1 # SPDX-License-Identifier: GPL-2.0-only
6 bool "IP: multicasting"
8 This is code for addressing several networked computers at once,
9 enlarging your kernel by about 2 KB. You need multicasting if you
10 intend to participate in the MBONE, a high bandwidth network on top
11 of the Internet which carries audio and video broadcasts. More
12 information about the MBONE is on the WWW at
13 <https://www.savetz.com/mbone/>. For most people, it's safe to say N.
15 config IP_ADVANCED_ROUTER
16 bool "IP: advanced router"
18 If you intend to run your Linux box mostly as a router, i.e. as a
19 computer that forwards and redistributes network packets, say Y; you
20 will then be presented with several options that allow more precise
21 control about the routing process.
23 The answer to this question won't directly affect the kernel:
24 answering N will just cause the configurator to skip all the
25 questions about advanced routing.
27 Note that your box can only act as a router if you enable IP
28 forwarding in your kernel; you can do that by saying Y to "/proc
29 file system support" and "Sysctl support" below and executing the
32 echo "1" > /proc/sys/net/ipv4/ip_forward
34 at boot time after the /proc file system has been mounted.
36 If you turn on IP forwarding, you should consider the rp_filter, which
37 automatically rejects incoming packets if the routing table entry
38 for their source address doesn't match the network interface they're
39 arriving on. This has security advantages because it prevents the
40 so-called IP spoofing, however it can pose problems if you use
41 asymmetric routing (packets from you to a host take a different path
42 than packets from that host to you) or if you operate a non-routing
43 host which has several IP addresses on different interfaces. To turn
46 echo 1 > /proc/sys/net/ipv4/conf/<device>/rp_filter
48 echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
50 Note that some distributions enable it in startup scripts.
51 For details about rp_filter strict and loose mode read
52 <file:Documentation/networking/ip-sysctl.rst>.
54 If unsure, say N here.
56 config IP_FIB_TRIE_STATS
57 bool "FIB TRIE statistics"
58 depends on IP_ADVANCED_ROUTER
60 Keep track of statistics on structure of FIB TRIE table.
61 Useful for testing and measuring TRIE performance.
63 config IP_MULTIPLE_TABLES
64 bool "IP: policy routing"
65 depends on IP_ADVANCED_ROUTER
68 Normally, a router decides what to do with a received packet based
69 solely on the packet's final destination address. If you say Y here,
70 the Linux router will also be able to take the packet's source
71 address into account. Furthermore, the TOS (Type-Of-Service) field
72 of the packet can be used for routing decisions as well.
74 If you need more information, see the Linux Advanced
75 Routing and Traffic Control documentation at
76 <https://lartc.org/howto/lartc.rpdb.html>
80 config IP_ROUTE_MULTIPATH
81 bool "IP: equal cost multipath"
82 depends on IP_ADVANCED_ROUTER
84 Normally, the routing tables specify a single action to be taken in
85 a deterministic manner for a given packet. If you say Y here
86 however, it becomes possible to attach several actions to a packet
87 pattern, in effect specifying several alternative paths to travel
88 for those packets. The router considers all these paths to be of
89 equal "cost" and chooses one of them in a non-deterministic fashion
90 if a matching packet arrives.
92 config IP_ROUTE_VERBOSE
93 bool "IP: verbose route monitoring"
94 depends on IP_ADVANCED_ROUTER
96 If you say Y here, which is recommended, then the kernel will print
97 verbose messages regarding the routing, for example warnings about
98 received packets which look strange and could be evidence of an
99 attack or a misconfigured system somewhere. The information is
100 handled by the klogd daemon which is responsible for kernel messages
103 config IP_ROUTE_CLASSID
107 bool "IP: kernel level autoconfiguration"
109 This enables automatic configuration of IP addresses of devices and
110 of the routing table during kernel boot, based on either information
111 supplied on the kernel command line or by BOOTP or RARP protocols.
112 You need to say Y only for diskless machines requiring network
113 access to boot (in which case you want to say Y to "Root file system
114 on NFS" as well), because all other machines configure the network
115 in their startup scripts.
118 bool "IP: DHCP support"
121 If you want your Linux box to mount its whole root file system (the
122 one containing the directory /) from some other computer over the
123 net via NFS and you want the IP address of your computer to be
124 discovered automatically at boot time using the DHCP protocol (a
125 special protocol designed for doing this job), say Y here. In case
126 the boot ROM of your network card was designed for booting Linux and
127 does DHCP itself, providing all necessary information on the kernel
128 command line, you can say N here.
130 If unsure, say Y. Note that if you want to use DHCP, a DHCP server
131 must be operating on your network. Read
132 <file:Documentation/admin-guide/nfs/nfsroot.rst> for details.
135 bool "IP: BOOTP support"
138 If you want your Linux box to mount its whole root file system (the
139 one containing the directory /) from some other computer over the
140 net via NFS and you want the IP address of your computer to be
141 discovered automatically at boot time using the BOOTP protocol (a
142 special protocol designed for doing this job), say Y here. In case
143 the boot ROM of your network card was designed for booting Linux and
144 does BOOTP itself, providing all necessary information on the kernel
145 command line, you can say N here. If unsure, say Y. Note that if you
146 want to use BOOTP, a BOOTP server must be operating on your network.
147 Read <file:Documentation/admin-guide/nfs/nfsroot.rst> for details.
150 bool "IP: RARP support"
153 If you want your Linux box to mount its whole root file system (the
154 one containing the directory /) from some other computer over the
155 net via NFS and you want the IP address of your computer to be
156 discovered automatically at boot time using the RARP protocol (an
157 older protocol which is being obsoleted by BOOTP and DHCP), say Y
158 here. Note that if you want to use RARP, a RARP server must be
159 operating on your network. Read
160 <file:Documentation/admin-guide/nfs/nfsroot.rst> for details.
163 tristate "IP: tunneling"
167 Tunneling means encapsulating data of one protocol type within
168 another protocol and sending it over a channel that understands the
169 encapsulating protocol. This particular tunneling driver implements
170 encapsulation of IP within IP, which sounds kind of pointless, but
171 can be useful if you want to make your (or some other) machine
172 appear on a different network than it physically is, or to use
173 mobile-IP facilities (allowing laptops to seamlessly move between
174 networks without changing their IP addresses).
176 Saying Y to this option will produce two modules ( = code which can
177 be inserted in and removed from the running kernel whenever you
178 want). Most people won't need this and can say N.
180 config NET_IPGRE_DEMUX
181 tristate "IP: GRE demultiplexer"
183 This is helper module to demultiplex GRE packets on GRE version field criteria.
184 Required by ip_gre and pptp modules.
193 tristate "IP: GRE tunnels over IP"
194 depends on (IPV6 || IPV6=n) && NET_IPGRE_DEMUX
197 Tunneling means encapsulating data of one protocol type within
198 another protocol and sending it over a channel that understands the
199 encapsulating protocol. This particular tunneling driver implements
200 GRE (Generic Routing Encapsulation) and at this time allows
201 encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure.
202 This driver is useful if the other endpoint is a Cisco router: Cisco
203 likes GRE much better than the other Linux tunneling driver ("IP
204 tunneling" above). In addition, GRE allows multicast redistribution
207 config NET_IPGRE_BROADCAST
208 bool "IP: broadcast GRE over IP"
209 depends on IP_MULTICAST && NET_IPGRE
211 One application of GRE/IP is to construct a broadcast WAN (Wide Area
212 Network), which looks like a normal Ethernet LAN (Local Area
213 Network), but can be distributed all over the Internet. If you want
214 to do that, say Y here and to "IP multicast routing" below.
216 config IP_MROUTE_COMMON
218 depends on IP_MROUTE || IPV6_MROUTE
221 bool "IP: multicast routing"
222 depends on IP_MULTICAST
223 select IP_MROUTE_COMMON
225 This is used if you want your machine to act as a router for IP
226 packets that have several destination addresses. It is needed on the
227 MBONE, a high bandwidth network on top of the Internet which carries
228 audio and video broadcasts. In order to do that, you would most
229 likely run the program mrouted. If you haven't heard about it, you
232 config IP_MROUTE_MULTIPLE_TABLES
233 bool "IP: multicast policy routing"
234 depends on IP_MROUTE && IP_ADVANCED_ROUTER
237 Normally, a multicast router runs a userspace daemon and decides
238 what to do with a multicast packet based on the source and
239 destination addresses. If you say Y here, the multicast router
240 will also be able to take interfaces and packet marks into
241 account and run multiple instances of userspace daemons
242 simultaneously, each one handling a single table.
247 bool "IP: PIM-SM version 1 support"
250 Kernel side support for Sparse Mode PIM (Protocol Independent
251 Multicast) version 1. This multicast routing protocol is used widely
252 because Cisco supports it. You need special software to use it
253 (pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
254 information about PIM.
256 Say Y if you want to use PIM-SM v1. Note that you can say N here if
257 you just want to use Dense Mode PIM.
260 bool "IP: PIM-SM version 2 support"
263 Kernel side support for Sparse Mode PIM version 2. In order to use
264 this, you need an experimental routing daemon supporting it (pimd or
265 gated-5). This routing protocol is not used widely, so say N unless
266 you want to play with it.
269 bool "IP: TCP syncookie support"
271 Normal TCP/IP networking is open to an attack known as "SYN
272 flooding". This denial-of-service attack prevents legitimate remote
273 users from being able to connect to your computer during an ongoing
274 attack and requires very little work from the attacker, who can
275 operate from anywhere on the Internet.
277 SYN cookies provide protection against this type of attack. If you
278 say Y here, the TCP/IP stack will use a cryptographic challenge
279 protocol known as "SYN cookies" to enable legitimate users to
280 continue to connect, even when your machine is under attack. There
281 is no need for the legitimate users to change their TCP/IP software;
282 SYN cookies work transparently to them. For technical information
283 about SYN cookies, check out <https://cr.yp.to/syncookies.html>.
285 If you are SYN flooded, the source address reported by the kernel is
286 likely to have been forged by the attacker; it is only reported as
287 an aid in tracing the packets to their actual source and should not
288 be taken as absolute truth.
290 SYN cookies may prevent correct error reporting on clients when the
291 server is really overloaded. If this happens frequently better turn
294 If you say Y here, you can disable SYN cookies at run time by
295 saying Y to "/proc file system support" and
296 "Sysctl support" below and executing the command
298 echo 0 > /proc/sys/net/ipv4/tcp_syncookies
300 after the /proc file system has been mounted.
305 tristate "Virtual (secure) IP: tunneling"
306 depends on IPV6 || IPV6=n
311 Tunneling means encapsulating data of one protocol type within
312 another protocol and sending it over a channel that understands the
313 encapsulating protocol. This can be used with xfrm mode tunnel to give
314 the notion of a secure tunnel for IPSEC and then use routing protocol
317 config NET_UDP_TUNNEL
323 tristate "IP: Foo (IP protocols) over UDP"
324 select NET_UDP_TUNNEL
326 Foo over UDP allows any IP protocol to be directly encapsulated
327 over UDP include tunnels (IPIP, GRE, SIT). By encapsulating in UDP
328 network mechanisms and optimizations for UDP (such as ECMP
329 and RSS) can be leveraged to provide better service.
331 config NET_FOU_IP_TUNNELS
332 bool "IP: FOU encapsulation of IP tunnels"
333 depends on NET_IPIP || NET_IPGRE || IPV6_SIT
336 Allow configuration of FOU or GUE encapsulation for IP tunnels.
337 When this option is enabled IP tunnels can be configured to use
338 FOU or GUE encapsulation.
341 tristate "IP: AH transformation"
344 Support for IPsec AH (Authentication Header).
346 AH can be used with various authentication algorithms. Besides
347 enabling AH support itself, this option enables the generic
348 implementations of the algorithms that RFC 8221 lists as MUST be
349 implemented. If you need any other algorithms, you'll need to enable
350 them in the crypto API. You should also enable accelerated
351 implementations of any needed algorithms when available.
356 tristate "IP: ESP transformation"
359 Support for IPsec ESP (Encapsulating Security Payload).
361 ESP can be used with various encryption and authentication algorithms.
362 Besides enabling ESP support itself, this option enables the generic
363 implementations of the algorithms that RFC 8221 lists as MUST be
364 implemented. If you need any other algorithms, you'll need to enable
365 them in the crypto API. You should also enable accelerated
366 implementations of any needed algorithms when available.
370 config INET_ESP_OFFLOAD
371 tristate "IP: ESP transformation offload"
376 Support for ESP transformation offload. This makes sense
377 only if this system really does IPsec and want to do it
378 with high throughput. A typical desktop system does not
379 need it, even if it does IPsec.
384 bool "IP: ESP in TCP encapsulation (RFC 8229)"
385 depends on XFRM && INET_ESP
390 Support for RFC 8229 encapsulation of ESP and IKE over
396 tristate "IP: IPComp transformation"
397 select INET_XFRM_TUNNEL
400 Support for IP Payload Compression Protocol (IPComp) (RFC3173),
401 typically needed for IPsec.
405 config INET_XFRM_TUNNEL
415 tristate "INET: socket monitoring interface"
418 Support for INET (TCP, DCCP, etc) socket monitoring interface used by
419 native Linux tools such as ss. ss is included in iproute2, currently
422 http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2
428 def_tristate INET_DIAG
431 tristate "UDP: socket monitoring interface"
432 depends on INET_DIAG && (IPV6 || IPV6=n)
435 Support for UDP socket monitoring interface used by the ss tool.
439 tristate "RAW: socket monitoring interface"
440 depends on INET_DIAG && (IPV6 || IPV6=n)
443 Support for RAW socket monitoring interface used by the ss tool.
446 config INET_DIAG_DESTROY
447 bool "INET: allow privileged process to administratively close sockets"
451 Provides a SOCK_DESTROY operation that allows privileged processes
452 (e.g., a connection manager or a network administration tool such as
453 ss) to close sockets opened by other processes. Closing a socket in
454 this way interrupts any blocking read/write/connect operations on
455 the socket and causes future socket calls to behave as if the socket
456 had been disconnected.
459 menuconfig TCP_CONG_ADVANCED
460 bool "TCP: advanced congestion control"
462 Support for selection of various TCP congestion control
465 Nearly all users can safely say no here, and a safe default
466 selection will be made (CUBIC with new Reno as a fallback).
473 tristate "Binary Increase Congestion (BIC) control"
476 BIC-TCP is a sender-side only change that ensures a linear RTT
477 fairness under large windows while offering both scalability and
478 bounded TCP-friendliness. The protocol combines two schemes
479 called additive increase and binary search increase. When the
480 congestion window is large, additive increase with a large
481 increment ensures linear RTT fairness as well as good
482 scalability. Under small congestion windows, binary search
483 increase provides TCP friendliness.
484 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
486 config TCP_CONG_CUBIC
490 This is version 2.0 of BIC-TCP which uses a cubic growth function
491 among other techniques.
492 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
494 config TCP_CONG_WESTWOOD
495 tristate "TCP Westwood+"
498 TCP Westwood+ is a sender-side only modification of the TCP Reno
499 protocol stack that optimizes the performance of TCP congestion
500 control. It is based on end-to-end bandwidth estimation to set
501 congestion window and slow start threshold after a congestion
502 episode. Using this estimation, TCP Westwood+ adaptively sets a
503 slow start threshold and a congestion window which takes into
504 account the bandwidth used at the time congestion is experienced.
505 TCP Westwood+ significantly increases fairness wrt TCP Reno in
506 wired networks and throughput over wireless links.
512 H-TCP is a send-side only modifications of the TCP Reno
513 protocol stack that optimizes the performance of TCP
514 congestion control for high speed network links. It uses a
515 modeswitch to change the alpha and beta parameters of TCP Reno
516 based on network conditions and in a way so as to be fair with
517 other Reno and H-TCP flows.
519 config TCP_CONG_HSTCP
520 tristate "High Speed TCP"
523 Sally Floyd's High Speed TCP (RFC 3649) congestion control.
524 A modification to TCP's congestion control mechanism for use
525 with large congestion windows. A table indicates how much to
526 increase the congestion window by when an ACK is received.
527 For more detail see https://www.icir.org/floyd/hstcp.html
529 config TCP_CONG_HYBLA
530 tristate "TCP-Hybla congestion control algorithm"
533 TCP-Hybla is a sender-side only change that eliminates penalization of
534 long-RTT, large-bandwidth connections, like when satellite legs are
535 involved, especially when sharing a common bottleneck with normal
536 terrestrial connections.
538 config TCP_CONG_VEGAS
542 TCP Vegas is a sender-side only change to TCP that anticipates
543 the onset of congestion by estimating the bandwidth. TCP Vegas
544 adjusts the sending rate by modifying the congestion
545 window. TCP Vegas should provide less packet loss, but it is
546 not as aggressive as TCP Reno.
552 TCP NV is a follow up to TCP Vegas. It has been modified to deal with
553 10G networks, measurement noise introduced by LRO, GRO and interrupt
554 coalescence. In addition, it will decrease its cwnd multiplicatively
557 Note that in general congestion avoidance (cwnd decreased when # packets
558 queued grows) cannot coexist with congestion control (cwnd decreased only
559 when there is packet loss) due to fairness issues. One scenario when they
560 can coexist safely is when the CA flows have RTTs << CC flows RTTs.
562 For further details see http://www.brakmo.org/networking/tcp-nv/
564 config TCP_CONG_SCALABLE
565 tristate "Scalable TCP"
568 Scalable TCP is a sender-side only change to TCP which uses a
569 MIMD congestion control algorithm which has some nice scaling
570 properties, though is known to have fairness issues.
571 See http://www.deneholme.net/tom/scalable/
574 tristate "TCP Low Priority"
577 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
578 to utilize only the excess network bandwidth as compared to the
579 ``fair share`` of bandwidth as targeted by TCP.
580 See http://www-ece.rice.edu/networks/TCP-LP/
586 TCP Veno is a sender-side only enhancement of TCP to obtain better
587 throughput over wireless networks. TCP Veno makes use of state
588 distinguishing to circumvent the difficult judgment of the packet loss
589 type. TCP Veno cuts down less congestion window in response to random
591 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
595 select TCP_CONG_VEGAS
598 YeAH-TCP is a sender-side high-speed enabled TCP congestion control
599 algorithm, which uses a mixed loss/delay approach to compute the
600 congestion window. It's design goals target high efficiency,
601 internal, RTT and Reno fairness, resilience to link loss while
602 keeping network elements load as low as possible.
604 For further details look here:
605 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
607 config TCP_CONG_ILLINOIS
608 tristate "TCP Illinois"
611 TCP-Illinois is a sender-side modification of TCP Reno for
612 high speed long delay links. It uses round-trip-time to
613 adjust the alpha and beta parameters to achieve a higher average
614 throughput and maintain fairness.
616 For further details see:
617 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
619 config TCP_CONG_DCTCP
620 tristate "DataCenter TCP (DCTCP)"
623 DCTCP leverages Explicit Congestion Notification (ECN) in the network to
624 provide multi-bit feedback to the end hosts. It is designed to provide:
626 - High burst tolerance (incast due to partition/aggregate),
627 - Low latency (short flows, queries),
628 - High throughput (continuous data updates, large file transfers) with
629 commodity, shallow-buffered switches.
631 All switches in the data center network running DCTCP must support
632 ECN marking and be configured for marking when reaching defined switch
633 buffer thresholds. The default ECN marking threshold heuristic for
634 DCTCP on switches is 20 packets (30KB) at 1Gbps, and 65 packets
635 (~100KB) at 10Gbps, but might need further careful tweaking.
637 For further details see:
638 http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
641 tristate "CAIA Delay-Gradient (CDG)"
644 CAIA Delay-Gradient (CDG) is a TCP congestion control that modifies
645 the TCP sender in order to:
647 o Use the delay gradient as a congestion signal.
648 o Back off with an average probability that is independent of the RTT.
649 o Coexist with flows that use loss-based congestion control.
650 o Tolerate packet loss unrelated to congestion.
652 For further details see:
653 D.A. Hayes and G. Armitage. "Revisiting TCP congestion control using
654 delay gradients." In Networking 2011. Preprint: http://goo.gl/No3vdg
661 BBR (Bottleneck Bandwidth and RTT) TCP congestion control aims to
662 maximize network utilization and minimize queues. It builds an explicit
663 model of the bottleneck delivery rate and path round-trip propagation
664 delay. It tolerates packet loss and delay unrelated to congestion. It
665 can operate over LAN, WAN, cellular, wifi, or cable modem links. It can
666 coexist with flows that use loss-based congestion control, and can
667 operate with shallow buffers, deep buffers, bufferbloat, policers, or
668 AQM schemes that do not provide a delay signal. It requires the fq
669 ("Fair Queue") pacing packet scheduler.
672 prompt "Default TCP congestion control"
673 default DEFAULT_CUBIC
675 Select the TCP congestion control that will be used by default
679 bool "Bic" if TCP_CONG_BIC=y
682 bool "Cubic" if TCP_CONG_CUBIC=y
685 bool "Htcp" if TCP_CONG_HTCP=y
688 bool "Hybla" if TCP_CONG_HYBLA=y
691 bool "Vegas" if TCP_CONG_VEGAS=y
694 bool "Veno" if TCP_CONG_VENO=y
696 config DEFAULT_WESTWOOD
697 bool "Westwood" if TCP_CONG_WESTWOOD=y
700 bool "DCTCP" if TCP_CONG_DCTCP=y
703 bool "CDG" if TCP_CONG_CDG=y
706 bool "BBR" if TCP_CONG_BBR=y
714 config TCP_CONG_CUBIC
716 depends on !TCP_CONG_ADVANCED
719 config DEFAULT_TCP_CONG
721 default "bic" if DEFAULT_BIC
722 default "cubic" if DEFAULT_CUBIC
723 default "htcp" if DEFAULT_HTCP
724 default "hybla" if DEFAULT_HYBLA
725 default "vegas" if DEFAULT_VEGAS
726 default "westwood" if DEFAULT_WESTWOOD
727 default "veno" if DEFAULT_VENO
728 default "reno" if DEFAULT_RENO
729 default "dctcp" if DEFAULT_DCTCP
730 default "cdg" if DEFAULT_CDG
731 default "bbr" if DEFAULT_BBR
735 bool "TCP: MD5 Signature Option support (RFC2385)"
739 RFC2385 specifies a method of giving MD5 protection to TCP sessions.
740 Its main (only?) use is to protect BGP sessions between core routers