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