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"
301 depends on IPV6 || IPV6=n
304 depends on INET_XFRM_MODE_TUNNEL
306 Tunneling means encapsulating data of one protocol type within
307 another protocol and sending it over a channel that understands the
308 encapsulating protocol. This can be used with xfrm mode tunnel to give
309 the notion of a secure tunnel for IPSEC and then use routing protocol
312 config NET_UDP_TUNNEL
318 tristate "IP: Foo (IP protocols) over UDP"
320 select NET_UDP_TUNNEL
322 Foo over UDP allows any IP protocol to be directly encapsulated
323 over UDP include tunnels (IPIP, GRE, SIT). By encapsulating in UDP
324 network mechanisms and optimizations for UDP (such as ECMP
325 and RSS) can be leveraged to provide better service.
327 config NET_FOU_IP_TUNNELS
328 bool "IP: FOU encapsulation of IP tunnels"
329 depends on NET_IPIP || NET_IPGRE || IPV6_SIT
332 Allow configuration of FOU or GUE encapsulation for IP tunnels.
333 When this option is enabled IP tunnels can be configured to use
334 FOU or GUE encapsulation.
337 tristate "IP: AH transformation"
344 Support for IPsec AH.
349 tristate "IP: ESP transformation"
352 select CRYPTO_AUTHENC
358 select CRYPTO_ECHAINIV
360 Support for IPsec ESP.
365 tristate "IP: IPComp transformation"
366 select INET_XFRM_TUNNEL
369 Support for IP Payload Compression Protocol (IPComp) (RFC3173),
370 typically needed for IPsec.
374 config INET_XFRM_TUNNEL
383 config INET_XFRM_MODE_TRANSPORT
384 tristate "IP: IPsec transport mode"
388 Support for IPsec transport mode.
392 config INET_XFRM_MODE_TUNNEL
393 tristate "IP: IPsec tunnel mode"
397 Support for IPsec tunnel mode.
401 config INET_XFRM_MODE_BEET
402 tristate "IP: IPsec BEET mode"
406 Support for IPsec BEET mode.
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 config INET_DIAG_DESTROY
435 bool "INET: allow privileged process to administratively close sockets"
439 Provides a SOCK_DESTROY operation that allows privileged processes
440 (e.g., a connection manager or a network administration tool such as
441 ss) to close sockets opened by other processes. Closing a socket in
442 this way interrupts any blocking read/write/connect operations on
443 the socket and causes future socket calls to behave as if the socket
444 had been disconnected.
447 menuconfig TCP_CONG_ADVANCED
448 bool "TCP: advanced congestion control"
450 Support for selection of various TCP congestion control
453 Nearly all users can safely say no here, and a safe default
454 selection will be made (CUBIC with new Reno as a fallback).
461 tristate "Binary Increase Congestion (BIC) control"
464 BIC-TCP is a sender-side only change that ensures a linear RTT
465 fairness under large windows while offering both scalability and
466 bounded TCP-friendliness. The protocol combines two schemes
467 called additive increase and binary search increase. When the
468 congestion window is large, additive increase with a large
469 increment ensures linear RTT fairness as well as good
470 scalability. Under small congestion windows, binary search
471 increase provides TCP friendliness.
472 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
474 config TCP_CONG_CUBIC
478 This is version 2.0 of BIC-TCP which uses a cubic growth function
479 among other techniques.
480 See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
482 config TCP_CONG_WESTWOOD
483 tristate "TCP Westwood+"
486 TCP Westwood+ is a sender-side only modification of the TCP Reno
487 protocol stack that optimizes the performance of TCP congestion
488 control. It is based on end-to-end bandwidth estimation to set
489 congestion window and slow start threshold after a congestion
490 episode. Using this estimation, TCP Westwood+ adaptively sets a
491 slow start threshold and a congestion window which takes into
492 account the bandwidth used at the time congestion is experienced.
493 TCP Westwood+ significantly increases fairness wrt TCP Reno in
494 wired networks and throughput over wireless links.
500 H-TCP is a send-side only modifications of the TCP Reno
501 protocol stack that optimizes the performance of TCP
502 congestion control for high speed network links. It uses a
503 modeswitch to change the alpha and beta parameters of TCP Reno
504 based on network conditions and in a way so as to be fair with
505 other Reno and H-TCP flows.
507 config TCP_CONG_HSTCP
508 tristate "High Speed TCP"
511 Sally Floyd's High Speed TCP (RFC 3649) congestion control.
512 A modification to TCP's congestion control mechanism for use
513 with large congestion windows. A table indicates how much to
514 increase the congestion window by when an ACK is received.
515 For more detail see http://www.icir.org/floyd/hstcp.html
517 config TCP_CONG_HYBLA
518 tristate "TCP-Hybla congestion control algorithm"
521 TCP-Hybla is a sender-side only change that eliminates penalization of
522 long-RTT, large-bandwidth connections, like when satellite legs are
523 involved, especially when sharing a common bottleneck with normal
524 terrestrial connections.
526 config TCP_CONG_VEGAS
530 TCP Vegas is a sender-side only change to TCP that anticipates
531 the onset of congestion by estimating the bandwidth. TCP Vegas
532 adjusts the sending rate by modifying the congestion
533 window. TCP Vegas should provide less packet loss, but it is
534 not as aggressive as TCP Reno.
540 TCP NV is a follow up to TCP Vegas. It has been modified to deal with
541 10G networks, measurement noise introduced by LRO, GRO and interrupt
542 coalescence. In addition, it will decrease its cwnd multiplicatively
545 Note that in general congestion avoidance (cwnd decreased when # packets
546 queued grows) cannot coexist with congestion control (cwnd decreased only
547 when there is packet loss) due to fairness issues. One scenario when they
548 can coexist safely is when the CA flows have RTTs << CC flows RTTs.
550 For further details see http://www.brakmo.org/networking/tcp-nv/
552 config TCP_CONG_SCALABLE
553 tristate "Scalable TCP"
556 Scalable TCP is a sender-side only change to TCP which uses a
557 MIMD congestion control algorithm which has some nice scaling
558 properties, though is known to have fairness issues.
559 See http://www.deneholme.net/tom/scalable/
562 tristate "TCP Low Priority"
565 TCP Low Priority (TCP-LP), a distributed algorithm whose goal is
566 to utilize only the excess network bandwidth as compared to the
567 ``fair share`` of bandwidth as targeted by TCP.
568 See http://www-ece.rice.edu/networks/TCP-LP/
574 TCP Veno is a sender-side only enhancement of TCP to obtain better
575 throughput over wireless networks. TCP Veno makes use of state
576 distinguishing to circumvent the difficult judgment of the packet loss
577 type. TCP Veno cuts down less congestion window in response to random
579 See <http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1177186>
583 select TCP_CONG_VEGAS
586 YeAH-TCP is a sender-side high-speed enabled TCP congestion control
587 algorithm, which uses a mixed loss/delay approach to compute the
588 congestion window. It's design goals target high efficiency,
589 internal, RTT and Reno fairness, resilience to link loss while
590 keeping network elements load as low as possible.
592 For further details look here:
593 http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
595 config TCP_CONG_ILLINOIS
596 tristate "TCP Illinois"
599 TCP-Illinois is a sender-side modification of TCP Reno for
600 high speed long delay links. It uses round-trip-time to
601 adjust the alpha and beta parameters to achieve a higher average
602 throughput and maintain fairness.
604 For further details see:
605 http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
607 config TCP_CONG_DCTCP
608 tristate "DataCenter TCP (DCTCP)"
611 DCTCP leverages Explicit Congestion Notification (ECN) in the network to
612 provide multi-bit feedback to the end hosts. It is designed to provide:
614 - High burst tolerance (incast due to partition/aggregate),
615 - Low latency (short flows, queries),
616 - High throughput (continuous data updates, large file transfers) with
617 commodity, shallow-buffered switches.
619 All switches in the data center network running DCTCP must support
620 ECN marking and be configured for marking when reaching defined switch
621 buffer thresholds. The default ECN marking threshold heuristic for
622 DCTCP on switches is 20 packets (30KB) at 1Gbps, and 65 packets
623 (~100KB) at 10Gbps, but might need further careful tweaking.
625 For further details see:
626 http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
629 tristate "CAIA Delay-Gradient (CDG)"
632 CAIA Delay-Gradient (CDG) is a TCP congestion control that modifies
633 the TCP sender in order to:
635 o Use the delay gradient as a congestion signal.
636 o Back off with an average probability that is independent of the RTT.
637 o Coexist with flows that use loss-based congestion control.
638 o Tolerate packet loss unrelated to congestion.
640 For further details see:
641 D.A. Hayes and G. Armitage. "Revisiting TCP congestion control using
642 delay gradients." In Networking 2011. Preprint: http://goo.gl/No3vdg
649 BBR (Bottleneck Bandwidth and RTT) TCP congestion control aims to
650 maximize network utilization and minimize queues. It builds an explicit
651 model of the the bottleneck delivery rate and path round-trip
652 propagation delay. It tolerates packet loss and delay unrelated to
653 congestion. It can operate over LAN, WAN, cellular, wifi, or cable
654 modem links. It can coexist with flows that use loss-based congestion
655 control, and can operate with shallow buffers, deep buffers,
656 bufferbloat, policers, or AQM schemes that do not provide a delay
657 signal. It requires the fq ("Fair Queue") pacing packet scheduler.
660 prompt "Default TCP congestion control"
661 default DEFAULT_CUBIC
663 Select the TCP congestion control that will be used by default
667 bool "Bic" if TCP_CONG_BIC=y
670 bool "Cubic" if TCP_CONG_CUBIC=y
673 bool "Htcp" if TCP_CONG_HTCP=y
676 bool "Hybla" if TCP_CONG_HYBLA=y
679 bool "Vegas" if TCP_CONG_VEGAS=y
682 bool "Veno" if TCP_CONG_VENO=y
684 config DEFAULT_WESTWOOD
685 bool "Westwood" if TCP_CONG_WESTWOOD=y
688 bool "DCTCP" if TCP_CONG_DCTCP=y
691 bool "CDG" if TCP_CONG_CDG=y
694 bool "BBR" if TCP_CONG_BBR=y
702 config TCP_CONG_CUBIC
704 depends on !TCP_CONG_ADVANCED
707 config DEFAULT_TCP_CONG
709 default "bic" if DEFAULT_BIC
710 default "cubic" if DEFAULT_CUBIC
711 default "htcp" if DEFAULT_HTCP
712 default "hybla" if DEFAULT_HYBLA
713 default "vegas" if DEFAULT_VEGAS
714 default "westwood" if DEFAULT_WESTWOOD
715 default "veno" if DEFAULT_VENO
716 default "reno" if DEFAULT_RENO
717 default "dctcp" if DEFAULT_DCTCP
718 default "cdg" if DEFAULT_CDG
719 default "bbr" if DEFAULT_BBR
723 bool "TCP: MD5 Signature Option support (RFC2385)"
727 RFC2385 specifies a method of giving MD5 protection to TCP sessions.
728 Its main (only?) use is to protect BGP sessions between core routers