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Linux/net/ipv4/Kconfig

  1 #
  2 # IP configuration
  3 #
  4 config 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 
 14 config 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 
 55 config 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 
 62 config 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 
 81 config 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 
 93 config 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 
104 config IP_ROUTE_CLASSID
105         bool
106 
107 config 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 
118 config 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 
135 config 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 
150 config 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 
163 config 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 
181 config 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 
187 config NET_IP_TUNNEL
188         tristate
189         default n
190 
191 config 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 
206 config 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 
215 config 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 
226 config 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 
240 config 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 
253 config 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 
262 config SYN_COOKIES
263         bool "IP: TCP syncookie support"
264         ---help---
265           Normal TCP/IP networking is open to an attack known as "SYN
266           flooding". This denial-of-service attack prevents legitimate remote
267           users from being able to connect to your computer during an ongoing
268           attack and requires very little work from the attacker, who can
269           operate from anywhere on the Internet.
270 
271           SYN cookies provide protection against this type of attack. If you
272           say Y here, the TCP/IP stack will use a cryptographic challenge
273           protocol known as "SYN cookies" to enable legitimate users to
274           continue to connect, even when your machine is under attack. There
275           is no need for the legitimate users to change their TCP/IP software;
276           SYN cookies work transparently to them. For technical information
277           about SYN cookies, check out <http://cr.yp.to/syncookies.html>.
278 
279           If you are SYN flooded, the source address reported by the kernel is
280           likely to have been forged by the attacker; it is only reported as
281           an aid in tracing the packets to their actual source and should not
282           be taken as absolute truth.
283 
284           SYN cookies may prevent correct error reporting on clients when the
285           server is really overloaded. If this happens frequently better turn
286           them off.
287 
288           If you say Y here, you can disable SYN cookies at run time by
289           saying Y to "/proc file system support" and
290           "Sysctl support" below and executing the command
291 
292           echo 0 > /proc/sys/net/ipv4/tcp_syncookies
293 
294           after the /proc file system has been mounted.
295 
296           If unsure, say N.
297 
298 config NET_IPVTI
299         tristate "Virtual (secure) IP: tunneling"
300         select INET_TUNNEL
301         select NET_IP_TUNNEL
302         depends on INET_XFRM_MODE_TUNNEL
303         ---help---
304           Tunneling means encapsulating data of one protocol type within
305           another protocol and sending it over a channel that understands the
306           encapsulating protocol. This can be used with xfrm mode tunnel to give
307           the notion of a secure tunnel for IPSEC and then use routing protocol
308           on top.
309 
310 config INET_AH
311         tristate "IP: AH transformation"
312         select XFRM_ALGO
313         select CRYPTO
314         select CRYPTO_HMAC
315         select CRYPTO_MD5
316         select CRYPTO_SHA1
317         ---help---
318           Support for IPsec AH.
319 
320           If unsure, say Y.
321 
322 config INET_ESP
323         tristate "IP: ESP transformation"
324         select XFRM_ALGO
325         select CRYPTO
326         select CRYPTO_AUTHENC
327         select CRYPTO_HMAC
328         select CRYPTO_MD5
329         select CRYPTO_CBC
330         select CRYPTO_SHA1
331         select CRYPTO_DES
332         ---help---
333           Support for IPsec ESP.
334 
335           If unsure, say Y.
336 
337 config INET_IPCOMP
338         tristate "IP: IPComp transformation"
339         select INET_XFRM_TUNNEL
340         select XFRM_IPCOMP
341         ---help---
342           Support for IP Payload Compression Protocol (IPComp) (RFC3173),
343           typically needed for IPsec.
344 
345           If unsure, say Y.
346 
347 config INET_XFRM_TUNNEL
348         tristate
349         select INET_TUNNEL
350         default n
351 
352 config INET_TUNNEL
353         tristate
354         default n
355 
356 config INET_XFRM_MODE_TRANSPORT
357         tristate "IP: IPsec transport mode"
358         default y
359         select XFRM
360         ---help---
361           Support for IPsec transport mode.
362 
363           If unsure, say Y.
364 
365 config INET_XFRM_MODE_TUNNEL
366         tristate "IP: IPsec tunnel mode"
367         default y
368         select XFRM
369         ---help---
370           Support for IPsec tunnel mode.
371 
372           If unsure, say Y.
373 
374 config INET_XFRM_MODE_BEET
375         tristate "IP: IPsec BEET mode"
376         default y
377         select XFRM
378         ---help---
379           Support for IPsec BEET mode.
380 
381           If unsure, say Y.
382 
383 config INET_LRO
384         tristate "Large Receive Offload (ipv4/tcp)"
385         default y
386         ---help---
387           Support for Large Receive Offload (ipv4/tcp).
388 
389           If unsure, say Y.
390 
391 config INET_DIAG
392         tristate "INET: socket monitoring interface"
393         default y
394         ---help---
395           Support for INET (TCP, DCCP, etc) socket monitoring interface used by
396           native Linux tools such as ss. ss is included in iproute2, currently
397           downloadable at:
398           
399             http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2
400 
401           If unsure, say Y.
402 
403 config INET_TCP_DIAG
404         depends on INET_DIAG
405         def_tristate INET_DIAG
406 
407 config INET_UDP_DIAG
408         tristate "UDP: socket monitoring interface"
409         depends on INET_DIAG && (IPV6 || IPV6=n)
410         default n
411         ---help---
412           Support for UDP socket monitoring interface used by the ss tool.
413           If unsure, say Y.
414 
415 menuconfig TCP_CONG_ADVANCED
416         bool "TCP: advanced congestion control"
417         ---help---
418           Support for selection of various TCP congestion control
419           modules.
420 
421           Nearly all users can safely say no here, and a safe default
422           selection will be made (CUBIC with new Reno as a fallback).
423 
424           If unsure, say N.
425 
426 if TCP_CONG_ADVANCED
427 
428 config TCP_CONG_BIC
429         tristate "Binary Increase Congestion (BIC) control"
430         default m
431         ---help---
432         BIC-TCP is a sender-side only change that ensures a linear RTT
433         fairness under large windows while offering both scalability and
434         bounded TCP-friendliness. The protocol combines two schemes
435         called additive increase and binary search increase. When the
436         congestion window is large, additive increase with a large
437         increment ensures linear RTT fairness as well as good
438         scalability. Under small congestion windows, binary search
439         increase provides TCP friendliness.
440         See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
441 
442 config TCP_CONG_CUBIC
443         tristate "CUBIC TCP"
444         default y
445         ---help---
446         This is version 2.0 of BIC-TCP which uses a cubic growth function
447         among other techniques.
448         See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
449 
450 config TCP_CONG_WESTWOOD
451         tristate "TCP Westwood+"
452         default m
453         ---help---
454         TCP Westwood+ is a sender-side only modification of the TCP Reno
455         protocol stack that optimizes the performance of TCP congestion
456         control. It is based on end-to-end bandwidth estimation to set
457         congestion window and slow start threshold after a congestion
458         episode. Using this estimation, TCP Westwood+ adaptively sets a
459         slow start threshold and a congestion window which takes into
460         account the bandwidth used  at the time congestion is experienced.
461         TCP Westwood+ significantly increases fairness wrt TCP Reno in
462         wired networks and throughput over wireless links.
463 
464 config TCP_CONG_HTCP
465         tristate "H-TCP"
466         default m
467         ---help---
468         H-TCP is a send-side only modifications of the TCP Reno
469         protocol stack that optimizes the performance of TCP
470         congestion control for high speed network links. It uses a
471         modeswitch to change the alpha and beta parameters of TCP Reno
472         based on network conditions and in a way so as to be fair with
473         other Reno and H-TCP flows.
474 
475 config TCP_CONG_HSTCP
476         tristate "High Speed TCP"
477         default n
478         ---help---
479         Sally Floyd's High Speed TCP (RFC 3649) congestion control.
480         A modification to TCP's congestion control mechanism for use
481         with large congestion windows. A table indicates how much to
482         increase the congestion window by when an ACK is received.
483         For more detail see http://www.icir.org/floyd/hstcp.html
484 
485 config TCP_CONG_HYBLA
486         tristate "TCP-Hybla congestion control algorithm"
487         default n
488         ---help---
489         TCP-Hybla is a sender-side only change that eliminates penalization of
490         long-RTT, large-bandwidth connections, like when satellite legs are
491         involved, especially when sharing a common bottleneck with normal
492         terrestrial connections.
493 
494 config TCP_CONG_VEGAS
495         tristate "TCP Vegas"
496         default n
497         ---help---
498         TCP Vegas is a sender-side only change to TCP that anticipates
499         the onset of congestion by estimating the bandwidth. TCP Vegas
500         adjusts the sending rate by modifying the congestion
501         window. TCP Vegas should provide less packet loss, but it is
502         not as aggressive as TCP Reno.
503 
504 config TCP_CONG_SCALABLE
505         tristate "Scalable TCP"
506         default n
507         ---help---
508         Scalable TCP is a sender-side only change to TCP which uses a
509         MIMD congestion control algorithm which has some nice scaling
510         properties, though is known to have fairness issues.
511         See http://www.deneholme.net/tom/scalable/
512 
513 config TCP_CONG_LP
514         tristate "TCP Low Priority"
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 
522 config TCP_CONG_VENO
523         tristate "TCP Veno"
524         default n
525         ---help---
526         TCP Veno is a sender-side only enhancement of TCP to obtain better
527         throughput over wireless networks. TCP Veno makes use of state
528         distinguishing to circumvent the difficult judgment of the packet loss
529         type. TCP Veno cuts down less congestion window in response to random
530         loss packets.
531         See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186> 
532 
533 config TCP_CONG_YEAH
534         tristate "YeAH TCP"
535         select TCP_CONG_VEGAS
536         default n
537         ---help---
538         YeAH-TCP is a sender-side high-speed enabled TCP congestion control
539         algorithm, which uses a mixed loss/delay approach to compute the
540         congestion window. It's design goals target high efficiency,
541         internal, RTT and Reno fairness, resilience to link loss while
542         keeping network elements load as low as possible.
543 
544         For further details look here:
545           http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
546 
547 config TCP_CONG_ILLINOIS
548         tristate "TCP Illinois"
549         default n
550         ---help---
551         TCP-Illinois is a sender-side modification of TCP Reno for
552         high speed long delay links. It uses round-trip-time to
553         adjust the alpha and beta parameters to achieve a higher average
554         throughput and maintain fairness.
555 
556         For further details see:
557           http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
558 
559 choice
560         prompt "Default TCP congestion control"
561         default DEFAULT_CUBIC
562         help
563           Select the TCP congestion control that will be used by default
564           for all connections.
565 
566         config DEFAULT_BIC
567                 bool "Bic" if TCP_CONG_BIC=y
568 
569         config DEFAULT_CUBIC
570                 bool "Cubic" if TCP_CONG_CUBIC=y
571 
572         config DEFAULT_HTCP
573                 bool "Htcp" if TCP_CONG_HTCP=y
574 
575         config DEFAULT_HYBLA
576                 bool "Hybla" if TCP_CONG_HYBLA=y
577 
578         config DEFAULT_VEGAS
579                 bool "Vegas" if TCP_CONG_VEGAS=y
580 
581         config DEFAULT_VENO
582                 bool "Veno" if TCP_CONG_VENO=y
583 
584         config DEFAULT_WESTWOOD
585                 bool "Westwood" if TCP_CONG_WESTWOOD=y
586 
587         config DEFAULT_RENO
588                 bool "Reno"
589 
590 endchoice
591 
592 endif
593 
594 config TCP_CONG_CUBIC
595         tristate
596         depends on !TCP_CONG_ADVANCED
597         default y
598 
599 config DEFAULT_TCP_CONG
600         string
601         default "bic" if DEFAULT_BIC
602         default "cubic" if DEFAULT_CUBIC
603         default "htcp" if DEFAULT_HTCP
604         default "hybla" if DEFAULT_HYBLA
605         default "vegas" if DEFAULT_VEGAS
606         default "westwood" if DEFAULT_WESTWOOD
607         default "veno" if DEFAULT_VENO
608         default "reno" if DEFAULT_RENO
609         default "cubic"
610 
611 config TCP_MD5SIG
612         bool "TCP: MD5 Signature Option support (RFC2385)"
613         select CRYPTO
614         select CRYPTO_MD5
615         ---help---
616           RFC2385 specifies a method of giving MD5 protection to TCP sessions.
617           Its main (only?) use is to protect BGP sessions between core routers
618           on the Internet.
619 
620           If unsure, say N.

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