net/ipv4/Kconfig

   1 #
   2 # IP configuration
   3 #
   4 config IP_MULTICAST
   5         bool "IP: multicasting"
   6         help
   7           This is code for addressing several networked computers at once,
   8           enlarging your kernel by about 2 KB. You need multicasting if you
   9           intend to participate in the MBONE, a high bandwidth network on top
  10           of the Internet which carries audio and video broadcasts. More
  11           information about the MBONE is on the WWW at
  12           <http://www.savetz.com/mbone/>. For most people, it's safe to say N.
  13
  14 config IP_ADVANCED_ROUTER
  15         bool "IP: advanced router"
  16         ---help---
  17           If you intend to run your Linux box mostly as a router, i.e. as a
  18           computer that forwards and redistributes network packets, say Y; you
  19           will then be presented with several options that allow more precise
  20           control about the routing process.
  21
  22           The answer to this question won't directly affect the kernel:
  23           answering N will just cause the configurator to skip all the
  24           questions about advanced routing.
  25
  26           Note that your box can only act as a router if you enable IP
  27           forwarding in your kernel; you can do that by saying Y to "/proc
  28           file system support" and "Sysctl support" below and executing the
  29           line
  30
  31           echo "1" > /proc/sys/net/ipv4/ip_forward
  32
  33           at boot time after the /proc file system has been mounted.
  34
  35           If you turn on IP forwarding, you should consider the rp_filter, which
  36           automatically rejects incoming packets if the routing table entry
  37           for their source address doesn't match the network interface they're
  38           arriving on. This has security advantages because it prevents the
  39           so-called IP spoofing, however it can pose problems if you use
  40           asymmetric routing (packets from you to a host take a different path
  41           than packets from that host to you) or if you operate a non-routing
  42           host which has several IP addresses on different interfaces. To turn
  43           rp_filter on use:
  44
  45           echo 1 > /proc/sys/net/ipv4/conf/<device>/rp_filter
  46            or
  47           echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
  48
  49           Note that some distributions enable it in startup scripts.
  50           For details about rp_filter strict and loose mode read
  51           <file:Documentation/networking/ip-sysctl.txt>.
  52
  53           If unsure, say N here.
  54
  55 config IP_FIB_TRIE_STATS
  56         bool "FIB TRIE statistics"
  57         depends on IP_ADVANCED_ROUTER
  58         ---help---
  59           Keep track of statistics on structure of FIB TRIE table.
  60           Useful for testing and measuring TRIE performance.
  61
  62 config IP_MULTIPLE_TABLES
  63         bool "IP: policy routing"
  64         depends on IP_ADVANCED_ROUTER
  65         select FIB_RULES
  66         ---help---
  67           Normally, a router decides what to do with a received packet based
  68           solely on the packet's final destination address. If you say Y here,
  69           the Linux router will also be able to take the packet's source
  70           address into account. Furthermore, the TOS (Type-Of-Service) field
  71           of the packet can be used for routing decisions as well.
  72
  73           If you are interested in this, please see the preliminary
  74           documentation at <http://www.compendium.com.ar/policy-routing.txt>
  75           and <ftp://post.tepkom.ru/pub/vol2/Linux/docs/advanced-routing.tex>.
  76           You will need supporting software from
  77           <ftp://ftp.tux.org/pub/net/ip-routing/>.
  78
  79           If unsure, say N.
  80
  81 config IP_ROUTE_MULTIPATH
  82         bool "IP: equal cost multipath"
  83         depends on IP_ADVANCED_ROUTER
  84         help
  85           Normally, the routing tables specify a single action to be taken in
  86           a deterministic manner for a given packet. If you say Y here
  87           however, it becomes possible to attach several actions to a packet
  88           pattern, in effect specifying several alternative paths to travel
  89           for those packets. The router considers all these paths to be of
  90           equal "cost" and chooses one of them in a non-deterministic fashion
  91           if a matching packet arrives.
  92
  93 config IP_ROUTE_VERBOSE
  94         bool "IP: verbose route monitoring"
  95         depends on IP_ADVANCED_ROUTER
  96         help
  97           If you say Y here, which is recommended, then the kernel will print
  98           verbose messages regarding the routing, for example warnings about
  99           received packets which look strange and could be evidence of an
 100           attack or a misconfigured system somewhere. The information is
 101           handled by the klogd daemon which is responsible for kernel messages
 102           ("man klogd").
 103
 104 config IP_ROUTE_CLASSID
 105         bool
 106
 107 config IP_PNP
 108         bool "IP: kernel level autoconfiguration"
 109         help
 110           This enables automatic configuration of IP addresses of devices and
 111           of the routing table during kernel boot, based on either information
 112           supplied on the kernel command line or by BOOTP or RARP protocols.
 113           You need to say Y only for diskless machines requiring network
 114           access to boot (in which case you want to say Y to "Root file system
 115           on NFS" as well), because all other machines configure the network
 116           in their startup scripts.
 117
 118 config IP_PNP_DHCP
 119         bool "IP: DHCP support"
 120         depends on IP_PNP
 121         ---help---
 122           If you want your Linux box to mount its whole root file system (the
 123           one containing the directory /) from some other computer over the
 124           net via NFS and you want the IP address of your computer to be
 125           discovered automatically at boot time using the DHCP protocol (a
 126           special protocol designed for doing this job), say Y here. In case
 127           the boot ROM of your network card was designed for booting Linux and
 128           does DHCP itself, providing all necessary information on the kernel
 129           command line, you can say N here.
 130
 131           If unsure, say Y. Note that if you want to use DHCP, a DHCP server
 132           must be operating on your network.  Read
 133           <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
 134
 135 config IP_PNP_BOOTP
 136         bool "IP: BOOTP support"
 137         depends on IP_PNP
 138         ---help---
 139           If you want your Linux box to mount its whole root file system (the
 140           one containing the directory /) from some other computer over the
 141           net via NFS and you want the IP address of your computer to be
 142           discovered automatically at boot time using the BOOTP protocol (a
 143           special protocol designed for doing this job), say Y here. In case
 144           the boot ROM of your network card was designed for booting Linux and
 145           does BOOTP itself, providing all necessary information on the kernel
 146           command line, you can say N here. If unsure, say Y. Note that if you
 147           want to use BOOTP, a BOOTP server must be operating on your network.
 148           Read <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
 149
 150 config IP_PNP_RARP
 151         bool "IP: RARP support"
 152         depends on IP_PNP
 153         help
 154           If you want your Linux box to mount its whole root file system (the
 155           one containing the directory /) from some other computer over the
 156           net via NFS and you want the IP address of your computer to be
 157           discovered automatically at boot time using the RARP protocol (an
 158           older protocol which is being obsoleted by BOOTP and DHCP), say Y
 159           here. Note that if you want to use RARP, a RARP server must be
 160           operating on your network. Read
 161           <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
 162
 163 config NET_IPIP
 164         tristate "IP: tunneling"
 165         select INET_TUNNEL
 166         select NET_IP_TUNNEL
 167         ---help---
 168           Tunneling means encapsulating data of one protocol type within
 169           another protocol and sending it over a channel that understands the
 170           encapsulating protocol. This particular tunneling driver implements
 171           encapsulation of IP within IP, which sounds kind of pointless, but
 172           can be useful if you want to make your (or some other) machine
 173           appear on a different network than it physically is, or to use
 174           mobile-IP facilities (allowing laptops to seamlessly move between
 175           networks without changing their IP addresses).
 176
 177           Saying Y to this option will produce two modules ( = code which can
 178           be inserted in and removed from the running kernel whenever you
 179           want). Most people won't need this and can say N.
 180
 181 config NET_IPGRE_DEMUX
 182         tristate "IP: GRE demultiplexer"
 183         help
 184          This is helper module to demultiplex GRE packets on GRE version field criteria.
 185          Required by ip_gre and pptp modules.
 186
 187 config NET_IP_TUNNEL
 188         tristate
 189         default n
 190
 191 config NET_IPGRE
 192         tristate "IP: GRE tunnels over IP"
 193         depends on (IPV6 || IPV6=n) && NET_IPGRE_DEMUX
 194         select NET_IP_TUNNEL
 195         help
 196           Tunneling means encapsulating data of one protocol type within
 197           another protocol and sending it over a channel that understands the
 198           encapsulating protocol. This particular tunneling driver implements
 199           GRE (Generic Routing Encapsulation) and at this time allows
 200           encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure.
 201           This driver is useful if the other endpoint is a Cisco router: Cisco
 202           likes GRE much better than the other Linux tunneling driver ("IP
 203           tunneling" above). In addition, GRE allows multicast redistribution
 204           through the tunnel.
 205
 206 config NET_IPGRE_BROADCAST
 207         bool "IP: broadcast GRE over IP"
 208         depends on IP_MULTICAST && NET_IPGRE
 209         help
 210           One application of GRE/IP is to construct a broadcast WAN (Wide Area
 211           Network), which looks like a normal Ethernet LAN (Local Area
 212           Network), but can be distributed all over the Internet. If you want
 213           to do that, say Y here and to "IP multicast routing" below.
 214
 215 config IP_MROUTE
 216         bool "IP: multicast routing"
 217         depends on IP_MULTICAST
 218         help
 219           This is used if you want your machine to act as a router for IP
 220           packets that have several destination addresses. It is needed on the
 221           MBONE, a high bandwidth network on top of the Internet which carries
 222           audio and video broadcasts. In order to do that, you would most
 223           likely run the program mrouted. If you haven't heard about it, you
 224           don't need it.
 225
 226 config IP_MROUTE_MULTIPLE_TABLES
 227         bool "IP: multicast policy routing"
 228         depends on IP_MROUTE && IP_ADVANCED_ROUTER
 229         select FIB_RULES
 230         help
 231           Normally, a multicast router runs a userspace daemon and decides
 232           what to do with a multicast packet based on the source and
 233           destination addresses. If you say Y here, the multicast router
 234           will also be able to take interfaces and packet marks into
 235           account and run multiple instances of userspace daemons
 236           simultaneously, each one handling a single table.
 237
 238           If unsure, say N.
 239
 240 config IP_PIMSM_V1
 241         bool "IP: PIM-SM version 1 support"
 242         depends on IP_MROUTE
 243         help
 244           Kernel side support for Sparse Mode PIM (Protocol Independent
 245           Multicast) version 1. This multicast routing protocol is used widely
 246           because Cisco supports it. You need special software to use it
 247           (pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
 248           information about PIM.
 249
 250           Say Y if you want to use PIM-SM v1. Note that you can say N here if
 251           you just want to use Dense Mode PIM.
 252
 253 config IP_PIMSM_V2
 254         bool "IP: PIM-SM version 2 support"
 255         depends on IP_MROUTE
 256         help
 257           Kernel side support for Sparse Mode PIM version 2. In order to use
 258           this, you need an experimental routing daemon supporting it (pimd or
 259           gated-5). This routing protocol is not used widely, so say N unless
 260           you want to play with it.
 261
 262 config SYN_COOKIES
 263         bool "IP: TCP syncookie support"
 264         ---help---
 265           Normal TCP/IP networking is open to an attack known as "SYN
 266           flooding". This denial-of-service attack prevents legitimate remote
 267           users from being able to connect to your computer during an ongoing
 268           attack and requires very little work from the attacker, who can
 269           operate from anywhere on the Internet.
 270
 271           SYN cookies provide protection against this type of attack. If you
 272           say Y here, the TCP/IP stack will use a cryptographic challenge
 273           protocol known as "SYN cookies" to enable legitimate users to
 274           continue to connect, even when your machine is under attack. There
 275           is no need for the legitimate users to change their TCP/IP software;
 276           SYN cookies work transparently to them. For technical information
 277           about SYN cookies, check out <http://cr.yp.to/syncookies.html>.
 278
 279           If you are SYN flooded, the source address reported by the kernel is
 280           likely to have been forged by the attacker; it is only reported as
 281           an aid in tracing the packets to their actual source and should not
 282           be taken as absolute truth.
 283
 284           SYN cookies may prevent correct error reporting on clients when the
 285           server is really overloaded. If this happens frequently better turn
 286           them off.
 287
 288           If you say Y here, you can disable SYN cookies at run time by
 289           saying Y to "/proc file system support" and
 290           "Sysctl support" below and executing the command
 291
 292           echo 0 > /proc/sys/net/ipv4/tcp_syncookies
 293
 294           after the /proc file system has been mounted.
 295
 296           If unsure, say N.
 297
 298 config NET_IPVTI
 299         tristate "Virtual (secure) IP: tunneling"
 300         select INET_TUNNEL
 301         select NET_IP_TUNNEL
 302         depends on INET_XFRM_MODE_TUNNEL
 303         ---help---
 304           Tunneling means encapsulating data of one protocol type within
 305           another protocol and sending it over a channel that understands the
 306           encapsulating protocol. This can be used with xfrm mode tunnel to give
 307           the notion of a secure tunnel for IPSEC and then use routing protocol
 308           on top.
 309
 310 config NET_UDP_TUNNEL
 311         tristate
 312         select NET_IP_TUNNEL
 313         default n
 314
 315 config NET_FOU
 316         tristate "IP: Foo (IP protocols) over UDP"
 317         select XFRM
 318         select NET_UDP_TUNNEL
 319         ---help---
 320           Foo over UDP allows any IP protocol to be directly encapsulated
 321           over UDP include tunnels (IPIP, GRE, SIT). By encapsulating in UDP
 322           network mechanisms and optimizations for UDP (such as ECMP
 323           and RSS) can be leveraged to provide better service.
 324
 325 config NET_FOU_IP_TUNNELS
 326         bool "IP: FOU encapsulation of IP tunnels"
 327         depends on NET_IPIP || NET_IPGRE || IPV6_SIT
 328         select NET_FOU
 329         ---help---
 330           Allow configuration of FOU or GUE encapsulation for IP tunnels.
 331           When this option is enabled IP tunnels can be configured to use
 332           FOU or GUE encapsulation.
 333
 334 config INET_AH
 335         tristate "IP: AH transformation"
 336         select XFRM_ALGO
 337         select CRYPTO
 338         select CRYPTO_HMAC
 339         select CRYPTO_MD5
 340         select CRYPTO_SHA1
 341         ---help---
 342           Support for IPsec AH.
 343
 344           If unsure, say Y.
 345
 346 config INET_ESP
 347         tristate "IP: ESP transformation"
 348         select XFRM_ALGO
 349         select CRYPTO
 350         select CRYPTO_AUTHENC
 351         select CRYPTO_HMAC
 352         select CRYPTO_MD5
 353         select CRYPTO_CBC
 354         select CRYPTO_SHA1
 355         select CRYPTO_DES
 356         ---help---
 357           Support for IPsec ESP.
 358
 359           If unsure, say Y.
 360
 361 config INET_IPCOMP
 362         tristate "IP: IPComp transformation"
 363         select INET_XFRM_TUNNEL
 364         select XFRM_IPCOMP
 365         ---help---
 366           Support for IP Payload Compression Protocol (IPComp) (RFC3173),
 367           typically needed for IPsec.
 368
 369           If unsure, say Y.
 370
 371 config INET_XFRM_TUNNEL
 372         tristate
 373         select INET_TUNNEL
 374         default n
 375
 376 config INET_TUNNEL
 377         tristate
 378         default n
 379
 380 config INET_XFRM_MODE_TRANSPORT
 381         tristate "IP: IPsec transport mode"
 382         default y
 383         select XFRM
 384         ---help---
 385           Support for IPsec transport mode.
 386
 387           If unsure, say Y.
 388
 389 config INET_XFRM_MODE_TUNNEL
 390         tristate "IP: IPsec tunnel mode"
 391         default y
 392         select XFRM
 393         ---help---
 394           Support for IPsec tunnel mode.
 395
 396           If unsure, say Y.
 397
 398 config INET_XFRM_MODE_BEET
 399         tristate "IP: IPsec BEET mode"
 400         default y
 401         select XFRM
 402         ---help---
 403           Support for IPsec BEET mode.
 404
 405           If unsure, say Y.
 406
 407 config INET_LRO
 408         tristate "Large Receive Offload (ipv4/tcp)"
 409         default y
 410         ---help---
 411           Support for Large Receive Offload (ipv4/tcp).
 412
 413           If unsure, say Y.
 414
 415 config INET_DIAG
 416         tristate "INET: socket monitoring interface"
 417         default y
 418         ---help---
 419           Support for INET (TCP, DCCP, etc) socket monitoring interface used by
 420           native Linux tools such as ss. ss is included in iproute2, currently
 421           downloadable at:
 422
 423             http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2
 424
 425           If unsure, say Y.
 426
 427 config INET_TCP_DIAG
 428         depends on INET_DIAG
 429         def_tristate INET_DIAG
 430
 431 config INET_UDP_DIAG
 432         tristate "UDP: socket monitoring interface"
 433         depends on INET_DIAG && (IPV6 || IPV6=n)
 434         default n
 435         ---help---
 436           Support for UDP socket monitoring interface used by the ss tool.
 437           If unsure, say Y.
 438
 439 config INET_DIAG_DESTROY
 440         bool "INET: allow privileged process to administratively close sockets"
 441         depends on INET_DIAG
 442         default n
 443         ---help---
 444           Provides a SOCK_DESTROY operation that allows privileged processes
 445           (e.g., a connection manager or a network administration tool such as
 446           ss) to close sockets opened by other processes. Closing a socket in
 447           this way interrupts any blocking read/write/connect operations on
 448           the socket and causes future socket calls to behave as if the socket
 449           had been disconnected.
 450           If unsure, say N.
 451
 452 menuconfig TCP_CONG_ADVANCED
 453         bool "TCP: advanced congestion control"
 454         ---help---
 455           Support for selection of various TCP congestion control
 456           modules.
 457
 458           Nearly all users can safely say no here, and a safe default
 459           selection will be made (CUBIC with new Reno as a fallback).
 460
 461           If unsure, say N.
 462
 463 if TCP_CONG_ADVANCED
 464
 465 config TCP_CONG_BIC
 466         tristate "Binary Increase Congestion (BIC) control"
 467         default m
 468         ---help---
 469         BIC-TCP is a sender-side only change that ensures a linear RTT
 470         fairness under large windows while offering both scalability and
 471         bounded TCP-friendliness. The protocol combines two schemes
 472         called additive increase and binary search increase. When the
 473         congestion window is large, additive increase with a large
 474         increment ensures linear RTT fairness as well as good
 475         scalability. Under small congestion windows, binary search
 476         increase provides TCP friendliness.
 477         See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
 478
 479 config TCP_CONG_CUBIC
 480         tristate "CUBIC TCP"
 481         default y
 482         ---help---
 483         This is version 2.0 of BIC-TCP which uses a cubic growth function
 484         among other techniques.
 485         See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
 486
 487 config TCP_CONG_WESTWOOD
 488         tristate "TCP Westwood+"
 489         default m
 490         ---help---
 491         TCP Westwood+ is a sender-side only modification of the TCP Reno
 492         protocol stack that optimizes the performance of TCP congestion
 493         control. It is based on end-to-end bandwidth estimation to set
 494         congestion window and slow start threshold after a congestion
 495         episode. Using this estimation, TCP Westwood+ adaptively sets a
 496         slow start threshold and a congestion window which takes into
 497         account the bandwidth used  at the time congestion is experienced.
 498         TCP Westwood+ significantly increases fairness wrt TCP Reno in
 499         wired networks and throughput over wireless links.
 500
 501 config TCP_CONG_HTCP
 502         tristate "H-TCP"
 503         default m
 504         ---help---
 505         H-TCP is a send-side only modifications of the TCP Reno
 506         protocol stack that optimizes the performance of TCP
 507         congestion control for high speed network links. It uses a
 508         modeswitch to change the alpha and beta parameters of TCP Reno
 509         based on network conditions and in a way so as to be fair with
 510         other Reno and H-TCP flows.
 511
 512 config TCP_CONG_HSTCP
 513         tristate "High Speed TCP"
 514         default n
 515         ---help---
 516         Sally Floyd's High Speed TCP (RFC 3649) congestion control.
 517         A modification to TCP's congestion control mechanism for use
 518         with large congestion windows. A table indicates how much to
 519         increase the congestion window by when an ACK is received.
 520         For more detail see http://www.icir.org/floyd/hstcp.html
 521
 522 config TCP_CONG_HYBLA
 523         tristate "TCP-Hybla congestion control algorithm"
 524         default n
 525         ---help---
 526         TCP-Hybla is a sender-side only change that eliminates penalization of
 527         long-RTT, large-bandwidth connections, like when satellite legs are
 528         involved, especially when sharing a common bottleneck with normal
 529         terrestrial connections.
 530
 531 config TCP_CONG_VEGAS
 532         tristate "TCP Vegas"
 533         default n
 534         ---help---
 535         TCP Vegas is a sender-side only change to TCP that anticipates
 536         the onset of congestion by estimating the bandwidth. TCP Vegas
 537         adjusts the sending rate by modifying the congestion
 538         window. TCP Vegas should provide less packet loss, but it is
 539         not as aggressive as TCP Reno.
 540
 541 config TCP_CONG_SCALABLE
 542         tristate "Scalable TCP"
 543         default n
 544         ---help---
 545         Scalable TCP is a sender-side only change to TCP which uses a
 546         MIMD congestion control algorithm which has some nice scaling
 547         properties, though is known to have fairness issues.
 548         See http://www.deneholme.net/tom/scalable/
 549
 550 config TCP_CONG_LP
 551         tristate "TCP Low Priority"
 552         default n
 553         ---help---
 554         TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
 555         to utilize only the excess network bandwidth as compared to the
 556         ``fair share`` of bandwidth as targeted by TCP.
 557         See http://www-ece.rice.edu/networks/TCP-LP/
 558
 559 config TCP_CONG_VENO
 560         tristate "TCP Veno"
 561         default n
 562         ---help---
 563         TCP Veno is a sender-side only enhancement of TCP to obtain better
 564         throughput over wireless networks. TCP Veno makes use of state
 565         distinguishing to circumvent the difficult judgment of the packet loss
 566         type. TCP Veno cuts down less congestion window in response to random
 567         loss packets.
 568         See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
 569
 570 config TCP_CONG_YEAH
 571         tristate "YeAH TCP"
 572         select TCP_CONG_VEGAS
 573         default n
 574         ---help---
 575         YeAH-TCP is a sender-side high-speed enabled TCP congestion control
 576         algorithm, which uses a mixed loss/delay approach to compute the
 577         congestion window. It's design goals target high efficiency,
 578         internal, RTT and Reno fairness, resilience to link loss while
 579         keeping network elements load as low as possible.
 580
 581         For further details look here:
 582           http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
 583
 584 config TCP_CONG_ILLINOIS
 585         tristate "TCP Illinois"
 586         default n
 587         ---help---
 588         TCP-Illinois is a sender-side modification of TCP Reno for
 589         high speed long delay links. It uses round-trip-time to
 590         adjust the alpha and beta parameters to achieve a higher average
 591         throughput and maintain fairness.
 592
 593         For further details see:
 594           http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
 595
 596 config TCP_CONG_DCTCP
 597         tristate "DataCenter TCP (DCTCP)"
 598         default n
 599         ---help---
 600         DCTCP leverages Explicit Congestion Notification (ECN) in the network to
 601         provide multi-bit feedback to the end hosts. It is designed to provide:
 602
 603         - High burst tolerance (incast due to partition/aggregate),
 604         - Low latency (short flows, queries),
 605         - High throughput (continuous data updates, large file transfers) with
 606           commodity, shallow-buffered switches.
 607
 608         All switches in the data center network running DCTCP must support
 609         ECN marking and be configured for marking when reaching defined switch
 610         buffer thresholds. The default ECN marking threshold heuristic for
 611         DCTCP on switches is 20 packets (30KB) at 1Gbps, and 65 packets
 612         (~100KB) at 10Gbps, but might need further careful tweaking.
 613
 614         For further details see:
 615           http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
 616
 617 config TCP_CONG_CDG
 618         tristate "CAIA Delay-Gradient (CDG)"
 619         default n
 620         ---help---
 621         CAIA Delay-Gradient (CDG) is a TCP congestion control that modifies
 622         the TCP sender in order to:
 623
 624           o Use the delay gradient as a congestion signal.
 625           o Back off with an average probability that is independent of the RTT.
 626           o Coexist with flows that use loss-based congestion control.
 627           o Tolerate packet loss unrelated to congestion.
 628
 629         For further details see:
 630           D.A. Hayes and G. Armitage. "Revisiting TCP congestion control using
 631           delay gradients." In Networking 2011. Preprint: http://goo.gl/No3vdg
 632
 633 choice
 634         prompt "Default TCP congestion control"
 635         default DEFAULT_CUBIC
 636         help
 637           Select the TCP congestion control that will be used by default
 638           for all connections.
 639
 640         config DEFAULT_BIC
 641                 bool "Bic" if TCP_CONG_BIC=y
 642
 643         config DEFAULT_CUBIC
 644                 bool "Cubic" if TCP_CONG_CUBIC=y
 645
 646         config DEFAULT_HTCP
 647                 bool "Htcp" if TCP_CONG_HTCP=y
 648
 649         config DEFAULT_HYBLA
 650                 bool "Hybla" if TCP_CONG_HYBLA=y
 651
 652         config DEFAULT_VEGAS
 653                 bool "Vegas" if TCP_CONG_VEGAS=y
 654
 655         config DEFAULT_VENO
 656                 bool "Veno" if TCP_CONG_VENO=y
 657
 658         config DEFAULT_WESTWOOD
 659                 bool "Westwood" if TCP_CONG_WESTWOOD=y
 660
 661         config DEFAULT_DCTCP
 662                 bool "DCTCP" if TCP_CONG_DCTCP=y
 663
 664         config DEFAULT_CDG
 665                 bool "CDG" if TCP_CONG_CDG=y
 666
 667         config DEFAULT_RENO
 668                 bool "Reno"
 669 endchoice
 670
 671 endif
 672
 673 config TCP_CONG_CUBIC
 674         tristate
 675         depends on !TCP_CONG_ADVANCED
 676         default y
 677
 678 config DEFAULT_TCP_CONG
 679         string
 680         default "bic" if DEFAULT_BIC
 681         default "cubic" if DEFAULT_CUBIC
 682         default "htcp" if DEFAULT_HTCP
 683         default "hybla" if DEFAULT_HYBLA
 684         default "vegas" if DEFAULT_VEGAS
 685         default "westwood" if DEFAULT_WESTWOOD
 686         default "veno" if DEFAULT_VENO
 687         default "reno" if DEFAULT_RENO
 688         default "dctcp" if DEFAULT_DCTCP
 689         default "cdg" if DEFAULT_CDG
 690         default "cubic"
 691
 692 config TCP_MD5SIG
 693         bool "TCP: MD5 Signature Option support (RFC2385)"
 694         select CRYPTO
 695         select CRYPTO_MD5
 696         ---help---
 697           RFC2385 specifies a method of giving MD5 protection to TCP sessions.
 698           Its main (only?) use is to protect BGP sessions between core routers
 699           on the Internet.
 700
 701           If unsure, say N.