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"
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).
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.
183 config NET_IPGRE_DEMUX
184 tristate "IP: GRE demultiplexer"
186 This is helper module to demultiplex GRE packets on GRE version field criteria.
187 Required by ip_gre and pptp modules.
194 tristate "IP: GRE tunnels over IP"
195 depends on (IPV6 || IPV6=n) && NET_IPGRE_DEMUX
198 Tunneling means encapsulating data of one protocol type within
199 another protocol and sending it over a channel that understands the
200 encapsulating protocol. This particular tunneling driver implements
201 GRE (Generic Routing Encapsulation) and at this time allows
202 encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure.
203 This driver is useful if the other endpoint is a Cisco router: Cisco
204 likes GRE much better than the other Linux tunneling driver ("IP
205 tunneling" above). In addition, GRE allows multicast redistribution
208 config NET_IPGRE_BROADCAST
209 bool "IP: broadcast GRE over IP"
210 depends on IP_MULTICAST && NET_IPGRE
212 One application of GRE/IP is to construct a broadcast WAN (Wide Area
213 Network), which looks like a normal Ethernet LAN (Local Area
214 Network), but can be distributed all over the Internet. If you want
215 to do that, say Y here and to "IP multicast routing" below.
218 bool "IP: multicast routing"
219 depends on IP_MULTICAST
221 This is used if you want your machine to act as a router for IP
222 packets that have several destination addresses. It is needed on the
223 MBONE, a high bandwidth network on top of the Internet which carries
224 audio and video broadcasts. In order to do that, you would most
225 likely run the program mrouted. Information about the multicast
226 capabilities of the various network cards is contained in
227 <file:Documentation/networking/multicast.txt>. If you haven't heard
228 about it, you don't need it.
230 config IP_MROUTE_MULTIPLE_TABLES
231 bool "IP: multicast policy routing"
232 depends on IP_MROUTE && IP_ADVANCED_ROUTER
235 Normally, a multicast router runs a userspace daemon and decides
236 what to do with a multicast packet based on the source and
237 destination addresses. If you say Y here, the multicast router
238 will also be able to take interfaces and packet marks into
239 account and run multiple instances of userspace daemons
240 simultaneously, each one handling a single table.
245 bool "IP: PIM-SM version 1 support"
248 Kernel side support for Sparse Mode PIM (Protocol Independent
249 Multicast) version 1. This multicast routing protocol is used widely
250 because Cisco supports it. You need special software to use it
251 (pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
252 information about PIM.
254 Say Y if you want to use PIM-SM v1. Note that you can say N here if
255 you just want to use Dense Mode PIM.
258 bool "IP: PIM-SM version 2 support"
261 Kernel side support for Sparse Mode PIM version 2. In order to use
262 this, you need an experimental routing daemon supporting it (pimd or
263 gated-5). This routing protocol is not used widely, so say N unless
264 you want to play with it.
267 bool "IP: ARP daemon support"
269 The kernel maintains an internal cache which maps IP addresses to
270 hardware addresses on the local network, so that Ethernet
271 frames are sent to the proper address on the physical networking
272 layer. Normally, kernel uses the ARP protocol to resolve these
275 Saying Y here adds support to have an user space daemon to do this
276 resolution instead. This is useful for implementing an alternate
277 address resolution protocol (e.g. NHRP on mGRE tunnels) and also for
283 bool "IP: TCP syncookie support"
285 Normal TCP/IP networking is open to an attack known as "SYN
286 flooding". This denial-of-service attack prevents legitimate remote
287 users from being able to connect to your computer during an ongoing
288 attack and requires very little work from the attacker, who can
289 operate from anywhere on the Internet.
291 SYN cookies provide protection against this type of attack. If you
292 say Y here, the TCP/IP stack will use a cryptographic challenge
293 protocol known as "SYN cookies" to enable legitimate users to
294 continue to connect, even when your machine is under attack. There
295 is no need for the legitimate users to change their TCP/IP software;
296 SYN cookies work transparently to them. For technical information
297 about SYN cookies, check out <http://cr.yp.to/syncookies.html>.
299 If you are SYN flooded, the source address reported by the kernel is
300 likely to have been forged by the attacker; it is only reported as
301 an aid in tracing the packets to their actual source and should not
302 be taken as absolute truth.
304 SYN cookies may prevent correct error reporting on clients when the
305 server is really overloaded. If this happens frequently better turn
308 If you say Y here, you can disable SYN cookies at run time by
309 saying Y to "/proc file system support" and
310 "Sysctl support" below and executing the command
312 echo 0 > /proc/sys/net/ipv4/tcp_syncookies
314 after the /proc file system has been mounted.
319 tristate "Virtual (secure) IP: tunneling"
321 depends on INET_XFRM_MODE_TUNNEL
323 Tunneling means encapsulating data of one protocol type within
324 another protocol and sending it over a channel that understands the
325 encapsulating protocol. This can be used with xfrm mode tunnel to give
326 the notion of a secure tunnel for IPSEC and then use routing protocol
330 tristate "IP: AH transformation"
337 Support for IPsec AH.
342 tristate "IP: ESP transformation"
345 select CRYPTO_AUTHENC
352 Support for IPsec ESP.
357 tristate "IP: IPComp transformation"
358 select INET_XFRM_TUNNEL
361 Support for IP Payload Compression Protocol (IPComp) (RFC3173),
362 typically needed for IPsec.
366 config INET_XFRM_TUNNEL
375 config INET_XFRM_MODE_TRANSPORT
376 tristate "IP: IPsec transport mode"
380 Support for IPsec transport mode.
384 config INET_XFRM_MODE_TUNNEL
385 tristate "IP: IPsec tunnel mode"
389 Support for IPsec tunnel mode.
393 config INET_XFRM_MODE_BEET
394 tristate "IP: IPsec BEET mode"
398 Support for IPsec BEET mode.
403 tristate "Large Receive Offload (ipv4/tcp)"
406 Support for Large Receive Offload (ipv4/tcp).
411 tristate "INET: socket monitoring interface"
414 Support for INET (TCP, DCCP, etc) socket monitoring interface used by
415 native Linux tools such as ss. ss is included in iproute2, currently
418 http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2
424 def_tristate INET_DIAG
427 tristate "UDP: socket monitoring interface"
428 depends on INET_DIAG && (IPV6 || IPV6=n)
431 Support for UDP socket monitoring interface used by the ss tool.
434 menuconfig TCP_CONG_ADVANCED
435 bool "TCP: advanced congestion control"
437 Support for selection of various TCP congestion control
440 Nearly all users can safely say no here, and a safe default
441 selection will be made (CUBIC with new Reno as a fallback).
448 tristate "Binary Increase Congestion (BIC) control"
451 BIC-TCP is a sender-side only change that ensures a linear RTT
452 fairness under large windows while offering both scalability and
453 bounded TCP-friendliness. The protocol combines two schemes
454 called additive increase and binary search increase. When the
455 congestion window is large, additive increase with a large
456 increment ensures linear RTT fairness as well as good
457 scalability. Under small congestion windows, binary search
458 increase provides TCP friendliness.
459 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
461 config TCP_CONG_CUBIC
465 This is version 2.0 of BIC-TCP which uses a cubic growth function
466 among other techniques.
467 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
469 config TCP_CONG_WESTWOOD
470 tristate "TCP Westwood+"
473 TCP Westwood+ is a sender-side only modification of the TCP Reno
474 protocol stack that optimizes the performance of TCP congestion
475 control. It is based on end-to-end bandwidth estimation to set
476 congestion window and slow start threshold after a congestion
477 episode. Using this estimation, TCP Westwood+ adaptively sets a
478 slow start threshold and a congestion window which takes into
479 account the bandwidth used at the time congestion is experienced.
480 TCP Westwood+ significantly increases fairness wrt TCP Reno in
481 wired networks and throughput over wireless links.
487 H-TCP is a send-side only modifications of the TCP Reno
488 protocol stack that optimizes the performance of TCP
489 congestion control for high speed network links. It uses a
490 modeswitch to change the alpha and beta parameters of TCP Reno
491 based on network conditions and in a way so as to be fair with
492 other Reno and H-TCP flows.
494 config TCP_CONG_HSTCP
495 tristate "High Speed TCP"
498 Sally Floyd's High Speed TCP (RFC 3649) congestion control.
499 A modification to TCP's congestion control mechanism for use
500 with large congestion windows. A table indicates how much to
501 increase the congestion window by when an ACK is received.
502 For more detail see http://www.icir.org/floyd/hstcp.html
504 config TCP_CONG_HYBLA
505 tristate "TCP-Hybla congestion control algorithm"
508 TCP-Hybla is a sender-side only change that eliminates penalization of
509 long-RTT, large-bandwidth connections, like when satellite legs are
510 involved, especially when sharing a common bottleneck with normal
511 terrestrial connections.
513 config TCP_CONG_VEGAS
517 TCP Vegas is a sender-side only change to TCP that anticipates
518 the onset of congestion by estimating the bandwidth. TCP Vegas
519 adjusts the sending rate by modifying the congestion
520 window. TCP Vegas should provide less packet loss, but it is
521 not as aggressive as TCP Reno.
523 config TCP_CONG_SCALABLE
524 tristate "Scalable TCP"
527 Scalable TCP is a sender-side only change to TCP which uses a
528 MIMD congestion control algorithm which has some nice scaling
529 properties, though is known to have fairness issues.
530 See http://www.deneholme.net/tom/scalable/
533 tristate "TCP Low Priority"
536 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
537 to utilize only the excess network bandwidth as compared to the
538 ``fair share`` of bandwidth as targeted by TCP.
539 See http://www-ece.rice.edu/networks/TCP-LP/
545 TCP Veno is a sender-side only enhancement of TCP to obtain better
546 throughput over wireless networks. TCP Veno makes use of state
547 distinguishing to circumvent the difficult judgment of the packet loss
548 type. TCP Veno cuts down less congestion window in response to random
550 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
554 select TCP_CONG_VEGAS
557 YeAH-TCP is a sender-side high-speed enabled TCP congestion control
558 algorithm, which uses a mixed loss/delay approach to compute the
559 congestion window. It's design goals target high efficiency,
560 internal, RTT and Reno fairness, resilience to link loss while
561 keeping network elements load as low as possible.
563 For further details look here:
564 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
566 config TCP_CONG_ILLINOIS
567 tristate "TCP Illinois"
570 TCP-Illinois is a sender-side modification of TCP Reno for
571 high speed long delay links. It uses round-trip-time to
572 adjust the alpha and beta parameters to achieve a higher average
573 throughput and maintain fairness.
575 For further details see:
576 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
579 prompt "Default TCP congestion control"
580 default DEFAULT_CUBIC
582 Select the TCP congestion control that will be used by default
586 bool "Bic" if TCP_CONG_BIC=y
589 bool "Cubic" if TCP_CONG_CUBIC=y
592 bool "Htcp" if TCP_CONG_HTCP=y
595 bool "Hybla" if TCP_CONG_HYBLA=y
598 bool "Vegas" if TCP_CONG_VEGAS=y
601 bool "Veno" if TCP_CONG_VENO=y
603 config DEFAULT_WESTWOOD
604 bool "Westwood" if TCP_CONG_WESTWOOD=y
613 config TCP_CONG_CUBIC
615 depends on !TCP_CONG_ADVANCED
618 config DEFAULT_TCP_CONG
620 default "bic" if DEFAULT_BIC
621 default "cubic" if DEFAULT_CUBIC
622 default "htcp" if DEFAULT_HTCP
623 default "hybla" if DEFAULT_HYBLA
624 default "vegas" if DEFAULT_VEGAS
625 default "westwood" if DEFAULT_WESTWOOD
626 default "veno" if DEFAULT_VENO
627 default "reno" if DEFAULT_RENO
631 bool "TCP: MD5 Signature Option support (RFC2385)"
635 RFC2385 specifies a method of giving MD5 protection to TCP sessions.
636 Its main (only?) use is to protect BGP sessions between core routers