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"
322 depends on INET_XFRM_MODE_TUNNEL
324 Tunneling means encapsulating data of one protocol type within
325 another protocol and sending it over a channel that understands the
326 encapsulating protocol. This can be used with xfrm mode tunnel to give
327 the notion of a secure tunnel for IPSEC and then use routing protocol
331 tristate "IP: AH transformation"
338 Support for IPsec AH.
343 tristate "IP: ESP transformation"
346 select CRYPTO_AUTHENC
353 Support for IPsec ESP.
358 tristate "IP: IPComp transformation"
359 select INET_XFRM_TUNNEL
362 Support for IP Payload Compression Protocol (IPComp) (RFC3173),
363 typically needed for IPsec.
367 config INET_XFRM_TUNNEL
376 config INET_XFRM_MODE_TRANSPORT
377 tristate "IP: IPsec transport mode"
381 Support for IPsec transport mode.
385 config INET_XFRM_MODE_TUNNEL
386 tristate "IP: IPsec tunnel mode"
390 Support for IPsec tunnel mode.
394 config INET_XFRM_MODE_BEET
395 tristate "IP: IPsec BEET mode"
399 Support for IPsec BEET mode.
404 tristate "Large Receive Offload (ipv4/tcp)"
407 Support for Large Receive Offload (ipv4/tcp).
412 tristate "INET: socket monitoring interface"
415 Support for INET (TCP, DCCP, etc) socket monitoring interface used by
416 native Linux tools such as ss. ss is included in iproute2, currently
419 http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2
425 def_tristate INET_DIAG
428 tristate "UDP: socket monitoring interface"
429 depends on INET_DIAG && (IPV6 || IPV6=n)
432 Support for UDP socket monitoring interface used by the ss tool.
435 menuconfig TCP_CONG_ADVANCED
436 bool "TCP: advanced congestion control"
438 Support for selection of various TCP congestion control
441 Nearly all users can safely say no here, and a safe default
442 selection will be made (CUBIC with new Reno as a fallback).
449 tristate "Binary Increase Congestion (BIC) control"
452 BIC-TCP is a sender-side only change that ensures a linear RTT
453 fairness under large windows while offering both scalability and
454 bounded TCP-friendliness. The protocol combines two schemes
455 called additive increase and binary search increase. When the
456 congestion window is large, additive increase with a large
457 increment ensures linear RTT fairness as well as good
458 scalability. Under small congestion windows, binary search
459 increase provides TCP friendliness.
460 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
462 config TCP_CONG_CUBIC
466 This is version 2.0 of BIC-TCP which uses a cubic growth function
467 among other techniques.
468 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
470 config TCP_CONG_WESTWOOD
471 tristate "TCP Westwood+"
474 TCP Westwood+ is a sender-side only modification of the TCP Reno
475 protocol stack that optimizes the performance of TCP congestion
476 control. It is based on end-to-end bandwidth estimation to set
477 congestion window and slow start threshold after a congestion
478 episode. Using this estimation, TCP Westwood+ adaptively sets a
479 slow start threshold and a congestion window which takes into
480 account the bandwidth used at the time congestion is experienced.
481 TCP Westwood+ significantly increases fairness wrt TCP Reno in
482 wired networks and throughput over wireless links.
488 H-TCP is a send-side only modifications of the TCP Reno
489 protocol stack that optimizes the performance of TCP
490 congestion control for high speed network links. It uses a
491 modeswitch to change the alpha and beta parameters of TCP Reno
492 based on network conditions and in a way so as to be fair with
493 other Reno and H-TCP flows.
495 config TCP_CONG_HSTCP
496 tristate "High Speed TCP"
499 Sally Floyd's High Speed TCP (RFC 3649) congestion control.
500 A modification to TCP's congestion control mechanism for use
501 with large congestion windows. A table indicates how much to
502 increase the congestion window by when an ACK is received.
503 For more detail see http://www.icir.org/floyd/hstcp.html
505 config TCP_CONG_HYBLA
506 tristate "TCP-Hybla congestion control algorithm"
509 TCP-Hybla is a sender-side only change that eliminates penalization of
510 long-RTT, large-bandwidth connections, like when satellite legs are
511 involved, especially when sharing a common bottleneck with normal
512 terrestrial connections.
514 config TCP_CONG_VEGAS
518 TCP Vegas is a sender-side only change to TCP that anticipates
519 the onset of congestion by estimating the bandwidth. TCP Vegas
520 adjusts the sending rate by modifying the congestion
521 window. TCP Vegas should provide less packet loss, but it is
522 not as aggressive as TCP Reno.
524 config TCP_CONG_SCALABLE
525 tristate "Scalable TCP"
528 Scalable TCP is a sender-side only change to TCP which uses a
529 MIMD congestion control algorithm which has some nice scaling
530 properties, though is known to have fairness issues.
531 See http://www.deneholme.net/tom/scalable/
534 tristate "TCP Low Priority"
537 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
538 to utilize only the excess network bandwidth as compared to the
539 ``fair share`` of bandwidth as targeted by TCP.
540 See http://www-ece.rice.edu/networks/TCP-LP/
546 TCP Veno is a sender-side only enhancement of TCP to obtain better
547 throughput over wireless networks. TCP Veno makes use of state
548 distinguishing to circumvent the difficult judgment of the packet loss
549 type. TCP Veno cuts down less congestion window in response to random
551 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
555 select TCP_CONG_VEGAS
558 YeAH-TCP is a sender-side high-speed enabled TCP congestion control
559 algorithm, which uses a mixed loss/delay approach to compute the
560 congestion window. It's design goals target high efficiency,
561 internal, RTT and Reno fairness, resilience to link loss while
562 keeping network elements load as low as possible.
564 For further details look here:
565 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
567 config TCP_CONG_ILLINOIS
568 tristate "TCP Illinois"
571 TCP-Illinois is a sender-side modification of TCP Reno for
572 high speed long delay links. It uses round-trip-time to
573 adjust the alpha and beta parameters to achieve a higher average
574 throughput and maintain fairness.
576 For further details see:
577 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
580 prompt "Default TCP congestion control"
581 default DEFAULT_CUBIC
583 Select the TCP congestion control that will be used by default
587 bool "Bic" if TCP_CONG_BIC=y
590 bool "Cubic" if TCP_CONG_CUBIC=y
593 bool "Htcp" if TCP_CONG_HTCP=y
596 bool "Hybla" if TCP_CONG_HYBLA=y
599 bool "Vegas" if TCP_CONG_VEGAS=y
602 bool "Veno" if TCP_CONG_VENO=y
604 config DEFAULT_WESTWOOD
605 bool "Westwood" if TCP_CONG_WESTWOOD=y
614 config TCP_CONG_CUBIC
616 depends on !TCP_CONG_ADVANCED
619 config DEFAULT_TCP_CONG
621 default "bic" if DEFAULT_BIC
622 default "cubic" if DEFAULT_CUBIC
623 default "htcp" if DEFAULT_HTCP
624 default "hybla" if DEFAULT_HYBLA
625 default "vegas" if DEFAULT_VEGAS
626 default "westwood" if DEFAULT_WESTWOOD
627 default "veno" if DEFAULT_VENO
628 default "reno" if DEFAULT_RENO
632 bool "TCP: MD5 Signature Option support (RFC2385)"
636 RFC2385 specifies a method of giving MD5 protection to TCP sessions.
637 Its main (only?) use is to protect BGP sessions between core routers