net/ipv4/Kconfig - third_party/linux - Git at Google


            
            #

            
            # IP configuration

            
            #

            
            config IP_MULTICAST

            
            	bool "IP: multicasting"

            
            	depends on INET

            
            	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"

            
            	depends on INET

            
            	---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.


            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"

            
            	depends on INET

            
            	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"

            
            	depends on INET

            
            	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"

            
            	depends on INET

            
            	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 INET && 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)"

            
            	depends on INET

            
            	---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"

            
            	depends on INET

            
            	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"

            
            	depends on INET

            
            	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"

            
            	depends on INET

            
            	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"

            
            	depends on INET

            
            	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"

            
            	depends on INET

            
            	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)


            source "net/ipv4/ipvs/Kconfig"
	#
	# IP configuration
	#
	config IP_MULTICAST
	bool "IP: multicasting"
	depends on INET
	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"
	depends on INET
	---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.

	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"
	depends on INET
	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"
	depends on INET
	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"
	depends on INET
	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 INET && 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)"
	depends on INET
	---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"
	depends on INET
	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"
	depends on INET
	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"
	depends on INET
	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"
	depends on INET
	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"
	depends on INET
	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)

	source "net/ipv4/ipvs/Kconfig"