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.
58 config IP_FIB_TRIE_STATS
59 bool "FIB TRIE statistics"
60 depends on IP_ADVANCED_ROUTER
62 Keep track of statistics on structure of FIB TRIE table.
63 Useful for testing and measuring TRIE performance.
65 config IP_MULTIPLE_TABLES
66 bool "IP: policy routing"
67 depends on IP_ADVANCED_ROUTER
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.
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/>.
84 config IP_ROUTE_MULTIPATH
85 bool "IP: equal cost multipath"
86 depends on IP_ADVANCED_ROUTER
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.
96 config IP_ROUTE_VERBOSE
97 bool "IP: verbose route monitoring"
98 depends on IP_ADVANCED_ROUTER
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
107 config IP_ROUTE_CLASSID
111 bool "IP: kernel level autoconfiguration"
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.
122 bool "IP: DHCP support"
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.
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.
139 bool "IP: BOOTP support"
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.
154 bool "IP: RARP support"
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.
167 tristate "IP: tunneling"
171 Tunneling means encapsulating data of one protocol type within
172 another protocol and sending it over a channel that understands the
173 encapsulating protocol. This particular tunneling driver implements
174 encapsulation of IP within IP, which sounds kind of pointless, but
175 can be useful if you want to make your (or some other) machine
176 appear on a different network than it physically is, or to use
177 mobile-IP facilities (allowing laptops to seamlessly move between
178 networks without changing their IP addresses).
180 Saying Y to this option will produce two modules ( = code which can
181 be inserted in and removed from the running kernel whenever you
182 want). Most people won't need this and can say N.
184 config NET_IPGRE_DEMUX
185 tristate "IP: GRE demultiplexer"
187 This is helper module to demultiplex GRE packets on GRE version field criteria.
188 Required by ip_gre and pptp modules.
195 tristate "IP: GRE tunnels over IP"
196 depends on (IPV6 || IPV6=n) && NET_IPGRE_DEMUX
199 Tunneling means encapsulating data of one protocol type within
200 another protocol and sending it over a channel that understands the
201 encapsulating protocol. This particular tunneling driver implements
202 GRE (Generic Routing Encapsulation) and at this time allows
203 encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure.
204 This driver is useful if the other endpoint is a Cisco router: Cisco
205 likes GRE much better than the other Linux tunneling driver ("IP
206 tunneling" above). In addition, GRE allows multicast redistribution
209 config NET_IPGRE_BROADCAST
210 bool "IP: broadcast GRE over IP"
211 depends on IP_MULTICAST && NET_IPGRE
213 One application of GRE/IP is to construct a broadcast WAN (Wide Area
214 Network), which looks like a normal Ethernet LAN (Local Area
215 Network), but can be distributed all over the Internet. If you want
216 to do that, say Y here and to "IP multicast routing" below.
219 bool "IP: multicast routing"
220 depends on IP_MULTICAST
222 This is used if you want your machine to act as a router for IP
223 packets that have several destination addresses. It is needed on the
224 MBONE, a high bandwidth network on top of the Internet which carries
225 audio and video broadcasts. In order to do that, you would most
226 likely run the program mrouted. Information about the multicast
227 capabilities of the various network cards is contained in
228 <file:Documentation/networking/multicast.txt>. If you haven't heard
229 about it, you don't need it.
231 config IP_MROUTE_MULTIPLE_TABLES
232 bool "IP: multicast policy routing"
233 depends on IP_MROUTE && IP_ADVANCED_ROUTER
236 Normally, a multicast router runs a userspace daemon and decides
237 what to do with a multicast packet based on the source and
238 destination addresses. If you say Y here, the multicast router
239 will also be able to take interfaces and packet marks into
240 account and run multiple instances of userspace daemons
241 simultaneously, each one handling a single table.
246 bool "IP: PIM-SM version 1 support"
249 Kernel side support for Sparse Mode PIM (Protocol Independent
250 Multicast) version 1. This multicast routing protocol is used widely
251 because Cisco supports it. You need special software to use it
252 (pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
253 information about PIM.
255 Say Y if you want to use PIM-SM v1. Note that you can say N here if
256 you just want to use Dense Mode PIM.
259 bool "IP: PIM-SM version 2 support"
262 Kernel side support for Sparse Mode PIM version 2. In order to use
263 this, you need an experimental routing daemon supporting it (pimd or
264 gated-5). This routing protocol is not used widely, so say N unless
265 you want to play with it.
268 bool "IP: ARP daemon support"
270 The kernel maintains an internal cache which maps IP addresses to
271 hardware addresses on the local network, so that Ethernet
272 frames are sent to the proper address on the physical networking
273 layer. Normally, kernel uses the ARP protocol to resolve these
276 Saying Y here adds support to have an user space daemon to do this
277 resolution instead. This is useful for implementing an alternate
278 address resolution protocol (e.g. NHRP on mGRE tunnels) and also for
284 bool "IP: TCP syncookie support"
286 Normal TCP/IP networking is open to an attack known as "SYN
287 flooding". This denial-of-service attack prevents legitimate remote
288 users from being able to connect to your computer during an ongoing
289 attack and requires very little work from the attacker, who can
290 operate from anywhere on the Internet.
292 SYN cookies provide protection against this type of attack. If you
293 say Y here, the TCP/IP stack will use a cryptographic challenge
294 protocol known as "SYN cookies" to enable legitimate users to
295 continue to connect, even when your machine is under attack. There
296 is no need for the legitimate users to change their TCP/IP software;
297 SYN cookies work transparently to them. For technical information
298 about SYN cookies, check out <http://cr.yp.to/syncookies.html>.
300 If you are SYN flooded, the source address reported by the kernel is
301 likely to have been forged by the attacker; it is only reported as
302 an aid in tracing the packets to their actual source and should not
303 be taken as absolute truth.
305 SYN cookies may prevent correct error reporting on clients when the
306 server is really overloaded. If this happens frequently better turn
309 If you say Y here, you can disable SYN cookies at run time by
310 saying Y to "/proc file system support" and
311 "Sysctl support" below and executing the command
313 echo 0 > /proc/sys/net/ipv4/tcp_syncookies
315 after the /proc file system has been mounted.
320 tristate "Virtual (secure) IP: tunneling"
323 depends on INET_XFRM_MODE_TUNNEL
325 Tunneling means encapsulating data of one protocol type within
326 another protocol and sending it over a channel that understands the
327 encapsulating protocol. This can be used with xfrm mode tunnel to give
328 the notion of a secure tunnel for IPSEC and then use routing protocol
332 tristate "IP: AH transformation"
339 Support for IPsec AH.
344 tristate "IP: ESP transformation"
347 select CRYPTO_AUTHENC
354 Support for IPsec ESP.
359 tristate "IP: IPComp transformation"
360 select INET_XFRM_TUNNEL
363 Support for IP Payload Compression Protocol (IPComp) (RFC3173),
364 typically needed for IPsec.
368 config INET_XFRM_TUNNEL
377 config INET_XFRM_MODE_TRANSPORT
378 tristate "IP: IPsec transport mode"
382 Support for IPsec transport mode.
386 config INET_XFRM_MODE_TUNNEL
387 tristate "IP: IPsec tunnel mode"
391 Support for IPsec tunnel mode.
395 config INET_XFRM_MODE_BEET
396 tristate "IP: IPsec BEET mode"
400 Support for IPsec BEET mode.
405 tristate "Large Receive Offload (ipv4/tcp)"
408 Support for Large Receive Offload (ipv4/tcp).
413 tristate "INET: socket monitoring interface"
416 Support for INET (TCP, DCCP, etc) socket monitoring interface used by
417 native Linux tools such as ss. ss is included in iproute2, currently
420 http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2
426 def_tristate INET_DIAG
429 tristate "UDP: socket monitoring interface"
430 depends on INET_DIAG && (IPV6 || IPV6=n)
433 Support for UDP socket monitoring interface used by the ss tool.
436 menuconfig TCP_CONG_ADVANCED
437 bool "TCP: advanced congestion control"
439 Support for selection of various TCP congestion control
442 Nearly all users can safely say no here, and a safe default
443 selection will be made (CUBIC with new Reno as a fallback).
450 tristate "Binary Increase Congestion (BIC) control"
453 BIC-TCP is a sender-side only change that ensures a linear RTT
454 fairness under large windows while offering both scalability and
455 bounded TCP-friendliness. The protocol combines two schemes
456 called additive increase and binary search increase. When the
457 congestion window is large, additive increase with a large
458 increment ensures linear RTT fairness as well as good
459 scalability. Under small congestion windows, binary search
460 increase provides TCP friendliness.
461 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
463 config TCP_CONG_CUBIC
467 This is version 2.0 of BIC-TCP which uses a cubic growth function
468 among other techniques.
469 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
471 config TCP_CONG_WESTWOOD
472 tristate "TCP Westwood+"
475 TCP Westwood+ is a sender-side only modification of the TCP Reno
476 protocol stack that optimizes the performance of TCP congestion
477 control. It is based on end-to-end bandwidth estimation to set
478 congestion window and slow start threshold after a congestion
479 episode. Using this estimation, TCP Westwood+ adaptively sets a
480 slow start threshold and a congestion window which takes into
481 account the bandwidth used at the time congestion is experienced.
482 TCP Westwood+ significantly increases fairness wrt TCP Reno in
483 wired networks and throughput over wireless links.
489 H-TCP is a send-side only modifications of the TCP Reno
490 protocol stack that optimizes the performance of TCP
491 congestion control for high speed network links. It uses a
492 modeswitch to change the alpha and beta parameters of TCP Reno
493 based on network conditions and in a way so as to be fair with
494 other Reno and H-TCP flows.
496 config TCP_CONG_HSTCP
497 tristate "High Speed TCP"
500 Sally Floyd's High Speed TCP (RFC 3649) congestion control.
501 A modification to TCP's congestion control mechanism for use
502 with large congestion windows. A table indicates how much to
503 increase the congestion window by when an ACK is received.
504 For more detail see http://www.icir.org/floyd/hstcp.html
506 config TCP_CONG_HYBLA
507 tristate "TCP-Hybla congestion control algorithm"
510 TCP-Hybla is a sender-side only change that eliminates penalization of
511 long-RTT, large-bandwidth connections, like when satellite legs are
512 involved, especially when sharing a common bottleneck with normal
513 terrestrial connections.
515 config TCP_CONG_VEGAS
519 TCP Vegas is a sender-side only change to TCP that anticipates
520 the onset of congestion by estimating the bandwidth. TCP Vegas
521 adjusts the sending rate by modifying the congestion
522 window. TCP Vegas should provide less packet loss, but it is
523 not as aggressive as TCP Reno.
525 config TCP_CONG_SCALABLE
526 tristate "Scalable TCP"
529 Scalable TCP is a sender-side only change to TCP which uses a
530 MIMD congestion control algorithm which has some nice scaling
531 properties, though is known to have fairness issues.
532 See http://www.deneholme.net/tom/scalable/
535 tristate "TCP Low Priority"
538 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
539 to utilize only the excess network bandwidth as compared to the
540 ``fair share`` of bandwidth as targeted by TCP.
541 See http://www-ece.rice.edu/networks/TCP-LP/
547 TCP Veno is a sender-side only enhancement of TCP to obtain better
548 throughput over wireless networks. TCP Veno makes use of state
549 distinguishing to circumvent the difficult judgment of the packet loss
550 type. TCP Veno cuts down less congestion window in response to random
552 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
556 select TCP_CONG_VEGAS
559 YeAH-TCP is a sender-side high-speed enabled TCP congestion control
560 algorithm, which uses a mixed loss/delay approach to compute the
561 congestion window. It's design goals target high efficiency,
562 internal, RTT and Reno fairness, resilience to link loss while
563 keeping network elements load as low as possible.
565 For further details look here:
566 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
568 config TCP_CONG_ILLINOIS
569 tristate "TCP Illinois"
572 TCP-Illinois is a sender-side modification of TCP Reno for
573 high speed long delay links. It uses round-trip-time to
574 adjust the alpha and beta parameters to achieve a higher average
575 throughput and maintain fairness.
577 For further details see:
578 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
581 prompt "Default TCP congestion control"
582 default DEFAULT_CUBIC
584 Select the TCP congestion control that will be used by default
588 bool "Bic" if TCP_CONG_BIC=y
591 bool "Cubic" if TCP_CONG_CUBIC=y
594 bool "Htcp" if TCP_CONG_HTCP=y
597 bool "Hybla" if TCP_CONG_HYBLA=y
600 bool "Vegas" if TCP_CONG_VEGAS=y
603 bool "Veno" if TCP_CONG_VENO=y
605 config DEFAULT_WESTWOOD
606 bool "Westwood" if TCP_CONG_WESTWOOD=y
615 config TCP_CONG_CUBIC
617 depends on !TCP_CONG_ADVANCED
620 config DEFAULT_TCP_CONG
622 default "bic" if DEFAULT_BIC
623 default "cubic" if DEFAULT_CUBIC
624 default "htcp" if DEFAULT_HTCP
625 default "hybla" if DEFAULT_HYBLA
626 default "vegas" if DEFAULT_VEGAS
627 default "westwood" if DEFAULT_WESTWOOD
628 default "veno" if DEFAULT_VENO
629 default "reno" if DEFAULT_RENO
633 bool "TCP: MD5 Signature Option support (RFC2385)"
637 RFC2385 specifies a method of giving MD5 protection to TCP sessions.
638 Its main (only?) use is to protect BGP sessions between core routers