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/>. For most people, it's safe to say N.
14 config IP_ADVANCED_ROUTER
15 bool "IP: advanced router"
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.
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.
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
31 echo "1" > /proc/sys/net/ipv4/ip_forward
33 at boot time after the /proc file system has been mounted.
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
45 echo 1 > /proc/sys/net/ipv4/conf/<device>/rp_filter
47 echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
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>.
53 If unsure, say N here.
55 config IP_FIB_TRIE_STATS
56 bool "FIB TRIE statistics"
57 depends on IP_ADVANCED_ROUTER
59 Keep track of statistics on structure of FIB TRIE table.
60 Useful for testing and measuring TRIE performance.
62 config IP_MULTIPLE_TABLES
63 bool "IP: policy routing"
64 depends on IP_ADVANCED_ROUTER
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.
73 If you need more information, see the Linux Advanced
74 Routing and Traffic Control documentation at
75 <http://lartc.org/howto/lartc.rpdb.html>
79 config IP_ROUTE_MULTIPATH
80 bool "IP: equal cost multipath"
81 depends on IP_ADVANCED_ROUTER
83 Normally, the routing tables specify a single action to be taken in
84 a deterministic manner for a given packet. If you say Y here
85 however, it becomes possible to attach several actions to a packet
86 pattern, in effect specifying several alternative paths to travel
87 for those packets. The router considers all these paths to be of
88 equal "cost" and chooses one of them in a non-deterministic fashion
89 if a matching packet arrives.
91 config IP_ROUTE_VERBOSE
92 bool "IP: verbose route monitoring"
93 depends on IP_ADVANCED_ROUTER
95 If you say Y here, which is recommended, then the kernel will print
96 verbose messages regarding the routing, for example warnings about
97 received packets which look strange and could be evidence of an
98 attack or a misconfigured system somewhere. The information is
99 handled by the klogd daemon which is responsible for kernel messages
102 config IP_ROUTE_CLASSID
106 bool "IP: kernel level autoconfiguration"
108 This enables automatic configuration of IP addresses of devices and
109 of the routing table during kernel boot, based on either information
110 supplied on the kernel command line or by BOOTP or RARP protocols.
111 You need to say Y only for diskless machines requiring network
112 access to boot (in which case you want to say Y to "Root file system
113 on NFS" as well), because all other machines configure the network
114 in their startup scripts.
117 bool "IP: DHCP support"
120 If you want your Linux box to mount its whole root file system (the
121 one containing the directory /) from some other computer over the
122 net via NFS and you want the IP address of your computer to be
123 discovered automatically at boot time using the DHCP protocol (a
124 special protocol designed for doing this job), say Y here. In case
125 the boot ROM of your network card was designed for booting Linux and
126 does DHCP itself, providing all necessary information on the kernel
127 command line, you can say N here.
129 If unsure, say Y. Note that if you want to use DHCP, a DHCP server
130 must be operating on your network. Read
131 <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
134 bool "IP: BOOTP support"
137 If you want your Linux box to mount its whole root file system (the
138 one containing the directory /) from some other computer over the
139 net via NFS and you want the IP address of your computer to be
140 discovered automatically at boot time using the BOOTP protocol (a
141 special protocol designed for doing this job), say Y here. In case
142 the boot ROM of your network card was designed for booting Linux and
143 does BOOTP itself, providing all necessary information on the kernel
144 command line, you can say N here. If unsure, say Y. Note that if you
145 want to use BOOTP, a BOOTP server must be operating on your network.
146 Read <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
149 bool "IP: RARP support"
152 If you want your Linux box to mount its whole root file system (the
153 one containing the directory /) from some other computer over the
154 net via NFS and you want the IP address of your computer to be
155 discovered automatically at boot time using the RARP protocol (an
156 older protocol which is being obsoleted by BOOTP and DHCP), say Y
157 here. Note that if you want to use RARP, a RARP server must be
158 operating on your network. Read
159 <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
162 tristate "IP: tunneling"
166 Tunneling means encapsulating data of one protocol type within
167 another protocol and sending it over a channel that understands the
168 encapsulating protocol. This particular tunneling driver implements
169 encapsulation of IP within IP, which sounds kind of pointless, but
170 can be useful if you want to make your (or some other) machine
171 appear on a different network than it physically is, or to use
172 mobile-IP facilities (allowing laptops to seamlessly move between
173 networks without changing their IP addresses).
175 Saying Y to this option will produce two modules ( = code which can
176 be inserted in and removed from the running kernel whenever you
177 want). Most people won't need this and can say N.
179 config NET_IPGRE_DEMUX
180 tristate "IP: GRE demultiplexer"
182 This is helper module to demultiplex GRE packets on GRE version field criteria.
183 Required by ip_gre and pptp modules.
192 tristate "IP: GRE tunnels over IP"
193 depends on (IPV6 || IPV6=n) && NET_IPGRE_DEMUX
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
206 config NET_IPGRE_BROADCAST
207 bool "IP: broadcast GRE over IP"
208 depends on IP_MULTICAST && NET_IPGRE
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.
216 bool "IP: multicast routing"
217 depends on IP_MULTICAST
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
226 config IP_MROUTE_MULTIPLE_TABLES
227 bool "IP: multicast policy routing"
228 depends on IP_MROUTE && IP_ADVANCED_ROUTER
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.
241 bool "IP: PIM-SM version 1 support"
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.
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.
254 bool "IP: PIM-SM version 2 support"
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.
263 bool "IP: TCP syncookie support"
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.
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>.
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.
284 SYN cookies may prevent correct error reporting on clients when the
285 server is really overloaded. If this happens frequently better turn
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
292 echo 0 > /proc/sys/net/ipv4/tcp_syncookies
294 after the /proc file system has been mounted.
299 tristate "Virtual (secure) IP: tunneling"
302 depends on INET_XFRM_MODE_TUNNEL
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
310 config NET_UDP_TUNNEL
316 tristate "IP: Foo (IP protocols) over UDP"
318 select NET_UDP_TUNNEL
320 Foo over UDP allows any IP protocol to be directly encapsulated
321 over UDP include tunnels (IPIP, GRE, SIT). By encapsulating in UDP
322 network mechanisms and optimizations for UDP (such as ECMP
323 and RSS) can be leveraged to provide better service.
325 config NET_FOU_IP_TUNNELS
326 bool "IP: FOU encapsulation of IP tunnels"
327 depends on NET_IPIP || NET_IPGRE || IPV6_SIT
330 Allow configuration of FOU or GUE encapsulation for IP tunnels.
331 When this option is enabled IP tunnels can be configured to use
332 FOU or GUE encapsulation.
335 tristate "IP: AH transformation"
342 Support for IPsec AH.
347 tristate "IP: ESP transformation"
350 select CRYPTO_AUTHENC
356 select CRYPTO_ECHAINIV
358 Support for IPsec ESP.
362 config INET_ESP_OFFLOAD
363 tristate "IP: ESP transformation offload"
368 Support for ESP transformation offload. This makes sense
369 only if this system really does IPsec and want to do it
370 with high throughput. A typical desktop system does not
371 need it, even if it does IPsec.
376 tristate "IP: IPComp transformation"
377 select INET_XFRM_TUNNEL
380 Support for IP Payload Compression Protocol (IPComp) (RFC3173),
381 typically needed for IPsec.
385 config INET_XFRM_TUNNEL
394 config INET_XFRM_MODE_TRANSPORT
395 tristate "IP: IPsec transport mode"
399 Support for IPsec transport mode.
403 config INET_XFRM_MODE_TUNNEL
404 tristate "IP: IPsec tunnel mode"
408 Support for IPsec tunnel mode.
412 config INET_XFRM_MODE_BEET
413 tristate "IP: IPsec BEET mode"
417 Support for IPsec BEET mode.
422 tristate "INET: socket monitoring interface"
425 Support for INET (TCP, DCCP, etc) socket monitoring interface used by
426 native Linux tools such as ss. ss is included in iproute2, currently
429 http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2
435 def_tristate INET_DIAG
438 tristate "UDP: socket monitoring interface"
439 depends on INET_DIAG && (IPV6 || IPV6=n)
442 Support for UDP socket monitoring interface used by the ss tool.
446 tristate "RAW: socket monitoring interface"
447 depends on INET_DIAG && (IPV6 || IPV6=n)
450 Support for RAW socket monitoring interface used by the ss tool.
453 config INET_DIAG_DESTROY
454 bool "INET: allow privileged process to administratively close sockets"
458 Provides a SOCK_DESTROY operation that allows privileged processes
459 (e.g., a connection manager or a network administration tool such as
460 ss) to close sockets opened by other processes. Closing a socket in
461 this way interrupts any blocking read/write/connect operations on
462 the socket and causes future socket calls to behave as if the socket
463 had been disconnected.
466 menuconfig TCP_CONG_ADVANCED
467 bool "TCP: advanced congestion control"
469 Support for selection of various TCP congestion control
472 Nearly all users can safely say no here, and a safe default
473 selection will be made (CUBIC with new Reno as a fallback).
480 tristate "Binary Increase Congestion (BIC) control"
483 BIC-TCP is a sender-side only change that ensures a linear RTT
484 fairness under large windows while offering both scalability and
485 bounded TCP-friendliness. The protocol combines two schemes
486 called additive increase and binary search increase. When the
487 congestion window is large, additive increase with a large
488 increment ensures linear RTT fairness as well as good
489 scalability. Under small congestion windows, binary search
490 increase provides TCP friendliness.
491 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
493 config TCP_CONG_CUBIC
497 This is version 2.0 of BIC-TCP which uses a cubic growth function
498 among other techniques.
499 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
501 config TCP_CONG_WESTWOOD
502 tristate "TCP Westwood+"
505 TCP Westwood+ is a sender-side only modification of the TCP Reno
506 protocol stack that optimizes the performance of TCP congestion
507 control. It is based on end-to-end bandwidth estimation to set
508 congestion window and slow start threshold after a congestion
509 episode. Using this estimation, TCP Westwood+ adaptively sets a
510 slow start threshold and a congestion window which takes into
511 account the bandwidth used at the time congestion is experienced.
512 TCP Westwood+ significantly increases fairness wrt TCP Reno in
513 wired networks and throughput over wireless links.
519 H-TCP is a send-side only modifications of the TCP Reno
520 protocol stack that optimizes the performance of TCP
521 congestion control for high speed network links. It uses a
522 modeswitch to change the alpha and beta parameters of TCP Reno
523 based on network conditions and in a way so as to be fair with
524 other Reno and H-TCP flows.
526 config TCP_CONG_HSTCP
527 tristate "High Speed TCP"
530 Sally Floyd's High Speed TCP (RFC 3649) congestion control.
531 A modification to TCP's congestion control mechanism for use
532 with large congestion windows. A table indicates how much to
533 increase the congestion window by when an ACK is received.
534 For more detail see http://www.icir.org/floyd/hstcp.html
536 config TCP_CONG_HYBLA
537 tristate "TCP-Hybla congestion control algorithm"
540 TCP-Hybla is a sender-side only change that eliminates penalization of
541 long-RTT, large-bandwidth connections, like when satellite legs are
542 involved, especially when sharing a common bottleneck with normal
543 terrestrial connections.
545 config TCP_CONG_VEGAS
549 TCP Vegas is a sender-side only change to TCP that anticipates
550 the onset of congestion by estimating the bandwidth. TCP Vegas
551 adjusts the sending rate by modifying the congestion
552 window. TCP Vegas should provide less packet loss, but it is
553 not as aggressive as TCP Reno.
559 TCP NV is a follow up to TCP Vegas. It has been modified to deal with
560 10G networks, measurement noise introduced by LRO, GRO and interrupt
561 coalescence. In addition, it will decrease its cwnd multiplicatively
564 Note that in general congestion avoidance (cwnd decreased when # packets
565 queued grows) cannot coexist with congestion control (cwnd decreased only
566 when there is packet loss) due to fairness issues. One scenario when they
567 can coexist safely is when the CA flows have RTTs << CC flows RTTs.
569 For further details see http://www.brakmo.org/networking/tcp-nv/
571 config TCP_CONG_SCALABLE
572 tristate "Scalable TCP"
575 Scalable TCP is a sender-side only change to TCP which uses a
576 MIMD congestion control algorithm which has some nice scaling
577 properties, though is known to have fairness issues.
578 See http://www.deneholme.net/tom/scalable/
581 tristate "TCP Low Priority"
584 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
585 to utilize only the excess network bandwidth as compared to the
586 ``fair share`` of bandwidth as targeted by TCP.
587 See http://www-ece.rice.edu/networks/TCP-LP/
593 TCP Veno is a sender-side only enhancement of TCP to obtain better
594 throughput over wireless networks. TCP Veno makes use of state
595 distinguishing to circumvent the difficult judgment of the packet loss
596 type. TCP Veno cuts down less congestion window in response to random
598 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
602 select TCP_CONG_VEGAS
605 YeAH-TCP is a sender-side high-speed enabled TCP congestion control
606 algorithm, which uses a mixed loss/delay approach to compute the
607 congestion window. It's design goals target high efficiency,
608 internal, RTT and Reno fairness, resilience to link loss while
609 keeping network elements load as low as possible.
611 For further details look here:
612 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
614 config TCP_CONG_ILLINOIS
615 tristate "TCP Illinois"
618 TCP-Illinois is a sender-side modification of TCP Reno for
619 high speed long delay links. It uses round-trip-time to
620 adjust the alpha and beta parameters to achieve a higher average
621 throughput and maintain fairness.
623 For further details see:
624 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
626 config TCP_CONG_DCTCP
627 tristate "DataCenter TCP (DCTCP)"
630 DCTCP leverages Explicit Congestion Notification (ECN) in the network to
631 provide multi-bit feedback to the end hosts. It is designed to provide:
633 - High burst tolerance (incast due to partition/aggregate),
634 - Low latency (short flows, queries),
635 - High throughput (continuous data updates, large file transfers) with
636 commodity, shallow-buffered switches.
638 All switches in the data center network running DCTCP must support
639 ECN marking and be configured for marking when reaching defined switch
640 buffer thresholds. The default ECN marking threshold heuristic for
641 DCTCP on switches is 20 packets (30KB) at 1Gbps, and 65 packets
642 (~100KB) at 10Gbps, but might need further careful tweaking.
644 For further details see:
645 http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
648 tristate "CAIA Delay-Gradient (CDG)"
651 CAIA Delay-Gradient (CDG) is a TCP congestion control that modifies
652 the TCP sender in order to:
654 o Use the delay gradient as a congestion signal.
655 o Back off with an average probability that is independent of the RTT.
656 o Coexist with flows that use loss-based congestion control.
657 o Tolerate packet loss unrelated to congestion.
659 For further details see:
660 D.A. Hayes and G. Armitage. "Revisiting TCP congestion control using
661 delay gradients." In Networking 2011. Preprint: http://goo.gl/No3vdg
668 BBR (Bottleneck Bandwidth and RTT) TCP congestion control aims to
669 maximize network utilization and minimize queues. It builds an explicit
670 model of the the bottleneck delivery rate and path round-trip
671 propagation delay. It tolerates packet loss and delay unrelated to
672 congestion. It can operate over LAN, WAN, cellular, wifi, or cable
673 modem links. It can coexist with flows that use loss-based congestion
674 control, and can operate with shallow buffers, deep buffers,
675 bufferbloat, policers, or AQM schemes that do not provide a delay
676 signal. It requires the fq ("Fair Queue") pacing packet scheduler.
679 prompt "Default TCP congestion control"
680 default DEFAULT_CUBIC
682 Select the TCP congestion control that will be used by default
686 bool "Bic" if TCP_CONG_BIC=y
689 bool "Cubic" if TCP_CONG_CUBIC=y
692 bool "Htcp" if TCP_CONG_HTCP=y
695 bool "Hybla" if TCP_CONG_HYBLA=y
698 bool "Vegas" if TCP_CONG_VEGAS=y
701 bool "Veno" if TCP_CONG_VENO=y
703 config DEFAULT_WESTWOOD
704 bool "Westwood" if TCP_CONG_WESTWOOD=y
707 bool "DCTCP" if TCP_CONG_DCTCP=y
710 bool "CDG" if TCP_CONG_CDG=y
713 bool "BBR" if TCP_CONG_BBR=y
721 config TCP_CONG_CUBIC
723 depends on !TCP_CONG_ADVANCED
726 config DEFAULT_TCP_CONG
728 default "bic" if DEFAULT_BIC
729 default "cubic" if DEFAULT_CUBIC
730 default "htcp" if DEFAULT_HTCP
731 default "hybla" if DEFAULT_HYBLA
732 default "vegas" if DEFAULT_VEGAS
733 default "westwood" if DEFAULT_WESTWOOD
734 default "veno" if DEFAULT_VENO
735 default "reno" if DEFAULT_RENO
736 default "dctcp" if DEFAULT_DCTCP
737 default "cdg" if DEFAULT_CDG
738 default "bbr" if DEFAULT_BBR
742 bool "TCP: MD5 Signature Option support (RFC2385)"
746 RFC2385 specifies a method of giving MD5 protection to TCP sessions.
747 Its main (only?) use is to protect BGP sessions between core routers