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/>. For most people, it's safe to say N. 13 14config 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 55config 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 62config 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 81config 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 93config 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 104config IP_ROUTE_CLASSID 105 bool 106 107config 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 118config 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 135config 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 150config 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 163config 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 181config 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 187config NET_IP_TUNNEL 188 tristate 189 default n 190 191config 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 206config 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 215config 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 226config 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 240config 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 253config 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 262config ARPD 263 bool "IP: ARP daemon support" 264 ---help--- 265 The kernel maintains an internal cache which maps IP addresses to 266 hardware addresses on the local network, so that Ethernet 267 frames are sent to the proper address on the physical networking 268 layer. Normally, kernel uses the ARP protocol to resolve these 269 mappings. 270 271 Saying Y here adds support to have an user space daemon to do this 272 resolution instead. This is useful for implementing an alternate 273 address resolution protocol (e.g. NHRP on mGRE tunnels) and also for 274 testing purposes. 275 276 If unsure, say N. 277 278config SYN_COOKIES 279 bool "IP: TCP syncookie support" 280 ---help--- 281 Normal TCP/IP networking is open to an attack known as "SYN 282 flooding". This denial-of-service attack prevents legitimate remote 283 users from being able to connect to your computer during an ongoing 284 attack and requires very little work from the attacker, who can 285 operate from anywhere on the Internet. 286 287 SYN cookies provide protection against this type of attack. If you 288 say Y here, the TCP/IP stack will use a cryptographic challenge 289 protocol known as "SYN cookies" to enable legitimate users to 290 continue to connect, even when your machine is under attack. There 291 is no need for the legitimate users to change their TCP/IP software; 292 SYN cookies work transparently to them. For technical information 293 about SYN cookies, check out <http://cr.yp.to/syncookies.html>. 294 295 If you are SYN flooded, the source address reported by the kernel is 296 likely to have been forged by the attacker; it is only reported as 297 an aid in tracing the packets to their actual source and should not 298 be taken as absolute truth. 299 300 SYN cookies may prevent correct error reporting on clients when the 301 server is really overloaded. If this happens frequently better turn 302 them off. 303 304 If you say Y here, you can disable SYN cookies at run time by 305 saying Y to "/proc file system support" and 306 "Sysctl support" below and executing the command 307 308 echo 0 > /proc/sys/net/ipv4/tcp_syncookies 309 310 after the /proc file system has been mounted. 311 312 If unsure, say N. 313 314config NET_IPVTI 315 tristate "Virtual (secure) IP: tunneling" 316 select INET_TUNNEL 317 select NET_IP_TUNNEL 318 depends on INET_XFRM_MODE_TUNNEL 319 ---help--- 320 Tunneling means encapsulating data of one protocol type within 321 another protocol and sending it over a channel that understands the 322 encapsulating protocol. This can be used with xfrm mode tunnel to give 323 the notion of a secure tunnel for IPSEC and then use routing protocol 324 on top. 325 326config INET_AH 327 tristate "IP: AH transformation" 328 select XFRM_ALGO 329 select CRYPTO 330 select CRYPTO_HMAC 331 select CRYPTO_MD5 332 select CRYPTO_SHA1 333 ---help--- 334 Support for IPsec AH. 335 336 If unsure, say Y. 337 338config INET_ESP 339 tristate "IP: ESP transformation" 340 select XFRM_ALGO 341 select CRYPTO 342 select CRYPTO_AUTHENC 343 select CRYPTO_HMAC 344 select CRYPTO_MD5 345 select CRYPTO_CBC 346 select CRYPTO_SHA1 347 select CRYPTO_DES 348 ---help--- 349 Support for IPsec ESP. 350 351 If unsure, say Y. 352 353config INET_IPCOMP 354 tristate "IP: IPComp transformation" 355 select INET_XFRM_TUNNEL 356 select XFRM_IPCOMP 357 ---help--- 358 Support for IP Payload Compression Protocol (IPComp) (RFC3173), 359 typically needed for IPsec. 360 361 If unsure, say Y. 362 363config INET_XFRM_TUNNEL 364 tristate 365 select INET_TUNNEL 366 default n 367 368config INET_TUNNEL 369 tristate 370 default n 371 372config INET_XFRM_MODE_TRANSPORT 373 tristate "IP: IPsec transport mode" 374 default y 375 select XFRM 376 ---help--- 377 Support for IPsec transport mode. 378 379 If unsure, say Y. 380 381config INET_XFRM_MODE_TUNNEL 382 tristate "IP: IPsec tunnel mode" 383 default y 384 select XFRM 385 ---help--- 386 Support for IPsec tunnel mode. 387 388 If unsure, say Y. 389 390config INET_XFRM_MODE_BEET 391 tristate "IP: IPsec BEET mode" 392 default y 393 select XFRM 394 ---help--- 395 Support for IPsec BEET mode. 396 397 If unsure, say Y. 398 399config INET_LRO 400 tristate "Large Receive Offload (ipv4/tcp)" 401 default y 402 ---help--- 403 Support for Large Receive Offload (ipv4/tcp). 404 405 If unsure, say Y. 406 407config INET_DIAG 408 tristate "INET: socket monitoring interface" 409 default y 410 ---help--- 411 Support for INET (TCP, DCCP, etc) socket monitoring interface used by 412 native Linux tools such as ss. ss is included in iproute2, currently 413 downloadable at: 414 415 http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2 416 417 If unsure, say Y. 418 419config INET_TCP_DIAG 420 depends on INET_DIAG 421 def_tristate INET_DIAG 422 423config INET_UDP_DIAG 424 tristate "UDP: socket monitoring interface" 425 depends on INET_DIAG && (IPV6 || IPV6=n) 426 default n 427 ---help--- 428 Support for UDP socket monitoring interface used by the ss tool. 429 If unsure, say Y. 430 431menuconfig TCP_CONG_ADVANCED 432 bool "TCP: advanced congestion control" 433 ---help--- 434 Support for selection of various TCP congestion control 435 modules. 436 437 Nearly all users can safely say no here, and a safe default 438 selection will be made (CUBIC with new Reno as a fallback). 439 440 If unsure, say N. 441 442if TCP_CONG_ADVANCED 443 444config TCP_CONG_BIC 445 tristate "Binary Increase Congestion (BIC) control" 446 default m 447 ---help--- 448 BIC-TCP is a sender-side only change that ensures a linear RTT 449 fairness under large windows while offering both scalability and 450 bounded TCP-friendliness. The protocol combines two schemes 451 called additive increase and binary search increase. When the 452 congestion window is large, additive increase with a large 453 increment ensures linear RTT fairness as well as good 454 scalability. Under small congestion windows, binary search 455 increase provides TCP friendliness. 456 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/ 457 458config TCP_CONG_CUBIC 459 tristate "CUBIC TCP" 460 default y 461 ---help--- 462 This is version 2.0 of BIC-TCP which uses a cubic growth function 463 among other techniques. 464 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf 465 466config TCP_CONG_WESTWOOD 467 tristate "TCP Westwood+" 468 default m 469 ---help--- 470 TCP Westwood+ is a sender-side only modification of the TCP Reno 471 protocol stack that optimizes the performance of TCP congestion 472 control. It is based on end-to-end bandwidth estimation to set 473 congestion window and slow start threshold after a congestion 474 episode. Using this estimation, TCP Westwood+ adaptively sets a 475 slow start threshold and a congestion window which takes into 476 account the bandwidth used at the time congestion is experienced. 477 TCP Westwood+ significantly increases fairness wrt TCP Reno in 478 wired networks and throughput over wireless links. 479 480config TCP_CONG_HTCP 481 tristate "H-TCP" 482 default m 483 ---help--- 484 H-TCP is a send-side only modifications of the TCP Reno 485 protocol stack that optimizes the performance of TCP 486 congestion control for high speed network links. It uses a 487 modeswitch to change the alpha and beta parameters of TCP Reno 488 based on network conditions and in a way so as to be fair with 489 other Reno and H-TCP flows. 490 491config TCP_CONG_HSTCP 492 tristate "High Speed TCP" 493 default n 494 ---help--- 495 Sally Floyd's High Speed TCP (RFC 3649) congestion control. 496 A modification to TCP's congestion control mechanism for use 497 with large congestion windows. A table indicates how much to 498 increase the congestion window by when an ACK is received. 499 For more detail see http://www.icir.org/floyd/hstcp.html 500 501config TCP_CONG_HYBLA 502 tristate "TCP-Hybla congestion control algorithm" 503 default n 504 ---help--- 505 TCP-Hybla is a sender-side only change that eliminates penalization of 506 long-RTT, large-bandwidth connections, like when satellite legs are 507 involved, especially when sharing a common bottleneck with normal 508 terrestrial connections. 509 510config TCP_CONG_VEGAS 511 tristate "TCP Vegas" 512 default n 513 ---help--- 514 TCP Vegas is a sender-side only change to TCP that anticipates 515 the onset of congestion by estimating the bandwidth. TCP Vegas 516 adjusts the sending rate by modifying the congestion 517 window. TCP Vegas should provide less packet loss, but it is 518 not as aggressive as TCP Reno. 519 520config TCP_CONG_SCALABLE 521 tristate "Scalable TCP" 522 default n 523 ---help--- 524 Scalable TCP is a sender-side only change to TCP which uses a 525 MIMD congestion control algorithm which has some nice scaling 526 properties, though is known to have fairness issues. 527 See http://www.deneholme.net/tom/scalable/ 528 529config TCP_CONG_LP 530 tristate "TCP Low Priority" 531 default n 532 ---help--- 533 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is 534 to utilize only the excess network bandwidth as compared to the 535 ``fair share`` of bandwidth as targeted by TCP. 536 See http://www-ece.rice.edu/networks/TCP-LP/ 537 538config TCP_CONG_VENO 539 tristate "TCP Veno" 540 default n 541 ---help--- 542 TCP Veno is a sender-side only enhancement of TCP to obtain better 543 throughput over wireless networks. TCP Veno makes use of state 544 distinguishing to circumvent the difficult judgment of the packet loss 545 type. TCP Veno cuts down less congestion window in response to random 546 loss packets. 547 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186> 548 549config TCP_CONG_YEAH 550 tristate "YeAH TCP" 551 select TCP_CONG_VEGAS 552 default n 553 ---help--- 554 YeAH-TCP is a sender-side high-speed enabled TCP congestion control 555 algorithm, which uses a mixed loss/delay approach to compute the 556 congestion window. It's design goals target high efficiency, 557 internal, RTT and Reno fairness, resilience to link loss while 558 keeping network elements load as low as possible. 559 560 For further details look here: 561 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf 562 563config TCP_CONG_ILLINOIS 564 tristate "TCP Illinois" 565 default n 566 ---help--- 567 TCP-Illinois is a sender-side modification of TCP Reno for 568 high speed long delay links. It uses round-trip-time to 569 adjust the alpha and beta parameters to achieve a higher average 570 throughput and maintain fairness. 571 572 For further details see: 573 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html 574 575choice 576 prompt "Default TCP congestion control" 577 default DEFAULT_CUBIC 578 help 579 Select the TCP congestion control that will be used by default 580 for all connections. 581 582 config DEFAULT_BIC 583 bool "Bic" if TCP_CONG_BIC=y 584 585 config DEFAULT_CUBIC 586 bool "Cubic" if TCP_CONG_CUBIC=y 587 588 config DEFAULT_HTCP 589 bool "Htcp" if TCP_CONG_HTCP=y 590 591 config DEFAULT_HYBLA 592 bool "Hybla" if TCP_CONG_HYBLA=y 593 594 config DEFAULT_VEGAS 595 bool "Vegas" if TCP_CONG_VEGAS=y 596 597 config DEFAULT_VENO 598 bool "Veno" if TCP_CONG_VENO=y 599 600 config DEFAULT_WESTWOOD 601 bool "Westwood" if TCP_CONG_WESTWOOD=y 602 603 config DEFAULT_RENO 604 bool "Reno" 605 606endchoice 607 608endif 609 610config TCP_CONG_CUBIC 611 tristate 612 depends on !TCP_CONG_ADVANCED 613 default y 614 615config DEFAULT_TCP_CONG 616 string 617 default "bic" if DEFAULT_BIC 618 default "cubic" if DEFAULT_CUBIC 619 default "htcp" if DEFAULT_HTCP 620 default "hybla" if DEFAULT_HYBLA 621 default "vegas" if DEFAULT_VEGAS 622 default "westwood" if DEFAULT_WESTWOOD 623 default "veno" if DEFAULT_VENO 624 default "reno" if DEFAULT_RENO 625 default "cubic" 626 627config TCP_MD5SIG 628 bool "TCP: MD5 Signature Option support (RFC2385)" 629 select CRYPTO 630 select CRYPTO_MD5 631 ---help--- 632 RFC2385 specifies a method of giving MD5 protection to TCP sessions. 633 Its main (only?) use is to protect BGP sessions between core routers 634 on the Internet. 635 636 If unsure, say N. 637