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 266 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 NET_IPVTI 314 tristate "Virtual (secure) IP: tunneling" 315 select INET_TUNNEL 316 depends on INET_XFRM_MODE_TUNNEL 317 ---help--- 318 Tunneling means encapsulating data of one protocol type within 319 another protocol and sending it over a channel that understands the 320 encapsulating protocol. This can be used with xfrm mode tunnel to give 321 the notion of a secure tunnel for IPSEC and then use routing protocol 322 on top. 323 324config INET_AH 325 tristate "IP: AH transformation" 326 select XFRM_ALGO 327 select CRYPTO 328 select CRYPTO_HMAC 329 select CRYPTO_MD5 330 select CRYPTO_SHA1 331 ---help--- 332 Support for IPsec AH. 333 334 If unsure, say Y. 335 336config INET_ESP 337 tristate "IP: ESP transformation" 338 select XFRM_ALGO 339 select CRYPTO 340 select CRYPTO_AUTHENC 341 select CRYPTO_HMAC 342 select CRYPTO_MD5 343 select CRYPTO_CBC 344 select CRYPTO_SHA1 345 select CRYPTO_DES 346 ---help--- 347 Support for IPsec ESP. 348 349 If unsure, say Y. 350 351config INET_IPCOMP 352 tristate "IP: IPComp transformation" 353 select INET_XFRM_TUNNEL 354 select XFRM_IPCOMP 355 ---help--- 356 Support for IP Payload Compression Protocol (IPComp) (RFC3173), 357 typically needed for IPsec. 358 359 If unsure, say Y. 360 361config INET_XFRM_TUNNEL 362 tristate 363 select INET_TUNNEL 364 default n 365 366config INET_TUNNEL 367 tristate 368 default n 369 370config INET_XFRM_MODE_TRANSPORT 371 tristate "IP: IPsec transport mode" 372 default y 373 select XFRM 374 ---help--- 375 Support for IPsec transport mode. 376 377 If unsure, say Y. 378 379config INET_XFRM_MODE_TUNNEL 380 tristate "IP: IPsec tunnel mode" 381 default y 382 select XFRM 383 ---help--- 384 Support for IPsec tunnel mode. 385 386 If unsure, say Y. 387 388config INET_XFRM_MODE_BEET 389 tristate "IP: IPsec BEET mode" 390 default y 391 select XFRM 392 ---help--- 393 Support for IPsec BEET mode. 394 395 If unsure, say Y. 396 397config INET_LRO 398 tristate "Large Receive Offload (ipv4/tcp)" 399 default y 400 ---help--- 401 Support for Large Receive Offload (ipv4/tcp). 402 403 If unsure, say Y. 404 405config INET_DIAG 406 tristate "INET: socket monitoring interface" 407 default y 408 ---help--- 409 Support for INET (TCP, DCCP, etc) socket monitoring interface used by 410 native Linux tools such as ss. ss is included in iproute2, currently 411 downloadable at: 412 413 http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2 414 415 If unsure, say Y. 416 417config INET_TCP_DIAG 418 depends on INET_DIAG 419 def_tristate INET_DIAG 420 421config INET_UDP_DIAG 422 tristate "UDP: socket monitoring interface" 423 depends on INET_DIAG && (IPV6 || IPV6=n) 424 default n 425 ---help--- 426 Support for UDP socket monitoring interface used by the ss tool. 427 If unsure, say Y. 428 429menuconfig TCP_CONG_ADVANCED 430 bool "TCP: advanced congestion control" 431 ---help--- 432 Support for selection of various TCP congestion control 433 modules. 434 435 Nearly all users can safely say no here, and a safe default 436 selection will be made (CUBIC with new Reno as a fallback). 437 438 If unsure, say N. 439 440if TCP_CONG_ADVANCED 441 442config TCP_CONG_BIC 443 tristate "Binary Increase Congestion (BIC) control" 444 default m 445 ---help--- 446 BIC-TCP is a sender-side only change that ensures a linear RTT 447 fairness under large windows while offering both scalability and 448 bounded TCP-friendliness. The protocol combines two schemes 449 called additive increase and binary search increase. When the 450 congestion window is large, additive increase with a large 451 increment ensures linear RTT fairness as well as good 452 scalability. Under small congestion windows, binary search 453 increase provides TCP friendliness. 454 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/ 455 456config TCP_CONG_CUBIC 457 tristate "CUBIC TCP" 458 default y 459 ---help--- 460 This is version 2.0 of BIC-TCP which uses a cubic growth function 461 among other techniques. 462 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf 463 464config TCP_CONG_WESTWOOD 465 tristate "TCP Westwood+" 466 default m 467 ---help--- 468 TCP Westwood+ is a sender-side only modification of the TCP Reno 469 protocol stack that optimizes the performance of TCP congestion 470 control. It is based on end-to-end bandwidth estimation to set 471 congestion window and slow start threshold after a congestion 472 episode. Using this estimation, TCP Westwood+ adaptively sets a 473 slow start threshold and a congestion window which takes into 474 account the bandwidth used at the time congestion is experienced. 475 TCP Westwood+ significantly increases fairness wrt TCP Reno in 476 wired networks and throughput over wireless links. 477 478config TCP_CONG_HTCP 479 tristate "H-TCP" 480 default m 481 ---help--- 482 H-TCP is a send-side only modifications of the TCP Reno 483 protocol stack that optimizes the performance of TCP 484 congestion control for high speed network links. It uses a 485 modeswitch to change the alpha and beta parameters of TCP Reno 486 based on network conditions and in a way so as to be fair with 487 other Reno and H-TCP flows. 488 489config TCP_CONG_HSTCP 490 tristate "High Speed TCP" 491 default n 492 ---help--- 493 Sally Floyd's High Speed TCP (RFC 3649) congestion control. 494 A modification to TCP's congestion control mechanism for use 495 with large congestion windows. A table indicates how much to 496 increase the congestion window by when an ACK is received. 497 For more detail see http://www.icir.org/floyd/hstcp.html 498 499config TCP_CONG_HYBLA 500 tristate "TCP-Hybla congestion control algorithm" 501 default n 502 ---help--- 503 TCP-Hybla is a sender-side only change that eliminates penalization of 504 long-RTT, large-bandwidth connections, like when satellite legs are 505 involved, especially when sharing a common bottleneck with normal 506 terrestrial connections. 507 508config TCP_CONG_VEGAS 509 tristate "TCP Vegas" 510 default n 511 ---help--- 512 TCP Vegas is a sender-side only change to TCP that anticipates 513 the onset of congestion by estimating the bandwidth. TCP Vegas 514 adjusts the sending rate by modifying the congestion 515 window. TCP Vegas should provide less packet loss, but it is 516 not as aggressive as TCP Reno. 517 518config TCP_CONG_SCALABLE 519 tristate "Scalable TCP" 520 default n 521 ---help--- 522 Scalable TCP is a sender-side only change to TCP which uses a 523 MIMD congestion control algorithm which has some nice scaling 524 properties, though is known to have fairness issues. 525 See http://www.deneholme.net/tom/scalable/ 526 527config TCP_CONG_LP 528 tristate "TCP Low Priority" 529 default n 530 ---help--- 531 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is 532 to utilize only the excess network bandwidth as compared to the 533 ``fair share`` of bandwidth as targeted by TCP. 534 See http://www-ece.rice.edu/networks/TCP-LP/ 535 536config TCP_CONG_VENO 537 tristate "TCP Veno" 538 default n 539 ---help--- 540 TCP Veno is a sender-side only enhancement of TCP to obtain better 541 throughput over wireless networks. TCP Veno makes use of state 542 distinguishing to circumvent the difficult judgment of the packet loss 543 type. TCP Veno cuts down less congestion window in response to random 544 loss packets. 545 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186> 546 547config TCP_CONG_YEAH 548 tristate "YeAH TCP" 549 select TCP_CONG_VEGAS 550 default n 551 ---help--- 552 YeAH-TCP is a sender-side high-speed enabled TCP congestion control 553 algorithm, which uses a mixed loss/delay approach to compute the 554 congestion window. It's design goals target high efficiency, 555 internal, RTT and Reno fairness, resilience to link loss while 556 keeping network elements load as low as possible. 557 558 For further details look here: 559 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf 560 561config TCP_CONG_ILLINOIS 562 tristate "TCP Illinois" 563 default n 564 ---help--- 565 TCP-Illinois is a sender-side modification of TCP Reno for 566 high speed long delay links. It uses round-trip-time to 567 adjust the alpha and beta parameters to achieve a higher average 568 throughput and maintain fairness. 569 570 For further details see: 571 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html 572 573choice 574 prompt "Default TCP congestion control" 575 default DEFAULT_CUBIC 576 help 577 Select the TCP congestion control that will be used by default 578 for all connections. 579 580 config DEFAULT_BIC 581 bool "Bic" if TCP_CONG_BIC=y 582 583 config DEFAULT_CUBIC 584 bool "Cubic" if TCP_CONG_CUBIC=y 585 586 config DEFAULT_HTCP 587 bool "Htcp" if TCP_CONG_HTCP=y 588 589 config DEFAULT_HYBLA 590 bool "Hybla" if TCP_CONG_HYBLA=y 591 592 config DEFAULT_VEGAS 593 bool "Vegas" if TCP_CONG_VEGAS=y 594 595 config DEFAULT_VENO 596 bool "Veno" if TCP_CONG_VENO=y 597 598 config DEFAULT_WESTWOOD 599 bool "Westwood" if TCP_CONG_WESTWOOD=y 600 601 config DEFAULT_RENO 602 bool "Reno" 603 604endchoice 605 606endif 607 608config TCP_CONG_CUBIC 609 tristate 610 depends on !TCP_CONG_ADVANCED 611 default y 612 613config DEFAULT_TCP_CONG 614 string 615 default "bic" if DEFAULT_BIC 616 default "cubic" if DEFAULT_CUBIC 617 default "htcp" if DEFAULT_HTCP 618 default "hybla" if DEFAULT_HYBLA 619 default "vegas" if DEFAULT_VEGAS 620 default "westwood" if DEFAULT_WESTWOOD 621 default "veno" if DEFAULT_VENO 622 default "reno" if DEFAULT_RENO 623 default "cubic" 624 625config TCP_MD5SIG 626 bool "TCP: MD5 Signature Option support (RFC2385)" 627 select CRYPTO 628 select CRYPTO_MD5 629 ---help--- 630 RFC2385 specifies a method of giving MD5 protection to TCP sessions. 631 Its main (only?) use is to protect BGP sessions between core routers 632 on the Internet. 633 634 If unsure, say N. 635