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 are interested in this, please see the preliminary
74 documentation at <http://www.compendium.com.ar/policy-routing.txt>
75 and <ftp://post.tepkom.ru/pub/vol2/Linux/docs/advanced-routing.tex>.
76 You will need supporting software from
77 <ftp://ftp.tux.org/pub/net/ip-routing/>.
81 config IP_ROUTE_MULTIPATH
82 bool "IP: equal cost multipath"
83 depends on IP_ADVANCED_ROUTER
85 Normally, the routing tables specify a single action to be taken in
86 a deterministic manner for a given packet. If you say Y here
87 however, it becomes possible to attach several actions to a packet
88 pattern, in effect specifying several alternative paths to travel
89 for those packets. The router considers all these paths to be of
90 equal "cost" and chooses one of them in a non-deterministic fashion
91 if a matching packet arrives.
93 config IP_ROUTE_VERBOSE
94 bool "IP: verbose route monitoring"
95 depends on IP_ADVANCED_ROUTER
97 If you say Y here, which is recommended, then the kernel will print
98 verbose messages regarding the routing, for example warnings about
99 received packets which look strange and could be evidence of an
100 attack or a misconfigured system somewhere. The information is
101 handled by the klogd daemon which is responsible for kernel messages
104 config IP_ROUTE_CLASSID
108 bool "IP: kernel level autoconfiguration"
110 This enables automatic configuration of IP addresses of devices and
111 of the routing table during kernel boot, based on either information
112 supplied on the kernel command line or by BOOTP or RARP protocols.
113 You need to say Y only for diskless machines requiring network
114 access to boot (in which case you want to say Y to "Root file system
115 on NFS" as well), because all other machines configure the network
116 in their startup scripts.
119 bool "IP: DHCP support"
122 If you want your Linux box to mount its whole root file system (the
123 one containing the directory /) from some other computer over the
124 net via NFS and you want the IP address of your computer to be
125 discovered automatically at boot time using the DHCP protocol (a
126 special protocol designed for doing this job), say Y here. In case
127 the boot ROM of your network card was designed for booting Linux and
128 does DHCP itself, providing all necessary information on the kernel
129 command line, you can say N here.
131 If unsure, say Y. Note that if you want to use DHCP, a DHCP server
132 must be operating on your network. Read
133 <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
136 bool "IP: BOOTP support"
139 If you want your Linux box to mount its whole root file system (the
140 one containing the directory /) from some other computer over the
141 net via NFS and you want the IP address of your computer to be
142 discovered automatically at boot time using the BOOTP protocol (a
143 special protocol designed for doing this job), say Y here. In case
144 the boot ROM of your network card was designed for booting Linux and
145 does BOOTP itself, providing all necessary information on the kernel
146 command line, you can say N here. If unsure, say Y. Note that if you
147 want to use BOOTP, a BOOTP server must be operating on your network.
148 Read <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
151 bool "IP: RARP support"
154 If you want your Linux box to mount its whole root file system (the
155 one containing the directory /) from some other computer over the
156 net via NFS and you want the IP address of your computer to be
157 discovered automatically at boot time using the RARP protocol (an
158 older protocol which is being obsoleted by BOOTP and DHCP), say Y
159 here. Note that if you want to use RARP, a RARP server must be
160 operating on your network. Read
161 <file:Documentation/filesystems/nfs/nfsroot.txt> for details.
164 tristate "IP: tunneling"
168 Tunneling means encapsulating data of one protocol type within
169 another protocol and sending it over a channel that understands the
170 encapsulating protocol. This particular tunneling driver implements
171 encapsulation of IP within IP, which sounds kind of pointless, but
172 can be useful if you want to make your (or some other) machine
173 appear on a different network than it physically is, or to use
174 mobile-IP facilities (allowing laptops to seamlessly move between
175 networks without changing their IP addresses).
177 Saying Y to this option will produce two modules ( = code which can
178 be inserted in and removed from the running kernel whenever you
179 want). Most people won't need this and can say N.
181 config NET_IPGRE_DEMUX
182 tristate "IP: GRE demultiplexer"
184 This is helper module to demultiplex GRE packets on GRE version field criteria.
185 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.
217 bool "IP: multicast routing"
218 depends on IP_MULTICAST
220 This is used if you want your machine to act as a router for IP
221 packets that have several destination addresses. It is needed on the
222 MBONE, a high bandwidth network on top of the Internet which carries
223 audio and video broadcasts. In order to do that, you would most
224 likely run the program mrouted. If you haven't heard about it, you
227 config IP_MROUTE_MULTIPLE_TABLES
228 bool "IP: multicast policy routing"
229 depends on IP_MROUTE && IP_ADVANCED_ROUTER
232 Normally, a multicast router runs a userspace daemon and decides
233 what to do with a multicast packet based on the source and
234 destination addresses. If you say Y here, the multicast router
235 will also be able to take interfaces and packet marks into
236 account and run multiple instances of userspace daemons
237 simultaneously, each one handling a single table.
242 bool "IP: PIM-SM version 1 support"
245 Kernel side support for Sparse Mode PIM (Protocol Independent
246 Multicast) version 1. This multicast routing protocol is used widely
247 because Cisco supports it. You need special software to use it
248 (pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
249 information about PIM.
251 Say Y if you want to use PIM-SM v1. Note that you can say N here if
252 you just want to use Dense Mode PIM.
255 bool "IP: PIM-SM version 2 support"
258 Kernel side support for Sparse Mode PIM version 2. In order to use
259 this, you need an experimental routing daemon supporting it (pimd or
260 gated-5). This routing protocol is not used widely, so say N unless
261 you want to play with it.
264 bool "IP: TCP syncookie support"
266 Normal TCP/IP networking is open to an attack known as "SYN
267 flooding". This denial-of-service attack prevents legitimate remote
268 users from being able to connect to your computer during an ongoing
269 attack and requires very little work from the attacker, who can
270 operate from anywhere on the Internet.
272 SYN cookies provide protection against this type of attack. If you
273 say Y here, the TCP/IP stack will use a cryptographic challenge
274 protocol known as "SYN cookies" to enable legitimate users to
275 continue to connect, even when your machine is under attack. There
276 is no need for the legitimate users to change their TCP/IP software;
277 SYN cookies work transparently to them. For technical information
278 about SYN cookies, check out <http://cr.yp.to/syncookies.html>.
280 If you are SYN flooded, the source address reported by the kernel is
281 likely to have been forged by the attacker; it is only reported as
282 an aid in tracing the packets to their actual source and should not
283 be taken as absolute truth.
285 SYN cookies may prevent correct error reporting on clients when the
286 server is really overloaded. If this happens frequently better turn
289 If you say Y here, you can disable SYN cookies at run time by
290 saying Y to "/proc file system support" and
291 "Sysctl support" below and executing the command
293 echo 0 > /proc/sys/net/ipv4/tcp_syncookies
295 after the /proc file system has been mounted.
300 tristate "Virtual (secure) IP: tunneling"
303 depends on INET_XFRM_MODE_TUNNEL
305 Tunneling means encapsulating data of one protocol type within
306 another protocol and sending it over a channel that understands the
307 encapsulating protocol. This can be used with xfrm mode tunnel to give
308 the notion of a secure tunnel for IPSEC and then use routing protocol
311 config NET_UDP_TUNNEL
317 tristate "IP: Foo (IP protocols) over UDP"
319 select NET_UDP_TUNNEL
321 Foo over UDP allows any IP protocol to be directly encapsulated
322 over UDP include tunnels (IPIP, GRE, SIT). By encapsulating in UDP
323 network mechanisms and optimizations for UDP (such as ECMP
324 and RSS) can be leveraged to provide better service.
326 config NET_FOU_IP_TUNNELS
327 bool "IP: FOU encapsulation of IP tunnels"
328 depends on NET_IPIP || NET_IPGRE || IPV6_SIT
331 Allow configuration of FOU or GUE encapsulation for IP tunnels.
332 When this option is enabled IP tunnels can be configured to use
333 FOU or GUE encapsulation.
336 tristate "IP: AH transformation"
343 Support for IPsec AH.
348 tristate "IP: ESP transformation"
351 select CRYPTO_AUTHENC
357 select CRYPTO_ECHAINIV
359 Support for IPsec ESP.
364 tristate "IP: IPComp transformation"
365 select INET_XFRM_TUNNEL
368 Support for IP Payload Compression Protocol (IPComp) (RFC3173),
369 typically needed for IPsec.
373 config INET_XFRM_TUNNEL
382 config INET_XFRM_MODE_TRANSPORT
383 tristate "IP: IPsec transport mode"
387 Support for IPsec transport mode.
391 config INET_XFRM_MODE_TUNNEL
392 tristate "IP: IPsec tunnel mode"
396 Support for IPsec tunnel mode.
400 config INET_XFRM_MODE_BEET
401 tristate "IP: IPsec BEET mode"
405 Support for IPsec BEET mode.
410 tristate "INET: socket monitoring interface"
413 Support for INET (TCP, DCCP, etc) socket monitoring interface used by
414 native Linux tools such as ss. ss is included in iproute2, currently
417 http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2
423 def_tristate INET_DIAG
426 tristate "UDP: socket monitoring interface"
427 depends on INET_DIAG && (IPV6 || IPV6=n)
430 Support for UDP socket monitoring interface used by the ss tool.
434 tristate "RAW: socket monitoring interface"
435 depends on INET_DIAG && (IPV6 || IPV6=n)
438 Support for RAW socket monitoring interface used by the ss tool.
441 config INET_DIAG_DESTROY
442 bool "INET: allow privileged process to administratively close sockets"
446 Provides a SOCK_DESTROY operation that allows privileged processes
447 (e.g., a connection manager or a network administration tool such as
448 ss) to close sockets opened by other processes. Closing a socket in
449 this way interrupts any blocking read/write/connect operations on
450 the socket and causes future socket calls to behave as if the socket
451 had been disconnected.
454 menuconfig TCP_CONG_ADVANCED
455 bool "TCP: advanced congestion control"
457 Support for selection of various TCP congestion control
460 Nearly all users can safely say no here, and a safe default
461 selection will be made (CUBIC with new Reno as a fallback).
468 tristate "Binary Increase Congestion (BIC) control"
471 BIC-TCP is a sender-side only change that ensures a linear RTT
472 fairness under large windows while offering both scalability and
473 bounded TCP-friendliness. The protocol combines two schemes
474 called additive increase and binary search increase. When the
475 congestion window is large, additive increase with a large
476 increment ensures linear RTT fairness as well as good
477 scalability. Under small congestion windows, binary search
478 increase provides TCP friendliness.
479 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
481 config TCP_CONG_CUBIC
485 This is version 2.0 of BIC-TCP which uses a cubic growth function
486 among other techniques.
487 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
489 config TCP_CONG_WESTWOOD
490 tristate "TCP Westwood+"
493 TCP Westwood+ is a sender-side only modification of the TCP Reno
494 protocol stack that optimizes the performance of TCP congestion
495 control. It is based on end-to-end bandwidth estimation to set
496 congestion window and slow start threshold after a congestion
497 episode. Using this estimation, TCP Westwood+ adaptively sets a
498 slow start threshold and a congestion window which takes into
499 account the bandwidth used at the time congestion is experienced.
500 TCP Westwood+ significantly increases fairness wrt TCP Reno in
501 wired networks and throughput over wireless links.
507 H-TCP is a send-side only modifications of the TCP Reno
508 protocol stack that optimizes the performance of TCP
509 congestion control for high speed network links. It uses a
510 modeswitch to change the alpha and beta parameters of TCP Reno
511 based on network conditions and in a way so as to be fair with
512 other Reno and H-TCP flows.
514 config TCP_CONG_HSTCP
515 tristate "High Speed TCP"
518 Sally Floyd's High Speed TCP (RFC 3649) congestion control.
519 A modification to TCP's congestion control mechanism for use
520 with large congestion windows. A table indicates how much to
521 increase the congestion window by when an ACK is received.
522 For more detail see http://www.icir.org/floyd/hstcp.html
524 config TCP_CONG_HYBLA
525 tristate "TCP-Hybla congestion control algorithm"
528 TCP-Hybla is a sender-side only change that eliminates penalization of
529 long-RTT, large-bandwidth connections, like when satellite legs are
530 involved, especially when sharing a common bottleneck with normal
531 terrestrial connections.
533 config TCP_CONG_VEGAS
537 TCP Vegas is a sender-side only change to TCP that anticipates
538 the onset of congestion by estimating the bandwidth. TCP Vegas
539 adjusts the sending rate by modifying the congestion
540 window. TCP Vegas should provide less packet loss, but it is
541 not as aggressive as TCP Reno.
547 TCP NV is a follow up to TCP Vegas. It has been modified to deal with
548 10G networks, measurement noise introduced by LRO, GRO and interrupt
549 coalescence. In addition, it will decrease its cwnd multiplicatively
552 Note that in general congestion avoidance (cwnd decreased when # packets
553 queued grows) cannot coexist with congestion control (cwnd decreased only
554 when there is packet loss) due to fairness issues. One scenario when they
555 can coexist safely is when the CA flows have RTTs << CC flows RTTs.
557 For further details see http://www.brakmo.org/networking/tcp-nv/
559 config TCP_CONG_SCALABLE
560 tristate "Scalable TCP"
563 Scalable TCP is a sender-side only change to TCP which uses a
564 MIMD congestion control algorithm which has some nice scaling
565 properties, though is known to have fairness issues.
566 See http://www.deneholme.net/tom/scalable/
569 tristate "TCP Low Priority"
572 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
573 to utilize only the excess network bandwidth as compared to the
574 ``fair share`` of bandwidth as targeted by TCP.
575 See http://www-ece.rice.edu/networks/TCP-LP/
581 TCP Veno is a sender-side only enhancement of TCP to obtain better
582 throughput over wireless networks. TCP Veno makes use of state
583 distinguishing to circumvent the difficult judgment of the packet loss
584 type. TCP Veno cuts down less congestion window in response to random
586 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
590 select TCP_CONG_VEGAS
593 YeAH-TCP is a sender-side high-speed enabled TCP congestion control
594 algorithm, which uses a mixed loss/delay approach to compute the
595 congestion window. It's design goals target high efficiency,
596 internal, RTT and Reno fairness, resilience to link loss while
597 keeping network elements load as low as possible.
599 For further details look here:
600 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
602 config TCP_CONG_ILLINOIS
603 tristate "TCP Illinois"
606 TCP-Illinois is a sender-side modification of TCP Reno for
607 high speed long delay links. It uses round-trip-time to
608 adjust the alpha and beta parameters to achieve a higher average
609 throughput and maintain fairness.
611 For further details see:
612 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
614 config TCP_CONG_DCTCP
615 tristate "DataCenter TCP (DCTCP)"
618 DCTCP leverages Explicit Congestion Notification (ECN) in the network to
619 provide multi-bit feedback to the end hosts. It is designed to provide:
621 - High burst tolerance (incast due to partition/aggregate),
622 - Low latency (short flows, queries),
623 - High throughput (continuous data updates, large file transfers) with
624 commodity, shallow-buffered switches.
626 All switches in the data center network running DCTCP must support
627 ECN marking and be configured for marking when reaching defined switch
628 buffer thresholds. The default ECN marking threshold heuristic for
629 DCTCP on switches is 20 packets (30KB) at 1Gbps, and 65 packets
630 (~100KB) at 10Gbps, but might need further careful tweaking.
632 For further details see:
633 http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
636 tristate "CAIA Delay-Gradient (CDG)"
639 CAIA Delay-Gradient (CDG) is a TCP congestion control that modifies
640 the TCP sender in order to:
642 o Use the delay gradient as a congestion signal.
643 o Back off with an average probability that is independent of the RTT.
644 o Coexist with flows that use loss-based congestion control.
645 o Tolerate packet loss unrelated to congestion.
647 For further details see:
648 D.A. Hayes and G. Armitage. "Revisiting TCP congestion control using
649 delay gradients." In Networking 2011. Preprint: http://goo.gl/No3vdg
656 BBR (Bottleneck Bandwidth and RTT) TCP congestion control aims to
657 maximize network utilization and minimize queues. It builds an explicit
658 model of the the bottleneck delivery rate and path round-trip
659 propagation delay. It tolerates packet loss and delay unrelated to
660 congestion. It can operate over LAN, WAN, cellular, wifi, or cable
661 modem links. It can coexist with flows that use loss-based congestion
662 control, and can operate with shallow buffers, deep buffers,
663 bufferbloat, policers, or AQM schemes that do not provide a delay
664 signal. It requires the fq ("Fair Queue") pacing packet scheduler.
667 prompt "Default TCP congestion control"
668 default DEFAULT_CUBIC
670 Select the TCP congestion control that will be used by default
674 bool "Bic" if TCP_CONG_BIC=y
677 bool "Cubic" if TCP_CONG_CUBIC=y
680 bool "Htcp" if TCP_CONG_HTCP=y
683 bool "Hybla" if TCP_CONG_HYBLA=y
686 bool "Vegas" if TCP_CONG_VEGAS=y
689 bool "Veno" if TCP_CONG_VENO=y
691 config DEFAULT_WESTWOOD
692 bool "Westwood" if TCP_CONG_WESTWOOD=y
695 bool "DCTCP" if TCP_CONG_DCTCP=y
698 bool "CDG" if TCP_CONG_CDG=y
701 bool "BBR" if TCP_CONG_BBR=y
709 config TCP_CONG_CUBIC
711 depends on !TCP_CONG_ADVANCED
714 config DEFAULT_TCP_CONG
716 default "bic" if DEFAULT_BIC
717 default "cubic" if DEFAULT_CUBIC
718 default "htcp" if DEFAULT_HTCP
719 default "hybla" if DEFAULT_HYBLA
720 default "vegas" if DEFAULT_VEGAS
721 default "westwood" if DEFAULT_WESTWOOD
722 default "veno" if DEFAULT_VENO
723 default "reno" if DEFAULT_RENO
724 default "dctcp" if DEFAULT_DCTCP
725 default "cdg" if DEFAULT_CDG
726 default "bbr" if DEFAULT_BBR
730 bool "TCP: MD5 Signature Option support (RFC2385)"
734 RFC2385 specifies a method of giving MD5 protection to TCP sessions.
735 Its main (only?) use is to protect BGP sessions between core routers