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 ---help--- 170 Tunneling means encapsulating data of one protocol type within 171 another protocol and sending it over a channel that understands the 172 encapsulating protocol. This particular tunneling driver implements 173 encapsulation of IP within IP, which sounds kind of pointless, but 174 can be useful if you want to make your (or some other) machine 175 appear on a different network than it physically is, or to use 176 mobile-IP facilities (allowing laptops to seamlessly move between 177 networks without changing their IP addresses). 178 179 Saying Y to this option will produce two modules ( = code which can 180 be inserted in and removed from the running kernel whenever you 181 want). Most people won't need this and can say N. 182 183config NET_IPGRE_DEMUX 184 tristate "IP: GRE demultiplexer" 185 help 186 This is helper module to demultiplex GRE packets on GRE version field criteria. 187 Required by ip_gre and pptp modules. 188 189config NET_IPGRE 190 tristate "IP: GRE tunnels over IP" 191 depends on (IPV6 || IPV6=n) && NET_IPGRE_DEMUX 192 help 193 Tunneling means encapsulating data of one protocol type within 194 another protocol and sending it over a channel that understands the 195 encapsulating protocol. This particular tunneling driver implements 196 GRE (Generic Routing Encapsulation) and at this time allows 197 encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure. 198 This driver is useful if the other endpoint is a Cisco router: Cisco 199 likes GRE much better than the other Linux tunneling driver ("IP 200 tunneling" above). In addition, GRE allows multicast redistribution 201 through the tunnel. 202 203config NET_IPGRE_BROADCAST 204 bool "IP: broadcast GRE over IP" 205 depends on IP_MULTICAST && NET_IPGRE 206 help 207 One application of GRE/IP is to construct a broadcast WAN (Wide Area 208 Network), which looks like a normal Ethernet LAN (Local Area 209 Network), but can be distributed all over the Internet. If you want 210 to do that, say Y here and to "IP multicast routing" below. 211 212config IP_MROUTE 213 bool "IP: multicast routing" 214 depends on IP_MULTICAST 215 help 216 This is used if you want your machine to act as a router for IP 217 packets that have several destination addresses. It is needed on the 218 MBONE, a high bandwidth network on top of the Internet which carries 219 audio and video broadcasts. In order to do that, you would most 220 likely run the program mrouted. Information about the multicast 221 capabilities of the various network cards is contained in 222 <file:Documentation/networking/multicast.txt>. If you haven't heard 223 about it, you don't need it. 224 225config IP_MROUTE_MULTIPLE_TABLES 226 bool "IP: multicast policy routing" 227 depends on IP_MROUTE && IP_ADVANCED_ROUTER 228 select FIB_RULES 229 help 230 Normally, a multicast router runs a userspace daemon and decides 231 what to do with a multicast packet based on the source and 232 destination addresses. If you say Y here, the multicast router 233 will also be able to take interfaces and packet marks into 234 account and run multiple instances of userspace daemons 235 simultaneously, each one handling a single table. 236 237 If unsure, say N. 238 239config IP_PIMSM_V1 240 bool "IP: PIM-SM version 1 support" 241 depends on IP_MROUTE 242 help 243 Kernel side support for Sparse Mode PIM (Protocol Independent 244 Multicast) version 1. This multicast routing protocol is used widely 245 because Cisco supports it. You need special software to use it 246 (pimd-v1). Please see <http://netweb.usc.edu/pim/> for more 247 information about PIM. 248 249 Say Y if you want to use PIM-SM v1. Note that you can say N here if 250 you just want to use Dense Mode PIM. 251 252config IP_PIMSM_V2 253 bool "IP: PIM-SM version 2 support" 254 depends on IP_MROUTE 255 help 256 Kernel side support for Sparse Mode PIM version 2. In order to use 257 this, you need an experimental routing daemon supporting it (pimd or 258 gated-5). This routing protocol is not used widely, so say N unless 259 you want to play with it. 260 261config ARPD 262 bool "IP: ARP daemon support" 263 ---help--- 264 The kernel maintains an internal cache which maps IP addresses to 265 hardware addresses on the local network, so that Ethernet/Token Ring/ 266 etc. frames are sent to the proper address on the physical networking 267 layer. Normally, kernel uses the ARP protocol to resolve these 268 mappings. 269 270 Saying Y here adds support to have an user space daemon to do this 271 resolution instead. This is useful for implementing an alternate 272 address resolution protocol (e.g. NHRP on mGRE tunnels) and also for 273 testing purposes. 274 275 If unsure, say N. 276 277config SYN_COOKIES 278 bool "IP: TCP syncookie support" 279 ---help--- 280 Normal TCP/IP networking is open to an attack known as "SYN 281 flooding". This denial-of-service attack prevents legitimate remote 282 users from being able to connect to your computer during an ongoing 283 attack and requires very little work from the attacker, who can 284 operate from anywhere on the Internet. 285 286 SYN cookies provide protection against this type of attack. If you 287 say Y here, the TCP/IP stack will use a cryptographic challenge 288 protocol known as "SYN cookies" to enable legitimate users to 289 continue to connect, even when your machine is under attack. There 290 is no need for the legitimate users to change their TCP/IP software; 291 SYN cookies work transparently to them. For technical information 292 about SYN cookies, check out <http://cr.yp.to/syncookies.html>. 293 294 If you are SYN flooded, the source address reported by the kernel is 295 likely to have been forged by the attacker; it is only reported as 296 an aid in tracing the packets to their actual source and should not 297 be taken as absolute truth. 298 299 SYN cookies may prevent correct error reporting on clients when the 300 server is really overloaded. If this happens frequently better turn 301 them off. 302 303 If you say Y here, you can disable SYN cookies at run time by 304 saying Y to "/proc file system support" and 305 "Sysctl support" below and executing the command 306 307 echo 0 > /proc/sys/net/ipv4/tcp_syncookies 308 309 after the /proc file system has been mounted. 310 311 If unsure, say N. 312 313config INET_AH 314 tristate "IP: AH transformation" 315 select XFRM 316 select CRYPTO 317 select CRYPTO_HMAC 318 select CRYPTO_MD5 319 select CRYPTO_SHA1 320 ---help--- 321 Support for IPsec AH. 322 323 If unsure, say Y. 324 325config INET_ESP 326 tristate "IP: ESP transformation" 327 select XFRM 328 select CRYPTO 329 select CRYPTO_AUTHENC 330 select CRYPTO_HMAC 331 select CRYPTO_MD5 332 select CRYPTO_CBC 333 select CRYPTO_SHA1 334 select CRYPTO_DES 335 ---help--- 336 Support for IPsec ESP. 337 338 If unsure, say Y. 339 340config INET_IPCOMP 341 tristate "IP: IPComp transformation" 342 select INET_XFRM_TUNNEL 343 select XFRM_IPCOMP 344 ---help--- 345 Support for IP Payload Compression Protocol (IPComp) (RFC3173), 346 typically needed for IPsec. 347 348 If unsure, say Y. 349 350config INET_XFRM_TUNNEL 351 tristate 352 select INET_TUNNEL 353 default n 354 355config INET_TUNNEL 356 tristate 357 default n 358 359config INET_XFRM_MODE_TRANSPORT 360 tristate "IP: IPsec transport mode" 361 default y 362 select XFRM 363 ---help--- 364 Support for IPsec transport mode. 365 366 If unsure, say Y. 367 368config INET_XFRM_MODE_TUNNEL 369 tristate "IP: IPsec tunnel mode" 370 default y 371 select XFRM 372 ---help--- 373 Support for IPsec tunnel mode. 374 375 If unsure, say Y. 376 377config INET_XFRM_MODE_BEET 378 tristate "IP: IPsec BEET mode" 379 default y 380 select XFRM 381 ---help--- 382 Support for IPsec BEET mode. 383 384 If unsure, say Y. 385 386config INET_LRO 387 tristate "Large Receive Offload (ipv4/tcp)" 388 default y 389 ---help--- 390 Support for Large Receive Offload (ipv4/tcp). 391 392 If unsure, say Y. 393 394config INET_DIAG 395 tristate "INET: socket monitoring interface" 396 default y 397 ---help--- 398 Support for INET (TCP, DCCP, etc) socket monitoring interface used by 399 native Linux tools such as ss. ss is included in iproute2, currently 400 downloadable at: 401 402 http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2 403 404 If unsure, say Y. 405 406config INET_TCP_DIAG 407 depends on INET_DIAG 408 def_tristate INET_DIAG 409 410menuconfig TCP_CONG_ADVANCED 411 bool "TCP: advanced congestion control" 412 ---help--- 413 Support for selection of various TCP congestion control 414 modules. 415 416 Nearly all users can safely say no here, and a safe default 417 selection will be made (CUBIC with new Reno as a fallback). 418 419 If unsure, say N. 420 421if TCP_CONG_ADVANCED 422 423config TCP_CONG_BIC 424 tristate "Binary Increase Congestion (BIC) control" 425 default m 426 ---help--- 427 BIC-TCP is a sender-side only change that ensures a linear RTT 428 fairness under large windows while offering both scalability and 429 bounded TCP-friendliness. The protocol combines two schemes 430 called additive increase and binary search increase. When the 431 congestion window is large, additive increase with a large 432 increment ensures linear RTT fairness as well as good 433 scalability. Under small congestion windows, binary search 434 increase provides TCP friendliness. 435 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/ 436 437config TCP_CONG_CUBIC 438 tristate "CUBIC TCP" 439 default y 440 ---help--- 441 This is version 2.0 of BIC-TCP which uses a cubic growth function 442 among other techniques. 443 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf 444 445config TCP_CONG_WESTWOOD 446 tristate "TCP Westwood+" 447 default m 448 ---help--- 449 TCP Westwood+ is a sender-side only modification of the TCP Reno 450 protocol stack that optimizes the performance of TCP congestion 451 control. It is based on end-to-end bandwidth estimation to set 452 congestion window and slow start threshold after a congestion 453 episode. Using this estimation, TCP Westwood+ adaptively sets a 454 slow start threshold and a congestion window which takes into 455 account the bandwidth used at the time congestion is experienced. 456 TCP Westwood+ significantly increases fairness wrt TCP Reno in 457 wired networks and throughput over wireless links. 458 459config TCP_CONG_HTCP 460 tristate "H-TCP" 461 default m 462 ---help--- 463 H-TCP is a send-side only modifications of the TCP Reno 464 protocol stack that optimizes the performance of TCP 465 congestion control for high speed network links. It uses a 466 modeswitch to change the alpha and beta parameters of TCP Reno 467 based on network conditions and in a way so as to be fair with 468 other Reno and H-TCP flows. 469 470config TCP_CONG_HSTCP 471 tristate "High Speed TCP" 472 depends on EXPERIMENTAL 473 default n 474 ---help--- 475 Sally Floyd's High Speed TCP (RFC 3649) congestion control. 476 A modification to TCP's congestion control mechanism for use 477 with large congestion windows. A table indicates how much to 478 increase the congestion window by when an ACK is received. 479 For more detail see http://www.icir.org/floyd/hstcp.html 480 481config TCP_CONG_HYBLA 482 tristate "TCP-Hybla congestion control algorithm" 483 depends on EXPERIMENTAL 484 default n 485 ---help--- 486 TCP-Hybla is a sender-side only change that eliminates penalization of 487 long-RTT, large-bandwidth connections, like when satellite legs are 488 involved, especially when sharing a common bottleneck with normal 489 terrestrial connections. 490 491config TCP_CONG_VEGAS 492 tristate "TCP Vegas" 493 depends on EXPERIMENTAL 494 default n 495 ---help--- 496 TCP Vegas is a sender-side only change to TCP that anticipates 497 the onset of congestion by estimating the bandwidth. TCP Vegas 498 adjusts the sending rate by modifying the congestion 499 window. TCP Vegas should provide less packet loss, but it is 500 not as aggressive as TCP Reno. 501 502config TCP_CONG_SCALABLE 503 tristate "Scalable TCP" 504 depends on EXPERIMENTAL 505 default n 506 ---help--- 507 Scalable TCP is a sender-side only change to TCP which uses a 508 MIMD congestion control algorithm which has some nice scaling 509 properties, though is known to have fairness issues. 510 See http://www.deneholme.net/tom/scalable/ 511 512config TCP_CONG_LP 513 tristate "TCP Low Priority" 514 depends on EXPERIMENTAL 515 default n 516 ---help--- 517 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is 518 to utilize only the excess network bandwidth as compared to the 519 ``fair share`` of bandwidth as targeted by TCP. 520 See http://www-ece.rice.edu/networks/TCP-LP/ 521 522config TCP_CONG_VENO 523 tristate "TCP Veno" 524 depends on EXPERIMENTAL 525 default n 526 ---help--- 527 TCP Veno is a sender-side only enhancement of TCP to obtain better 528 throughput over wireless networks. TCP Veno makes use of state 529 distinguishing to circumvent the difficult judgment of the packet loss 530 type. TCP Veno cuts down less congestion window in response to random 531 loss packets. 532 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186> 533 534config TCP_CONG_YEAH 535 tristate "YeAH TCP" 536 depends on EXPERIMENTAL 537 select TCP_CONG_VEGAS 538 default n 539 ---help--- 540 YeAH-TCP is a sender-side high-speed enabled TCP congestion control 541 algorithm, which uses a mixed loss/delay approach to compute the 542 congestion window. It's design goals target high efficiency, 543 internal, RTT and Reno fairness, resilience to link loss while 544 keeping network elements load as low as possible. 545 546 For further details look here: 547 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf 548 549config TCP_CONG_ILLINOIS 550 tristate "TCP Illinois" 551 depends on EXPERIMENTAL 552 default n 553 ---help--- 554 TCP-Illinois is a sender-side modification of TCP Reno for 555 high speed long delay links. It uses round-trip-time to 556 adjust the alpha and beta parameters to achieve a higher average 557 throughput and maintain fairness. 558 559 For further details see: 560 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html 561 562choice 563 prompt "Default TCP congestion control" 564 default DEFAULT_CUBIC 565 help 566 Select the TCP congestion control that will be used by default 567 for all connections. 568 569 config DEFAULT_BIC 570 bool "Bic" if TCP_CONG_BIC=y 571 572 config DEFAULT_CUBIC 573 bool "Cubic" if TCP_CONG_CUBIC=y 574 575 config DEFAULT_HTCP 576 bool "Htcp" if TCP_CONG_HTCP=y 577 578 config DEFAULT_HYBLA 579 bool "Hybla" if TCP_CONG_HYBLA=y 580 581 config DEFAULT_VEGAS 582 bool "Vegas" if TCP_CONG_VEGAS=y 583 584 config DEFAULT_VENO 585 bool "Veno" if TCP_CONG_VENO=y 586 587 config DEFAULT_WESTWOOD 588 bool "Westwood" if TCP_CONG_WESTWOOD=y 589 590 config DEFAULT_RENO 591 bool "Reno" 592 593endchoice 594 595endif 596 597config TCP_CONG_CUBIC 598 tristate 599 depends on !TCP_CONG_ADVANCED 600 default y 601 602config DEFAULT_TCP_CONG 603 string 604 default "bic" if DEFAULT_BIC 605 default "cubic" if DEFAULT_CUBIC 606 default "htcp" if DEFAULT_HTCP 607 default "hybla" if DEFAULT_HYBLA 608 default "vegas" if DEFAULT_VEGAS 609 default "westwood" if DEFAULT_WESTWOOD 610 default "veno" if DEFAULT_VENO 611 default "reno" if DEFAULT_RENO 612 default "cubic" 613 614config TCP_MD5SIG 615 bool "TCP: MD5 Signature Option support (RFC2385) (EXPERIMENTAL)" 616 depends on EXPERIMENTAL 617 select CRYPTO 618 select CRYPTO_MD5 619 ---help--- 620 RFC2385 specifies a method of giving MD5 protection to TCP sessions. 621 Its main (only?) use is to protect BGP sessions between core routers 622 on the Internet. 623 624 If unsure, say N. 625