[NET]: Store skb->timestamp as offset to a base timestamp

[linux-2.6] / net / ipv4 / 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 ASK_IP_FIB_HASH

config ASK_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

config IP_FIB_HASH
        def_bool ASK_IP_FIB_HASH || !IP_ADVANCED_ROUTER

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"
        ---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"
        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 INET_DIAG
        tristate "INET: socket monitoring interface"
        default y
        ---help---
          Support for INET (TCP, DCCP, etc) 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 unsure, say Y.

config INET_TCP_DIAG
        depends on INET_DIAG
        def_tristate INET_DIAG

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"