5 bool "IP: multicasting"
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
17 config IP_ADVANCED_ROUTER
18 bool "IP: advanced router"
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.
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.
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
34 echo "1" > /proc/sys/net/ipv4/ip_forward
36 at boot time after the /proc file system has been mounted.
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
48 echo 1 > /proc/sys/net/ipv4/conf/<device>/rp_filter
50 echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
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>.
56 If unsure, say N here.
59 prompt "Choose IP: FIB lookup algorithm (choose FIB_HASH if unsure)"
60 depends on IP_ADVANCED_ROUTER
61 default ASK_IP_FIB_HASH
63 config ASK_IP_FIB_HASH
66 Current FIB is very proven and good enough for most users.
71 Use new experimental LC-trie as FIB lookup algorithm.
72 This improves lookup performance if you have a large
75 LC-trie is a longest matching prefix lookup algorithm which
76 performs better than FIB_HASH for large routing tables.
77 But, it consumes more memory and is more complex.
79 LC-trie is described in:
81 IP-address lookup using LC-tries. Stefan Nilsson and Gunnar Karlsson
82 IEEE Journal on Selected Areas in Communications, 17(6):1083-1092,
85 An experimental study of compression methods for dynamic tries
86 Stefan Nilsson and Matti Tikkanen. Algorithmica, 33(1):19-33, 2002.
87 <http://www.csc.kth.se/~snilsson/software/dyntrie2/>
92 def_bool ASK_IP_FIB_HASH || !IP_ADVANCED_ROUTER
94 config IP_FIB_TRIE_STATS
95 bool "FIB TRIE statistics"
96 depends on IP_FIB_TRIE
98 Keep track of statistics on structure of FIB TRIE table.
99 Useful for testing and measuring TRIE performance.
101 config IP_MULTIPLE_TABLES
102 bool "IP: policy routing"
103 depends on IP_ADVANCED_ROUTER
106 Normally, a router decides what to do with a received packet based
107 solely on the packet's final destination address. If you say Y here,
108 the Linux router will also be able to take the packet's source
109 address into account. Furthermore, the TOS (Type-Of-Service) field
110 of the packet can be used for routing decisions as well.
112 If you are interested in this, please see the preliminary
113 documentation at <http://www.compendium.com.ar/policy-routing.txt>
114 and <ftp://post.tepkom.ru/pub/vol2/Linux/docs/advanced-routing.tex>.
115 You will need supporting software from
116 <ftp://ftp.tux.org/pub/net/ip-routing/>.
120 config IP_ROUTE_MULTIPATH
121 bool "IP: equal cost multipath"
122 depends on IP_ADVANCED_ROUTER
124 Normally, the routing tables specify a single action to be taken in
125 a deterministic manner for a given packet. If you say Y here
126 however, it becomes possible to attach several actions to a packet
127 pattern, in effect specifying several alternative paths to travel
128 for those packets. The router considers all these paths to be of
129 equal "cost" and chooses one of them in a non-deterministic fashion
130 if a matching packet arrives.
132 config IP_ROUTE_VERBOSE
133 bool "IP: verbose route monitoring"
134 depends on IP_ADVANCED_ROUTER
136 If you say Y here, which is recommended, then the kernel will print
137 verbose messages regarding the routing, for example warnings about
138 received packets which look strange and could be evidence of an
139 attack or a misconfigured system somewhere. The information is
140 handled by the klogd daemon which is responsible for kernel messages
143 config IP_ROUTE_CLASSID
147 bool "IP: kernel level autoconfiguration"
149 This enables automatic configuration of IP addresses of devices and
150 of the routing table during kernel boot, based on either information
151 supplied on the kernel command line or by BOOTP or RARP protocols.
152 You need to say Y only for diskless machines requiring network
153 access to boot (in which case you want to say Y to "Root file system
154 on NFS" as well), because all other machines configure the network
155 in their startup scripts.
158 bool "IP: DHCP support"
161 If you want your Linux box to mount its whole root file system (the
162 one containing the directory /) from some other computer over the
163 net via NFS and you want the IP address of your computer to be
164 discovered automatically at boot time using the DHCP protocol (a
165 special protocol designed for doing this job), say Y here. In case
166 the boot ROM of your network card was designed for booting Linux and
167 does DHCP itself, providing all necessary information on the kernel
168 command line, you can say N here.
170 If unsure, say Y. Note that if you want to use DHCP, a DHCP server
171 must be operating on your network. Read
172 <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
175 bool "IP: BOOTP support"
178 If you want your Linux box to mount its whole root file system (the
179 one containing the directory /) from some other computer over the
180 net via NFS and you want the IP address of your computer to be
181 discovered automatically at boot time using the BOOTP protocol (a
182 special protocol designed for doing this job), say Y here. In case
183 the boot ROM of your network card was designed for booting Linux and
184 does BOOTP itself, providing all necessary information on the kernel
185 command line, you can say N here. If unsure, say Y. Note that if you
186 want to use BOOTP, a BOOTP server must be operating on your network.
187 Read <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
190 bool "IP: RARP support"
193 If you want your Linux box to mount its whole root file system (the
194 one containing the directory /) from some other computer over the
195 net via NFS and you want the IP address of your computer to be
196 discovered automatically at boot time using the RARP protocol (an
197 older protocol which is being obsoleted by BOOTP and DHCP), say Y
198 here. Note that if you want to use RARP, a RARP server must be
199 operating on your network. Read
200 <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
203 # bool ' IP: ARP support' CONFIG_IP_PNP_ARP
205 tristate "IP: tunneling"
208 Tunneling means encapsulating data of one protocol type within
209 another protocol and sending it over a channel that understands the
210 encapsulating protocol. This particular tunneling driver implements
211 encapsulation of IP within IP, which sounds kind of pointless, but
212 can be useful if you want to make your (or some other) machine
213 appear on a different network than it physically is, or to use
214 mobile-IP facilities (allowing laptops to seamlessly move between
215 networks without changing their IP addresses).
217 Saying Y to this option will produce two modules ( = code which can
218 be inserted in and removed from the running kernel whenever you
219 want). Most people won't need this and can say N.
221 config NET_IPGRE_DEMUX
222 tristate "IP: GRE demultiplexer"
224 This is helper module to demultiplex GRE packets on GRE version field criteria.
225 Required by ip_gre and pptp modules.
228 tristate "IP: GRE tunnels over IP"
229 depends on (IPV6 || IPV6=n) && NET_IPGRE_DEMUX
231 Tunneling means encapsulating data of one protocol type within
232 another protocol and sending it over a channel that understands the
233 encapsulating protocol. This particular tunneling driver implements
234 GRE (Generic Routing Encapsulation) and at this time allows
235 encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure.
236 This driver is useful if the other endpoint is a Cisco router: Cisco
237 likes GRE much better than the other Linux tunneling driver ("IP
238 tunneling" above). In addition, GRE allows multicast redistribution
241 config NET_IPGRE_BROADCAST
242 bool "IP: broadcast GRE over IP"
243 depends on IP_MULTICAST && NET_IPGRE
245 One application of GRE/IP is to construct a broadcast WAN (Wide Area
246 Network), which looks like a normal Ethernet LAN (Local Area
247 Network), but can be distributed all over the Internet. If you want
248 to do that, say Y here and to "IP multicast routing" below.
251 bool "IP: multicast routing"
252 depends on IP_MULTICAST
254 This is used if you want your machine to act as a router for IP
255 packets that have several destination addresses. It is needed on the
256 MBONE, a high bandwidth network on top of the Internet which carries
257 audio and video broadcasts. In order to do that, you would most
258 likely run the program mrouted. Information about the multicast
259 capabilities of the various network cards is contained in
260 <file:Documentation/networking/multicast.txt>. If you haven't heard
261 about it, you don't need it.
263 config IP_MROUTE_MULTIPLE_TABLES
264 bool "IP: multicast policy routing"
265 depends on IP_MROUTE && IP_ADVANCED_ROUTER
268 Normally, a multicast router runs a userspace daemon and decides
269 what to do with a multicast packet based on the source and
270 destination addresses. If you say Y here, the multicast router
271 will also be able to take interfaces and packet marks into
272 account and run multiple instances of userspace daemons
273 simultaneously, each one handling a single table.
278 bool "IP: PIM-SM version 1 support"
281 Kernel side support for Sparse Mode PIM (Protocol Independent
282 Multicast) version 1. This multicast routing protocol is used widely
283 because Cisco supports it. You need special software to use it
284 (pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
285 information about PIM.
287 Say Y if you want to use PIM-SM v1. Note that you can say N here if
288 you just want to use Dense Mode PIM.
291 bool "IP: PIM-SM version 2 support"
294 Kernel side support for Sparse Mode PIM version 2. In order to use
295 this, you need an experimental routing daemon supporting it (pimd or
296 gated-5). This routing protocol is not used widely, so say N unless
297 you want to play with it.
300 bool "IP: ARP daemon support"
302 The kernel maintains an internal cache which maps IP addresses to
303 hardware addresses on the local network, so that Ethernet/Token Ring/
304 etc. frames are sent to the proper address on the physical networking
305 layer. Normally, kernel uses the ARP protocol to resolve these
308 Saying Y here adds support to have an user space daemon to do this
309 resolution instead. This is useful for implementing an alternate
310 address resolution protocol (e.g. NHRP on mGRE tunnels) and also for
316 bool "IP: TCP syncookie support"
318 Normal TCP/IP networking is open to an attack known as "SYN
319 flooding". This denial-of-service attack prevents legitimate remote
320 users from being able to connect to your computer during an ongoing
321 attack and requires very little work from the attacker, who can
322 operate from anywhere on the Internet.
324 SYN cookies provide protection against this type of attack. If you
325 say Y here, the TCP/IP stack will use a cryptographic challenge
326 protocol known as "SYN cookies" to enable legitimate users to
327 continue to connect, even when your machine is under attack. There
328 is no need for the legitimate users to change their TCP/IP software;
329 SYN cookies work transparently to them. For technical information
330 about SYN cookies, check out <http://cr.yp.to/syncookies.html>.
332 If you are SYN flooded, the source address reported by the kernel is
333 likely to have been forged by the attacker; it is only reported as
334 an aid in tracing the packets to their actual source and should not
335 be taken as absolute truth.
337 SYN cookies may prevent correct error reporting on clients when the
338 server is really overloaded. If this happens frequently better turn
341 If you say Y here, you can disable SYN cookies at run time by
342 saying Y to "/proc file system support" and
343 "Sysctl support" below and executing the command
345 echo 0 > /proc/sys/net/ipv4/tcp_syncookies
347 after the /proc file system has been mounted.
352 tristate "IP: AH transformation"
359 Support for IPsec AH.
364 tristate "IP: ESP transformation"
367 select CRYPTO_AUTHENC
374 Support for IPsec ESP.
379 tristate "IP: IPComp transformation"
380 select INET_XFRM_TUNNEL
383 Support for IP Payload Compression Protocol (IPComp) (RFC3173),
384 typically needed for IPsec.
388 config INET_XFRM_TUNNEL
397 config INET_XFRM_MODE_TRANSPORT
398 tristate "IP: IPsec transport mode"
402 Support for IPsec transport mode.
406 config INET_XFRM_MODE_TUNNEL
407 tristate "IP: IPsec tunnel mode"
411 Support for IPsec tunnel mode.
415 config INET_XFRM_MODE_BEET
416 tristate "IP: IPsec BEET mode"
420 Support for IPsec BEET mode.
425 tristate "Large Receive Offload (ipv4/tcp)"
428 Support for Large Receive Offload (ipv4/tcp).
433 tristate "INET: socket monitoring interface"
436 Support for INET (TCP, DCCP, etc) socket monitoring interface used by
437 native Linux tools such as ss. ss is included in iproute2, currently
438 downloadable at <http://linux-net.osdl.org/index.php/Iproute2>.
444 def_tristate INET_DIAG
446 menuconfig TCP_CONG_ADVANCED
447 bool "TCP: advanced congestion control"
449 Support for selection of various TCP congestion control
452 Nearly all users can safely say no here, and a safe default
453 selection will be made (CUBIC with new Reno as a fallback).
460 tristate "Binary Increase Congestion (BIC) control"
463 BIC-TCP is a sender-side only change that ensures a linear RTT
464 fairness under large windows while offering both scalability and
465 bounded TCP-friendliness. The protocol combines two schemes
466 called additive increase and binary search increase. When the
467 congestion window is large, additive increase with a large
468 increment ensures linear RTT fairness as well as good
469 scalability. Under small congestion windows, binary search
470 increase provides TCP friendliness.
471 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
473 config TCP_CONG_CUBIC
477 This is version 2.0 of BIC-TCP which uses a cubic growth function
478 among other techniques.
479 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
481 config TCP_CONG_WESTWOOD
482 tristate "TCP Westwood+"
485 TCP Westwood+ is a sender-side only modification of the TCP Reno
486 protocol stack that optimizes the performance of TCP congestion
487 control. It is based on end-to-end bandwidth estimation to set
488 congestion window and slow start threshold after a congestion
489 episode. Using this estimation, TCP Westwood+ adaptively sets a
490 slow start threshold and a congestion window which takes into
491 account the bandwidth used at the time congestion is experienced.
492 TCP Westwood+ significantly increases fairness wrt TCP Reno in
493 wired networks and throughput over wireless links.
499 H-TCP is a send-side only modifications of the TCP Reno
500 protocol stack that optimizes the performance of TCP
501 congestion control for high speed network links. It uses a
502 modeswitch to change the alpha and beta parameters of TCP Reno
503 based on network conditions and in a way so as to be fair with
504 other Reno and H-TCP flows.
506 config TCP_CONG_HSTCP
507 tristate "High Speed TCP"
508 depends on EXPERIMENTAL
511 Sally Floyd's High Speed TCP (RFC 3649) congestion control.
512 A modification to TCP's congestion control mechanism for use
513 with large congestion windows. A table indicates how much to
514 increase the congestion window by when an ACK is received.
515 For more detail see http://www.icir.org/floyd/hstcp.html
517 config TCP_CONG_HYBLA
518 tristate "TCP-Hybla congestion control algorithm"
519 depends on EXPERIMENTAL
522 TCP-Hybla is a sender-side only change that eliminates penalization of
523 long-RTT, large-bandwidth connections, like when satellite legs are
524 involved, especially when sharing a common bottleneck with normal
525 terrestrial connections.
527 config TCP_CONG_VEGAS
529 depends on EXPERIMENTAL
532 TCP Vegas is a sender-side only change to TCP that anticipates
533 the onset of congestion by estimating the bandwidth. TCP Vegas
534 adjusts the sending rate by modifying the congestion
535 window. TCP Vegas should provide less packet loss, but it is
536 not as aggressive as TCP Reno.
538 config TCP_CONG_SCALABLE
539 tristate "Scalable TCP"
540 depends on EXPERIMENTAL
543 Scalable TCP is a sender-side only change to TCP which uses a
544 MIMD congestion control algorithm which has some nice scaling
545 properties, though is known to have fairness issues.
546 See http://www.deneholme.net/tom/scalable/
549 tristate "TCP Low Priority"
550 depends on EXPERIMENTAL
553 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
554 to utilize only the excess network bandwidth as compared to the
555 ``fair share`` of bandwidth as targeted by TCP.
556 See http://www-ece.rice.edu/networks/TCP-LP/
560 depends on EXPERIMENTAL
563 TCP Veno is a sender-side only enhancement of TCP to obtain better
564 throughput over wireless networks. TCP Veno makes use of state
565 distinguishing to circumvent the difficult judgment of the packet loss
566 type. TCP Veno cuts down less congestion window in response to random
568 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
572 depends on EXPERIMENTAL
573 select TCP_CONG_VEGAS
576 YeAH-TCP is a sender-side high-speed enabled TCP congestion control
577 algorithm, which uses a mixed loss/delay approach to compute the
578 congestion window. It's design goals target high efficiency,
579 internal, RTT and Reno fairness, resilience to link loss while
580 keeping network elements load as low as possible.
582 For further details look here:
583 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
585 config TCP_CONG_ILLINOIS
586 tristate "TCP Illinois"
587 depends on EXPERIMENTAL
590 TCP-Illinois is a sender-side modification of TCP Reno for
591 high speed long delay links. It uses round-trip-time to
592 adjust the alpha and beta parameters to achieve a higher average
593 throughput and maintain fairness.
595 For further details see:
596 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
599 prompt "Default TCP congestion control"
600 default DEFAULT_CUBIC
602 Select the TCP congestion control that will be used by default
606 bool "Bic" if TCP_CONG_BIC=y
609 bool "Cubic" if TCP_CONG_CUBIC=y
612 bool "Htcp" if TCP_CONG_HTCP=y
615 bool "Hybla" if TCP_CONG_HYBLA=y
618 bool "Vegas" if TCP_CONG_VEGAS=y
621 bool "Veno" if TCP_CONG_VENO=y
623 config DEFAULT_WESTWOOD
624 bool "Westwood" if TCP_CONG_WESTWOOD=y
633 config TCP_CONG_CUBIC
635 depends on !TCP_CONG_ADVANCED
638 config DEFAULT_TCP_CONG
640 default "bic" if DEFAULT_BIC
641 default "cubic" if DEFAULT_CUBIC
642 default "htcp" if DEFAULT_HTCP
643 default "hybla" if DEFAULT_HYBLA
644 default "vegas" if DEFAULT_VEGAS
645 default "westwood" if DEFAULT_WESTWOOD
646 default "veno" if DEFAULT_VENO
647 default "reno" if DEFAULT_RENO
651 bool "TCP: MD5 Signature Option support (RFC2385) (EXPERIMENTAL)"
652 depends on EXPERIMENTAL
656 RFC2385 specifies a method of giving MD5 protection to TCP sessions.
657 Its main (only?) use is to protect BGP sessions between core routers