH_RR
 	tristate "MULTIPATH: round robin algorithm"
 	depends on IP_ROUTE_MULTIPATH_CACHED
 	help
 	  Mulitpath routes are chosen according to Round Robin

 config IP_ROUTE_MULTIPATH_RANDOM
 	tristate "MULTIPATH: random algorithm"
 	depends on IP_ROUTE_MULTIPATH_CACHED
 	help
 	  Multipath routes are chosen in a random fashion. Actually,
 	  there is no weight for a route. The advantage of this policy
 	  is that it is implemented stateless and therefore introduces only
 	  a very small delay.

 config IP_ROUTE_MULTIPATH_WRANDOM
 	tristate "MULTIPATH: weighted random algorithm"
 	depends on IP_ROUTE_MULTIPATH_CACHED
 	help
 	  Multipath routes are chosen in a weighted random fashion.
 	  The per route weights are the weights visible via ip route 2. As the
 	  corresponding state management introduces some overhead routing delay
 	  is increased.

 config IP_ROUTE_MULTIPATH_DRR
 	tristate "MULTIPATH: interface round robin algorithm"
 	depends on IP_ROUTE_MULTIPATH_CACHED
 	help
 	  Connections are distributed in a round robin fashion over the
 	  available interfaces. This policy makes sense if the connections
 	  should be primarily distributed on interfaces and not on routes.

 config IP_ROUTE_VERBOSE
 	bool "IP: verbose route monitoring"
 	depends on IP_ADVANCED_ROUTER
 	help
 	  If you say Y here, which is recommended, then the kernel will print
 	  verbose messages regarding the routing, for example warnings about
 	  received packets which look strange and could be evidence of an
 	  attack or a misconfigured system somewhere. The information is
 	  handled by the klogd daemon which is responsible for kernel messages
 	  ("man klogd").

 config IP_PNP
 	bool "IP: kernel level autoconfiguration"
 	help
 	  This enables automatic configuration of IP addresses of devices and
 	  of the routing table during kernel boot, based on either information
 	  supplied on the kernel command line or by BOOTP or RARP protocols.
 	  You need to say Y only for diskless machines requiring network
 	  access to boot (in which case you want to say Y to "Root file system
 	  on NFS" as well), because all other machines configure the network
 	  in their startup scripts.

 config IP_PNP_DHCP
 	bool "IP: DHCP support"
 	depends on IP_PNP
 	---help---
 	  If you want your Linux box to mount its whole root file system (the
 	  one containing the directory /) from some other computer over the
 	  net via NFS and you want the IP address of your computer to be
 	  discovered automatically at boot time using the DHCP protocol (a
 	  special protocol designed for doing this job), say Y here. In case
 	  the boot ROM of your network card was designed for booting Linux and
 	  does DHCP itself, providing all necessary information on the kernel
 	  command line, you can say N here.

 	  If unsure, say Y. Note that if you want to use DHCP, a DHCP server
 	  must be operating on your network.  Read
 	  <file:Documentation/nfsroot.txt> for details.

 config IP_PNP_BOOTP
 	bool "IP: BOOTP support"
 	depends on IP_PNP
 	---help---
 	  If you want your Linux box to mount its whole root file system (the
 	  one containing the directory /) from some other computer over the
 	  net via NFS and you want the IP address of your computer to be
 	  discovered automatically at boot time using the BOOTP protocol (a
 	  special protocol designed for doing this job), say Y here. In case
 	  the boot ROM of your network card was designed for booting Linux and
 	  does BOOTP itself, providing all necessary information on the kernel
 	  command line, you can say N here. If unsure, say Y. Note that if you
 	  want to use BOOTP, a BOOTP server must be operating on your network.
 	  Read <file:Documentation/nfsroot.txt> for details.

 config IP_PNP_RARP
 	bool "IP: RARP support"
 	depends on IP_PNP
 	help
 	  If you want your Linux box to mount its whole root file system (the
 	  one containing the directory /) from some other computer over the
 	  net via NFS and you want the IP address of your computer to be
 	  discovered automatically at boot time using the RARP protocol (an
 	  older protocol which is being obsoleted by BOOTP and DHCP), say Y
 	  here. Note that if you want to use RARP, a RARP server must be
 	  operating on your network. Read <file:Documentation/nfsroot.txt> for
 	  details.

 # not yet ready..
 #   bool '    IP: ARP support' CONFIG_IP_PNP_ARP
 config NET_IPIP
 	tristate "IP: tunneling"
 	select INET_TUNNEL
 	---help---
 	  Tunneling means encapsulating data of one protocol type within
 	  another protocol and sending it over a channel that understands the
 	  encapsulating protocol. This particular tunneling driver implements
 	  encapsulation of IP within IP, which sounds kind of pointless, but
 	  can be useful if you want to make your (or some other) machine
 	  appear on a different network than it physically is, or to use
 	  mobile-IP facilities (allowing laptops to seamlessly move between
 	  networks without changing their IP addresses).

 	  Saying Y to this option will produce two modules ( = code which can
 	  be inserted in and removed from the running kernel whenever you
 	  want). Most people won't need this and can say N.

 config NET_IPGRE
 	tristate "IP: GRE tunnels over IP"
 	select XFRM
 	help
 	  Tunneling means encapsulating data of one protocol type within
 	  another protocol and sending it over a channel that understands the
 	  encapsulating protocol. This particular tunneling driver implements
 	  GRE (Generic Routing Encapsulation) and at this time allows
 	  encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure.
 	  This driver is useful if the other endpoint is a Cisco router: Cisco
 	  likes GRE much better than the other Linux tunneling driver ("IP
 	  tunneling" above). In addition, GRE allows multicast redistribution
 	  through the tunnel.

 config NET_IPGRE_BROADCAST
 	bool "IP: broadcast GRE over IP"
 	depends on IP_MULTICAST && NET_IPGRE
 	help
 	  One application of GRE/IP is to construct a broadcast WAN (Wide Area
 	  Network), which looks like a normal Ethernet LAN (Local Area
 	  Network), but can be distributed all over the Internet. If you want
 	  to do that, say Y here and to "IP multicast routing" below.

 config IP_MROUTE
 	bool "IP: multicast routing"
 	depends on IP_MULTICAST
 	help
 	  This is used if you want your machine to act as a router for IP
 	  packets that have several destination addresses. It is needed on the
 	  MBONE, a high bandwidth network on top of the Internet which carries
 	  audio and video broadcasts. In order to do that, you would most
 	  likely run the program mrouted. Information about the multicast
 	  capabilities of the various network cards is contained in
 	  <file:Documentation/networking/multicast.txt>. If you haven't heard
 	  about it, you don't need it.

 config IP_PIMSM_V1
 	bool "IP: PIM-SM version 1 support"
 	depends on IP_MROUTE
 	help
 	  Kernel side support for Sparse Mode PIM (Protocol Independent
 	  Multicast) version 1. This multicast routing protocol is used widely
 	  because Cisco supports it. You need special software to use it
 	  (pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
 	  information about PIM.

 	  Say Y if you want to use PIM-SM v1. Note that you can say N here if
 	  you just want to use Dense Mode PIM.

 config IP_PIMSM_V2
 	bool "IP: PIM-SM version 2 support"
 	depends on IP_MROUTE
 	help
 	  Kernel side support for Sparse Mode PIM version 2. In order to use
 	  this, you need an experimental routing daemon supporting it (pimd or
 	  gated-5). This routing protocol is not used widely, so say N unless
 	  you want to play with it.

 config ARPD
 	bool "IP: ARP daemon support (EXPERIMENTAL)"
 	depends on EXPERIMENTAL
 	---help---
 	  Normally, the kernel maintains an internal cache which maps IP
 	  addresses to hardware addresses on the local network, so that
 	  Ethernet/Token Ring/ etc. frames are sent to the proper address on
 	  the physical networking layer. For small networks having a few
 	  hundred directly connected hosts or less, keeping this address
 	  resolution (ARP) cache inside the kernel works well. However,
 	  maintaining an internal ARP cache does not work well for very large
 	  switched networks, and will use a lot of kernel memory if TCP/IP
 	  connections are made to many machines on the network.

 	  If you say Y here, the kernel's internal ARP cache will never grow
 	  to more than 256 entries (the oldest entries are expired in a LIFO
 	  manner) and communication will be attempted with the user space ARP
 	  daemon arpd. Arpd then answers the address resolution request either
 	  from its own cache or by asking the net.

 	  This code is experimental and also obsolete. If you want to use it,
 	  you need to find a version of the daemon arpd on the net somewhere,
 	  and you should also say Y to "Kernel/User network link driver",
 	  below. If unsure, say N.

 config SYN_COOKIES
 	bool "IP: TCP syncookie support (disabled per default)"
 	---help---
 	  Normal TCP/IP networking is open to an attack known as "SYN
 	  flooding". This denial-of-service attack prevents legitimate remote
 	  users from being able to connect to your computer during an ongoing
 	  attack and requires very little work from the attacker, who can
 	  operate from anywhere on the Internet.

 	  SYN cookies provide protection against this type of attack. If you
 	  say Y here, the TCP/IP stack will use a cryptographic challenge
 	  protocol known as "SYN cookies" to enable legitimate users to
 	  continue to connect, even when your machine is under attack. There
 	  is no need for the legitimate users to change their TCP/IP software;
 	  SYN cookies work transparently to them. For technical information
 	  about SYN cookies, check out <http://cr.yp.to/syncookies.html>.

 	  If you are SYN flooded, the source address reported by the kernel is
 	  likely to have been forged by the attacker; it is only reported as
 	  an aid in tracing the packets to their actual source and should not
 	  be taken as absolute truth.

 	  SYN cookies may prevent correct error reporting on clients when the
 	  server is really overloaded. If this happens frequently better turn
 	  them off.

 	  If you say Y here, note that SYN cookies aren't enabled by default;
 	  you can enable them by saying Y to "/proc file system support" and
 	  "Sysctl support" below and executing the command

 	  echo 1 >/proc/sys/net/ipv4/tcp_syncookies

 	  at boot time after the /proc file system has been mounted.

 	  If unsure, say N.

 config INET_AH
 	tristate "IP: AH transformation"
 	select XFRM
 	select CRYPTO
 	select CRYPTO_HMAC
 	select CRYPTO_MD5
 	select CRYPTO_SHA1
 	---help---
 	  Support for IPsec AH.

 	  If unsure, say Y.

 config INET_ESP
 	tristate "IP: ESP transformation"
 	select XFRM
 	select CRYPTO
 	select CRYPTO_HMAC
 	select CRYPTO_MD5
 	select CRYPTO_SHA1
 	select CRYPTO_DES
 	---help---
 	  Support for IPsec ESP.

 	  If unsure, say Y.

 config INET_IPCOMP
 	tristate "IP: IPComp transformation"
 	select XFRM
 	select INET_TUNNEL
 	select CRYPTO
 	select CRYPTO_DEFLATE
 	---help---
 	  Support for IP Payload Compression Protocol (IPComp) (RFC3173),
 	  typically needed for IPsec.

 	  If unsure, say Y.

 config INET_TUNNEL
 	tristate "IP: tunnel transformation"
 	select XFRM
 	---help---
 	  Support for generic IP tunnel transformation, which is required by
 	  the IP tunneling module as well as tunnel mode IPComp.

 	  If unsure, say Y.

 config IP_TCPDIAG
 	tristate "IP: TCP socket monitoring interface"
 	default y
 	---help---
 	  Support for TCP socket monitoring interface used by native Linux
 	  tools such as ss. ss is included in iproute2, currently downloadable
 	  at <http://developer.osdl.org/dev/iproute2>. If you want IPv6 support
 	  and have selected IPv6 as a module, you need to build this as a
 	  module too.

 	  If unsure, say Y.

 config IP_TCPDIAG_IPV6
 	def_bool (IP_TCPDIAG=y && IPV6=y) || (IP_TCPDIAG=m && IPV6)

 config TCP_CONG_ADVANCED
 	bool "TCP: advanced congestion control"
 	---help---
 	  Support for selection of various TCP congestion control
 	  modules.

 	  Nearly all users can safely say no here, and a safe default
 	  selection will be made (BIC-TCP with new Reno as a fallback).

 	  If unsure, say N.

 # TCP Reno is builtin (required as fallback)
 menu "TCP congestion control"
 	depends on TCP_CONG_ADVANCED

 config TCP_CONG_BIC
 	tristate "Binary Increase Congestion (BIC) control"
 	default y
 	---help---
 	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.
 	See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/

 config TCP_CONG_WESTWOOD
 	tristate "TCP Westwood+"
 	default m
 	---help---
 	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.

 config TCP_CONG_HTCP
         tristate "H-TCP"
         default m
 	---help---
 	H-TCP is a send-side only modifications of the TCP Reno
 	protocol stack that optimizes the performance of TCP
 	congestion control for high speed network links. It uses a
 	modeswitch to change the alpha and beta parameters of TCP Reno
 	based on network conditions and in a way so as to be fair with
 	other Reno and H-TCP flows.

 config TCP_CONG_HSTCP
 	tristate "High Speed TCP"
 	depends on EXPERIMENTAL
 	default n
 	---help---
 	Sally Floyd's High Speed TCP (RFC 3649) congestion control.
 	A modification to TCP's congestion control mechanism for use
 	with large congestion windows. A table indicates how much to
 	increase the congestion window by when an ACK is received.
  	For more detail	see http://www.icir.org/floyd/hstcp.html

 config TCP_CONG_HYBLA
 	tristate "TCP-Hybla congestion control algorithm"
 	depends on EXPERIMENTAL
 	default n
 	---help---
 	TCP-Hybla is a sender-side only change that eliminates penalization of
 	long-RTT, large-bandwidth connections, like when satellite legs are
 	involved, expecially when sharing a common bottleneck with normal
 	terrestrial connections.

 config TCP_CONG_VEGAS
 	tristate "TCP Vegas"
 	depends on EXPERIMENTAL
 	default n
 	---help---
 	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.

 config TCP_CONG_SCALABLE
 	tristate "Scalable TCP"
 	depends on EXPERIMENTAL
 	default n
 	---help---
 	Scalable TCP is a sender-side only change to TCP which uses a
 	MIMD congestion control algorithm which has some nice scaling
 	properties, though is known to have fairness issues.
 	See http://www-lce.eng.cam.ac.uk/~ctk21/scalable/

 endmenu

 config TCP_CONG_BIC
 	tristate
 	depends on !TCP_CONG_ADVANCED
 	default y

 source "net/ipv4/ipvs/Kconfig"
	#
	# IP configuration
	#
	config IP_MULTICAST
	bool "IP: multicasting"
	help
	This is code for addressing several networked computers at once,
	enlarging your kernel by about 2 KB. You need multicasting if you
	intend to participate in the MBONE, a high bandwidth network on top
	of the Internet which carries audio and video broadcasts. More
	information about the MBONE is on the WWW at
	<http://www-itg.lbl.gov/mbone/>. Information about the multicast
	capabilities of the various network cards is contained in
	<file:Documentation/networking/multicast.txt>. For most people, it's
	safe to say N.

	config IP_ADVANCED_ROUTER
	bool "IP: advanced router"
	---help---
	If you intend to run your Linux box mostly as a router, i.e. as a
	computer that forwards and redistributes network packets, say Y; you
	will then be presented with several options that allow more precise
	control about the routing process.

	The answer to this question won't directly affect the kernel:
	answering N will just cause the configurator to skip all the
	questions about advanced routing.

	Note that your box can only act as a router if you enable IP
	forwarding in your kernel; you can do that by saying Y to "/proc
	file system support" and "Sysctl support" below and executing the
	line

	echo "1" > /proc/sys/net/ipv4/ip_forward

	at boot time after the /proc file system has been mounted.

	If you turn on IP forwarding, you will also get the rp_filter, which
	automatically rejects incoming packets if the routing table entry
	for their source address doesn't match the network interface they're
	arriving on. This has security advantages because it prevents the
	so-called IP spoofing, however it can pose problems if you use
	asymmetric routing (packets from you to a host take a different path
	than packets from that host to you) or if you operate a non-routing
	host which has several IP addresses on different interfaces. To turn
	rp_filter off use:

	echo 0 > /proc/sys/net/ipv4/conf/<device>/rp_filter
	or
	echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter

	If unsure, say N here.

	choice
	prompt "Choose IP: FIB lookup algorithm (choose FIB_HASH if unsure)"
	depends on IP_ADVANCED_ROUTER
	default IP_FIB_HASH

	config IP_FIB_HASH
	bool "FIB_HASH"
	---help---
	Current FIB is very proven and good enough for most users.

	config IP_FIB_TRIE
	bool "FIB_TRIE"
	---help---
	Use new experimental LC-trie as FIB lookup algoritm.
	This improves lookup performance if you have a large
	number of routes.

	LC-trie is a longest matching prefix lookup algorithm which
	performs better than FIB_HASH for large routing tables.
	But, it consumes more memory and is more complex.

	LC-trie is described in:

	IP-address lookup using LC-tries. Stefan Nilsson and Gunnar Karlsson
	IEEE Journal on Selected Areas in Communications, 17(6):1083-1092, June 1999
	An experimental study of compression methods for dynamic tries
	Stefan Nilsson and Matti Tikkanen. Algorithmica, 33(1):19-33, 2002.
	http://www.nada.kth.se/~snilsson/public/papers/dyntrie2/

	endchoice

	# If the user does not enable advanced routing, he gets the safe
	# default of the fib-hash algorithm.
	config IP_FIB_HASH
	bool
	depends on !IP_ADVANCED_ROUTER
	default y

	config IP_MULTIPLE_TABLES
	bool "IP: policy routing"
	depends on IP_ADVANCED_ROUTER
	---help---
	Normally, a router decides what to do with a received packet based
	solely on the packet's final destination address. If you say Y here,
	the Linux router will also be able to take the packet's source
	address into account. Furthermore, the TOS (Type-Of-Service) field
	of the packet can be used for routing decisions as well.

	If you are interested in this, please see the preliminary
	documentation at <http://www.compendium.com.ar/policy-routing.txt>
	and <ftp://post.tepkom.ru/pub/vol2/Linux/docs/advanced-routing.tex>.
	You will need supporting software from
	<ftp://ftp.tux.org/pub/net/ip-routing/>.

	If unsure, say N.

	config IP_ROUTE_FWMARK
	bool "IP: use netfilter MARK value as routing key"
	depends on IP_MULTIPLE_TABLES && NETFILTER
	help
	If you say Y here, you will be able to specify different routes for
	packets with different mark values (see iptables(8), MARK target).

	config IP_ROUTE_MULTIPATH
	bool "IP: equal cost multipath"
	depends on IP_ADVANCED_ROUTER
	help
	Normally, the routing tables specify a single action to be taken in
	a deterministic manner for a given packet. If you say Y here
	however, it becomes possible to attach several actions to a packet
	pattern, in effect specifying several alternative paths to travel
	for those packets. The router considers all these paths to be of
	equal "cost" and chooses one of them in a non-deterministic fashion
	if a matching packet arrives.

	config IP_ROUTE_MULTIPATH_CACHED
	bool "IP: equal cost multipath with caching support (EXPERIMENTAL)"
	depends on: IP_ROUTE_MULTIPATH
	help
	Normally, equal cost multipath routing is not supported by the
	routing cache. If you say Y here, alternative routes are cached
	and on cache lookup a route is chosen in a configurable fashion.

	If unsure, say N.

	config IP_ROUTE_MULTIPATH_RR
	tristate "MULTIPATH: round robin algorithm"
	depends on IP_ROUTE_MULTIPATH_CACHED
	help
	Mulitpath routes are chosen according to Round Robin

	config IP_ROUTE_MULTIPATH_RANDOM
	tristate "MULTIPATH: random algorithm"
	depends on IP_ROUTE_MULTIPATH_CACHED
	help
	Multipath routes are chosen in a random fashion. Actually,
	there is no weight for a route. The advantage of this policy
	is that it is implemented stateless and therefore introduces only
	a very small delay.

	config IP_ROUTE_MULTIPATH_WRANDOM
	tristate "MULTIPATH: weighted random algorithm"
	depends on IP_ROUTE_MULTIPATH_CACHED
	help
	Multipath routes are chosen in a weighted random fashion.
	The per route weights are the weights visible via ip route 2. As the
	corresponding state management introduces some overhead routing delay
	is increased.

	config IP_ROUTE_MULTIPATH_DRR
	tristate "MULTIPATH: interface round robin algorithm"
	depends on IP_ROUTE_MULTIPATH_CACHED
	help
	Connections are distributed in a round robin fashion over the
	available interfaces. This policy makes sense if the connections
	should be primarily distributed on interfaces and not on routes.

	config IP_ROUTE_VERBOSE
	bool "IP: verbose route monitoring"
	depends on IP_ADVANCED_ROUTER
	help
	If you say Y here, which is recommended, then the kernel will print
	verbose messages regarding the routing, for example warnings about
	received packets which look strange and could be evidence of an
	attack or a misconfigured system somewhere. The information is
	handled by the klogd daemon which is responsible for kernel messages
	("man klogd").

	config IP_PNP
	bool "IP: kernel level autoconfiguration"
	help
	This enables automatic configuration of IP addresses of devices and
	of the routing table during kernel boot, based on either information
	supplied on the kernel command line or by BOOTP or RARP protocols.
	You need to say Y only for diskless machines requiring network
	access to boot (in which case you want to say Y to "Root file system
	on NFS" as well), because all other machines configure the network
	in their startup scripts.

	config IP_PNP_DHCP
	bool "IP: DHCP support"
	depends on IP_PNP
	---help---
	If you want your Linux box to mount its whole root file system (the
	one containing the directory /) from some other computer over the
	net via NFS and you want the IP address of your computer to be
	discovered automatically at boot time using the DHCP protocol (a
	special protocol designed for doing this job), say Y here. In case
	the boot ROM of your network card was designed for booting Linux and
	does DHCP itself, providing all necessary information on the kernel
	command line, you can say N here.

	If unsure, say Y. Note that if you want to use DHCP, a DHCP server
	must be operating on your network. Read
	<file:Documentation/nfsroot.txt> for details.

	config IP_PNP_BOOTP
	bool "IP: BOOTP support"
	depends on IP_PNP
	---help---
	If you want your Linux box to mount its whole root file system (the
	one containing the directory /) from some other computer over the
	net via NFS and you want the IP address of your computer to be
	discovered automatically at boot time using the BOOTP protocol (a
	special protocol designed for doing this job), say Y here. In case
	the boot ROM of your network card was designed for booting Linux and
	does BOOTP itself, providing all necessary information on the kernel
	command line, you can say N here. If unsure, say Y. Note that if you
	want to use BOOTP, a BOOTP server must be operating on your network.
	Read <file:Documentation/nfsroot.txt> for details.

	config IP_PNP_RARP
	bool "IP: RARP support"
	depends on IP_PNP
	help
	If you want your Linux box to mount its whole root file system (the
	one containing the directory /) from some other computer over the
	net via NFS and you want the IP address of your computer to be
	discovered automatically at boot time using the RARP protocol (an
	older protocol which is being obsoleted by BOOTP and DHCP), say Y
	here. Note that if you want to use RARP, a RARP server must be
	operating on your network. Read <file:Documentation/nfsroot.txt> for
	details.

	# not yet ready..
	# bool ' IP: ARP support' CONFIG_IP_PNP_ARP
	config NET_IPIP
	tristate "IP: tunneling"
	select INET_TUNNEL
	---help---
	Tunneling means encapsulating data of one protocol type within
	another protocol and sending it over a channel that understands the
	encapsulating protocol. This particular tunneling driver implements
	encapsulation of IP within IP, which sounds kind of pointless, but
	can be useful if you want to make your (or some other) machine
	appear on a different network than it physically is, or to use
	mobile-IP facilities (allowing laptops to seamlessly move between
	networks without changing their IP addresses).

	Saying Y to this option will produce two modules ( = code which can
	be inserted in and removed from the running kernel whenever you
	want). Most people won't need this and can say N.

	config NET_IPGRE
	tristate "IP: GRE tunnels over IP"
	select XFRM
	help
	Tunneling means encapsulating data of one protocol type within
	another protocol and sending it over a channel that understands the
	encapsulating protocol. This particular tunneling driver implements
	GRE (Generic Routing Encapsulation) and at this time allows
	encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure.
	This driver is useful if the other endpoint is a Cisco router: Cisco
	likes GRE much better than the other Linux tunneling driver ("IP
	tunneling" above). In addition, GRE allows multicast redistribution
	through the tunnel.

	config NET_IPGRE_BROADCAST
	bool "IP: broadcast GRE over IP"
	depends on IP_MULTICAST && NET_IPGRE
	help
	One application of GRE/IP is to construct a broadcast WAN (Wide Area
	Network), which looks like a normal Ethernet LAN (Local Area
	Network), but can be distributed all over the Internet. If you want
	to do that, say Y here and to "IP multicast routing" below.

	config IP_MROUTE
	bool "IP: multicast routing"
	depends on IP_MULTICAST
	help
	This is used if you want your machine to act as a router for IP
	packets that have several destination addresses. It is needed on the
	MBONE, a high bandwidth network on top of the Internet which carries
	audio and video broadcasts. In order to do that, you would most
	likely run the program mrouted. Information about the multicast
	capabilities of the various network cards is contained in
	<file:Documentation/networking/multicast.txt>. If you haven't heard
	about it, you don't need it.

	config IP_PIMSM_V1
	bool "IP: PIM-SM version 1 support"
	depends on IP_MROUTE
	help
	Kernel side support for Sparse Mode PIM (Protocol Independent
	Multicast) version 1. This multicast routing protocol is used widely
	because Cisco supports it. You need special software to use it
	(pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
	information about PIM.

	Say Y if you want to use PIM-SM v1. Note that you can say N here if
	you just want to use Dense Mode PIM.

	config IP_PIMSM_V2
	bool "IP: PIM-SM version 2 support"
	depends on IP_MROUTE
	help
	Kernel side support for Sparse Mode PIM version 2. In order to use
	this, you need an experimental routing daemon supporting it (pimd or
	gated-5). This routing protocol is not used widely, so say N unless
	you want to play with it.

	config ARPD
	bool "IP: ARP daemon support (EXPERIMENTAL)"
	depends on EXPERIMENTAL
	---help---
	Normally, the kernel maintains an internal cache which maps IP
	addresses to hardware addresses on the local network, so that
	Ethernet/Token Ring/ etc. frames are sent to the proper address on
	the physical networking layer. For small networks having a few
	hundred directly connected hosts or less, keeping this address
	resolution (ARP) cache inside the kernel works well. However,
	maintaining an internal ARP cache does not work well for very large
	switched networks, and will use a lot of kernel memory if TCP/IP
	connections are made to many machines on the network.

	If you say Y here, the kernel's internal ARP cache will never grow
	to more than 256 entries (the oldest entries are expired in a LIFO
	manner) and communication will be attempted with the user space ARP
	daemon arpd. Arpd then answers the address resolution request either
	from its own cache or by asking the net.

	This code is experimental and also obsolete. If you want to use it,
	you need to find a version of the daemon arpd on the net somewhere,
	and you should also say Y to "Kernel/User network link driver",
	below. If unsure, say N.

	config SYN_COOKIES
	bool "IP: TCP syncookie support (disabled per default)"
	---help---
	Normal TCP/IP networking is open to an attack known as "SYN
	flooding". This denial-of-service attack prevents legitimate remote
	users from being able to connect to your computer during an ongoing
	attack and requires very little work from the attacker, who can
	operate from anywhere on the Internet.

	SYN cookies provide protection against this type of attack. If you
	say Y here, the TCP/IP stack will use a cryptographic challenge
	protocol known as "SYN cookies" to enable legitimate users to
	continue to connect, even when your machine is under attack. There
	is no need for the legitimate users to change their TCP/IP software;
	SYN cookies work transparently to them. For technical information
	about SYN cookies, check out <http://cr.yp.to/syncookies.html>.

	If you are SYN flooded, the source address reported by the kernel is
	likely to have been forged by the attacker; it is only reported as
	an aid in tracing the packets to their actual source and should not
	be taken as absolute truth.

	SYN cookies may prevent correct error reporting on clients when the
	server is really overloaded. If this happens frequently better turn
	them off.

	If you say Y here, note that SYN cookies aren't enabled by default;
	you can enable them by saying Y to "/proc file system support" and
	"Sysctl support" below and executing the command

	echo 1 >/proc/sys/net/ipv4/tcp_syncookies

	at boot time after the /proc file system has been mounted.

	If unsure, say N.

	config INET_AH
	tristate "IP: AH transformation"
	select XFRM
	select CRYPTO
	select CRYPTO_HMAC
	select CRYPTO_MD5
	select CRYPTO_SHA1
	---help---
	Support for IPsec AH.

	If unsure, say Y.

	config INET_ESP
	tristate "IP: ESP transformation"
	select XFRM
	select CRYPTO
	select CRYPTO_HMAC
	select CRYPTO_MD5
	select CRYPTO_SHA1
	select CRYPTO_DES
	---help---
	Support for IPsec ESP.

	If unsure, say Y.

	config INET_IPCOMP
	tristate "IP: IPComp transformation"
	select XFRM
	select INET_TUNNEL
	select CRYPTO
	select CRYPTO_DEFLATE
	---help---
	Support for IP Payload Compression Protocol (IPComp) (RFC3173),
	typically needed for IPsec.

	If unsure, say Y.

	config INET_TUNNEL
	tristate "IP: tunnel transformation"
	select XFRM
	---help---
	Support for generic IP tunnel transformation, which is required by
	the IP tunneling module as well as tunnel mode IPComp.

	If unsure, say Y.

	config IP_TCPDIAG
	tristate "IP: TCP socket monitoring interface"
	default y
	---help---
	Support for TCP socket monitoring interface used by native Linux
	tools such as ss. ss is included in iproute2, currently downloadable
	at <http://developer.osdl.org/dev/iproute2>. If you want IPv6 support
	and have selected IPv6 as a module, you need to build this as a
	module too.

	If unsure, say Y.

	config IP_TCPDIAG_IPV6
	def_bool (IP_TCPDIAG=y && IPV6=y) \|\| (IP_TCPDIAG=m && IPV6)

	config TCP_CONG_ADVANCED
	bool "TCP: advanced congestion control"
	---help---
	Support for selection of various TCP congestion control
	modules.

	Nearly all users can safely say no here, and a safe default
	selection will be made (BIC-TCP with new Reno as a fallback).

	If unsure, say N.

	# TCP Reno is builtin (required as fallback)
	menu "TCP congestion control"
	depends on TCP_CONG_ADVANCED

	config TCP_CONG_BIC
	tristate "Binary Increase Congestion (BIC) control"
	default y
	---help---
	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.
	See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/

	config TCP_CONG_WESTWOOD
	tristate "TCP Westwood+"
	default m
	---help---
	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.

	config TCP_CONG_HTCP
	tristate "H-TCP"
	default m
	---help---
	H-TCP is a send-side only modifications of the TCP Reno
	protocol stack that optimizes the performance of TCP
	congestion control for high speed network links. It uses a
	modeswitch to change the alpha and beta parameters of TCP Reno
	based on network conditions and in a way so as to be fair with
	other Reno and H-TCP flows.

	config TCP_CONG_HSTCP
	tristate "High Speed TCP"
	depends on EXPERIMENTAL
	default n
	---help---
	Sally Floyd's High Speed TCP (RFC 3649) congestion control.
	A modification to TCP's congestion control mechanism for use
	with large congestion windows. A table indicates how much to
	increase the congestion window by when an ACK is received.
	For more detail see http://www.icir.org/floyd/hstcp.html

	config TCP_CONG_HYBLA
	tristate "TCP-Hybla congestion control algorithm"
	depends on EXPERIMENTAL
	default n
	---help---
	TCP-Hybla is a sender-side only change that eliminates penalization of
	long-RTT, large-bandwidth connections, like when satellite legs are
	involved, expecially when sharing a common bottleneck with normal
	terrestrial connections.

	config TCP_CONG_VEGAS
	tristate "TCP Vegas"
	depends on EXPERIMENTAL
	default n
	---help---
	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.

	config TCP_CONG_SCALABLE
	tristate "Scalable TCP"
	depends on EXPERIMENTAL
	default n
	---help---
	Scalable TCP is a sender-side only change to TCP which uses a
	MIMD congestion control algorithm which has some nice scaling
	properties, though is known to have fairness issues.
	See http://www-lce.eng.cam.ac.uk/~ctk21/scalable/

	endmenu

	config TCP_CONG_BIC
	tristate
	depends on !TCP_CONG_ADVANCED
	default y

	source "net/ipv4/ipvs/Kconfig"