11da177e4SLinus Torvalds# 21da177e4SLinus Torvalds# IP configuration 31da177e4SLinus Torvalds# 41da177e4SLinus Torvaldsconfig IP_MULTICAST 51da177e4SLinus Torvalds bool "IP: multicasting" 61da177e4SLinus Torvalds help 71da177e4SLinus Torvalds This is code for addressing several networked computers at once, 81da177e4SLinus Torvalds enlarging your kernel by about 2 KB. You need multicasting if you 91da177e4SLinus Torvalds intend to participate in the MBONE, a high bandwidth network on top 101da177e4SLinus Torvalds of the Internet which carries audio and video broadcasts. More 111da177e4SLinus Torvalds information about the MBONE is on the WWW at 12936bb14cSAdrian Bunk <http://www.savetz.com/mbone/>. Information about the multicast 131da177e4SLinus Torvalds capabilities of the various network cards is contained in 141da177e4SLinus Torvalds <file:Documentation/networking/multicast.txt>. For most people, it's 151da177e4SLinus Torvalds safe to say N. 161da177e4SLinus Torvalds 171da177e4SLinus Torvaldsconfig IP_ADVANCED_ROUTER 181da177e4SLinus Torvalds bool "IP: advanced router" 191da177e4SLinus Torvalds ---help--- 201da177e4SLinus Torvalds If you intend to run your Linux box mostly as a router, i.e. as a 211da177e4SLinus Torvalds computer that forwards and redistributes network packets, say Y; you 221da177e4SLinus Torvalds will then be presented with several options that allow more precise 231da177e4SLinus Torvalds control about the routing process. 241da177e4SLinus Torvalds 251da177e4SLinus Torvalds The answer to this question won't directly affect the kernel: 261da177e4SLinus Torvalds answering N will just cause the configurator to skip all the 271da177e4SLinus Torvalds questions about advanced routing. 281da177e4SLinus Torvalds 291da177e4SLinus Torvalds Note that your box can only act as a router if you enable IP 301da177e4SLinus Torvalds forwarding in your kernel; you can do that by saying Y to "/proc 311da177e4SLinus Torvalds file system support" and "Sysctl support" below and executing the 321da177e4SLinus Torvalds line 331da177e4SLinus Torvalds 341da177e4SLinus Torvalds echo "1" > /proc/sys/net/ipv4/ip_forward 351da177e4SLinus Torvalds 361da177e4SLinus Torvalds at boot time after the /proc file system has been mounted. 371da177e4SLinus Torvalds 381da177e4SLinus Torvalds If you turn on IP forwarding, you will also get the rp_filter, which 391da177e4SLinus Torvalds automatically rejects incoming packets if the routing table entry 401da177e4SLinus Torvalds for their source address doesn't match the network interface they're 411da177e4SLinus Torvalds arriving on. This has security advantages because it prevents the 421da177e4SLinus Torvalds so-called IP spoofing, however it can pose problems if you use 431da177e4SLinus Torvalds asymmetric routing (packets from you to a host take a different path 441da177e4SLinus Torvalds than packets from that host to you) or if you operate a non-routing 451da177e4SLinus Torvalds host which has several IP addresses on different interfaces. To turn 461da177e4SLinus Torvalds rp_filter off use: 471da177e4SLinus Torvalds 481da177e4SLinus Torvalds echo 0 > /proc/sys/net/ipv4/conf/<device>/rp_filter 491da177e4SLinus Torvalds or 501da177e4SLinus Torvalds echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter 511da177e4SLinus Torvalds 521da177e4SLinus Torvalds If unsure, say N here. 531da177e4SLinus Torvalds 54bb298ca3SDavid S. Millerchoice 55bb298ca3SDavid S. Miller prompt "Choose IP: FIB lookup algorithm (choose FIB_HASH if unsure)" 56bb298ca3SDavid S. Miller depends on IP_ADVANCED_ROUTER 576876f95fSAdrian Bunk default ASK_IP_FIB_HASH 58bb298ca3SDavid S. Miller 596876f95fSAdrian Bunkconfig ASK_IP_FIB_HASH 60bb298ca3SDavid S. Miller bool "FIB_HASH" 61bb298ca3SDavid S. Miller ---help--- 62bb298ca3SDavid S. Miller Current FIB is very proven and good enough for most users. 63bb298ca3SDavid S. Miller 64bb298ca3SDavid S. Millerconfig IP_FIB_TRIE 65bb298ca3SDavid S. Miller bool "FIB_TRIE" 66bb298ca3SDavid S. Miller ---help--- 6744c09201SMatt LaPlante Use new experimental LC-trie as FIB lookup algorithm. 68bb298ca3SDavid S. Miller This improves lookup performance if you have a large 69bb298ca3SDavid S. Miller number of routes. 70bb298ca3SDavid S. Miller 71bb298ca3SDavid S. Miller LC-trie is a longest matching prefix lookup algorithm which 72bb298ca3SDavid S. Miller performs better than FIB_HASH for large routing tables. 73bb298ca3SDavid S. Miller But, it consumes more memory and is more complex. 74bb298ca3SDavid S. Miller 75bb298ca3SDavid S. Miller LC-trie is described in: 76bb298ca3SDavid S. Miller 77bb298ca3SDavid S. Miller IP-address lookup using LC-tries. Stefan Nilsson and Gunnar Karlsson 78bb298ca3SDavid S. Miller IEEE Journal on Selected Areas in Communications, 17(6):1083-1092, June 1999 79bb298ca3SDavid S. Miller An experimental study of compression methods for dynamic tries 80bb298ca3SDavid S. Miller Stefan Nilsson and Matti Tikkanen. Algorithmica, 33(1):19-33, 2002. 81bb298ca3SDavid S. Miller http://www.nada.kth.se/~snilsson/public/papers/dyntrie2/ 82bb298ca3SDavid S. Miller 83bb298ca3SDavid S. Millerendchoice 84bb298ca3SDavid S. Miller 85bb298ca3SDavid S. Millerconfig IP_FIB_HASH 866876f95fSAdrian Bunk def_bool ASK_IP_FIB_HASH || !IP_ADVANCED_ROUTER 87bb298ca3SDavid S. Miller 881da177e4SLinus Torvaldsconfig IP_MULTIPLE_TABLES 891da177e4SLinus Torvalds bool "IP: policy routing" 901da177e4SLinus Torvalds depends on IP_ADVANCED_ROUTER 91e1ef4bf2SThomas Graf select FIB_RULES 921da177e4SLinus Torvalds ---help--- 931da177e4SLinus Torvalds Normally, a router decides what to do with a received packet based 941da177e4SLinus Torvalds solely on the packet's final destination address. If you say Y here, 951da177e4SLinus Torvalds the Linux router will also be able to take the packet's source 961da177e4SLinus Torvalds address into account. Furthermore, the TOS (Type-Of-Service) field 971da177e4SLinus Torvalds of the packet can be used for routing decisions as well. 981da177e4SLinus Torvalds 991da177e4SLinus Torvalds If you are interested in this, please see the preliminary 1001da177e4SLinus Torvalds documentation at <http://www.compendium.com.ar/policy-routing.txt> 1011da177e4SLinus Torvalds and <ftp://post.tepkom.ru/pub/vol2/Linux/docs/advanced-routing.tex>. 1021da177e4SLinus Torvalds You will need supporting software from 1031da177e4SLinus Torvalds <ftp://ftp.tux.org/pub/net/ip-routing/>. 1041da177e4SLinus Torvalds 1051da177e4SLinus Torvalds If unsure, say N. 1061da177e4SLinus Torvalds 1071da177e4SLinus Torvaldsconfig IP_ROUTE_MULTIPATH 1081da177e4SLinus Torvalds bool "IP: equal cost multipath" 1091da177e4SLinus Torvalds depends on IP_ADVANCED_ROUTER 1101da177e4SLinus Torvalds help 1111da177e4SLinus Torvalds Normally, the routing tables specify a single action to be taken in 1121da177e4SLinus Torvalds a deterministic manner for a given packet. If you say Y here 1131da177e4SLinus Torvalds however, it becomes possible to attach several actions to a packet 1141da177e4SLinus Torvalds pattern, in effect specifying several alternative paths to travel 1151da177e4SLinus Torvalds for those packets. The router considers all these paths to be of 1161da177e4SLinus Torvalds equal "cost" and chooses one of them in a non-deterministic fashion 1171da177e4SLinus Torvalds if a matching packet arrives. 1181da177e4SLinus Torvalds 1191da177e4SLinus Torvaldsconfig IP_ROUTE_MULTIPATH_CACHED 1201da177e4SLinus Torvalds bool "IP: equal cost multipath with caching support (EXPERIMENTAL)" 121eaa1c5d0SHans-Juergen Tappe (SYSGO AG) depends on IP_ROUTE_MULTIPATH 1221da177e4SLinus Torvalds help 1231da177e4SLinus Torvalds Normally, equal cost multipath routing is not supported by the 1241da177e4SLinus Torvalds routing cache. If you say Y here, alternative routes are cached 1251da177e4SLinus Torvalds and on cache lookup a route is chosen in a configurable fashion. 1261da177e4SLinus Torvalds 1271da177e4SLinus Torvalds If unsure, say N. 1281da177e4SLinus Torvalds 1291da177e4SLinus Torvaldsconfig IP_ROUTE_MULTIPATH_RR 1301da177e4SLinus Torvalds tristate "MULTIPATH: round robin algorithm" 1311da177e4SLinus Torvalds depends on IP_ROUTE_MULTIPATH_CACHED 1321da177e4SLinus Torvalds help 1331da177e4SLinus Torvalds Mulitpath routes are chosen according to Round Robin 1341da177e4SLinus Torvalds 1351da177e4SLinus Torvaldsconfig IP_ROUTE_MULTIPATH_RANDOM 1361da177e4SLinus Torvalds tristate "MULTIPATH: random algorithm" 1371da177e4SLinus Torvalds depends on IP_ROUTE_MULTIPATH_CACHED 1381da177e4SLinus Torvalds help 1391da177e4SLinus Torvalds Multipath routes are chosen in a random fashion. Actually, 1401da177e4SLinus Torvalds there is no weight for a route. The advantage of this policy 1411da177e4SLinus Torvalds is that it is implemented stateless and therefore introduces only 1421da177e4SLinus Torvalds a very small delay. 1431da177e4SLinus Torvalds 1441da177e4SLinus Torvaldsconfig IP_ROUTE_MULTIPATH_WRANDOM 1451da177e4SLinus Torvalds tristate "MULTIPATH: weighted random algorithm" 1461da177e4SLinus Torvalds depends on IP_ROUTE_MULTIPATH_CACHED 1471da177e4SLinus Torvalds help 1481da177e4SLinus Torvalds Multipath routes are chosen in a weighted random fashion. 1491da177e4SLinus Torvalds The per route weights are the weights visible via ip route 2. As the 1501da177e4SLinus Torvalds corresponding state management introduces some overhead routing delay 1511da177e4SLinus Torvalds is increased. 1521da177e4SLinus Torvalds 1531da177e4SLinus Torvaldsconfig IP_ROUTE_MULTIPATH_DRR 1541da177e4SLinus Torvalds tristate "MULTIPATH: interface round robin algorithm" 1551da177e4SLinus Torvalds depends on IP_ROUTE_MULTIPATH_CACHED 1561da177e4SLinus Torvalds help 1571da177e4SLinus Torvalds Connections are distributed in a round robin fashion over the 1581da177e4SLinus Torvalds available interfaces. This policy makes sense if the connections 1591da177e4SLinus Torvalds should be primarily distributed on interfaces and not on routes. 1601da177e4SLinus Torvalds 1611da177e4SLinus Torvaldsconfig IP_ROUTE_VERBOSE 1621da177e4SLinus Torvalds bool "IP: verbose route monitoring" 1631da177e4SLinus Torvalds depends on IP_ADVANCED_ROUTER 1641da177e4SLinus Torvalds help 1651da177e4SLinus Torvalds If you say Y here, which is recommended, then the kernel will print 1661da177e4SLinus Torvalds verbose messages regarding the routing, for example warnings about 1671da177e4SLinus Torvalds received packets which look strange and could be evidence of an 1681da177e4SLinus Torvalds attack or a misconfigured system somewhere. The information is 1691da177e4SLinus Torvalds handled by the klogd daemon which is responsible for kernel messages 1701da177e4SLinus Torvalds ("man klogd"). 1711da177e4SLinus Torvalds 1721da177e4SLinus Torvaldsconfig IP_PNP 1731da177e4SLinus Torvalds bool "IP: kernel level autoconfiguration" 1741da177e4SLinus Torvalds help 1751da177e4SLinus Torvalds This enables automatic configuration of IP addresses of devices and 1761da177e4SLinus Torvalds of the routing table during kernel boot, based on either information 1771da177e4SLinus Torvalds supplied on the kernel command line or by BOOTP or RARP protocols. 1781da177e4SLinus Torvalds You need to say Y only for diskless machines requiring network 1791da177e4SLinus Torvalds access to boot (in which case you want to say Y to "Root file system 1801da177e4SLinus Torvalds on NFS" as well), because all other machines configure the network 1811da177e4SLinus Torvalds in their startup scripts. 1821da177e4SLinus Torvalds 1831da177e4SLinus Torvaldsconfig IP_PNP_DHCP 1841da177e4SLinus Torvalds bool "IP: DHCP support" 1851da177e4SLinus Torvalds depends on IP_PNP 1861da177e4SLinus Torvalds ---help--- 1871da177e4SLinus Torvalds If you want your Linux box to mount its whole root file system (the 1881da177e4SLinus Torvalds one containing the directory /) from some other computer over the 1891da177e4SLinus Torvalds net via NFS and you want the IP address of your computer to be 1901da177e4SLinus Torvalds discovered automatically at boot time using the DHCP protocol (a 1911da177e4SLinus Torvalds special protocol designed for doing this job), say Y here. In case 1921da177e4SLinus Torvalds the boot ROM of your network card was designed for booting Linux and 1931da177e4SLinus Torvalds does DHCP itself, providing all necessary information on the kernel 1941da177e4SLinus Torvalds command line, you can say N here. 1951da177e4SLinus Torvalds 1961da177e4SLinus Torvalds If unsure, say Y. Note that if you want to use DHCP, a DHCP server 1971da177e4SLinus Torvalds must be operating on your network. Read 1981da177e4SLinus Torvalds <file:Documentation/nfsroot.txt> for details. 1991da177e4SLinus Torvalds 2001da177e4SLinus Torvaldsconfig IP_PNP_BOOTP 2011da177e4SLinus Torvalds bool "IP: BOOTP support" 2021da177e4SLinus Torvalds depends on IP_PNP 2031da177e4SLinus Torvalds ---help--- 2041da177e4SLinus Torvalds If you want your Linux box to mount its whole root file system (the 2051da177e4SLinus Torvalds one containing the directory /) from some other computer over the 2061da177e4SLinus Torvalds net via NFS and you want the IP address of your computer to be 2071da177e4SLinus Torvalds discovered automatically at boot time using the BOOTP protocol (a 2081da177e4SLinus Torvalds special protocol designed for doing this job), say Y here. In case 2091da177e4SLinus Torvalds the boot ROM of your network card was designed for booting Linux and 2101da177e4SLinus Torvalds does BOOTP itself, providing all necessary information on the kernel 2111da177e4SLinus Torvalds command line, you can say N here. If unsure, say Y. Note that if you 2121da177e4SLinus Torvalds want to use BOOTP, a BOOTP server must be operating on your network. 2131da177e4SLinus Torvalds Read <file:Documentation/nfsroot.txt> for details. 2141da177e4SLinus Torvalds 2151da177e4SLinus Torvaldsconfig IP_PNP_RARP 2161da177e4SLinus Torvalds bool "IP: RARP support" 2171da177e4SLinus Torvalds depends on IP_PNP 2181da177e4SLinus Torvalds help 2191da177e4SLinus Torvalds If you want your Linux box to mount its whole root file system (the 2201da177e4SLinus Torvalds one containing the directory /) from some other computer over the 2211da177e4SLinus Torvalds net via NFS and you want the IP address of your computer to be 2221da177e4SLinus Torvalds discovered automatically at boot time using the RARP protocol (an 2231da177e4SLinus Torvalds older protocol which is being obsoleted by BOOTP and DHCP), say Y 2241da177e4SLinus Torvalds here. Note that if you want to use RARP, a RARP server must be 2251da177e4SLinus Torvalds operating on your network. Read <file:Documentation/nfsroot.txt> for 2261da177e4SLinus Torvalds details. 2271da177e4SLinus Torvalds 2281da177e4SLinus Torvalds# not yet ready.. 2291da177e4SLinus Torvalds# bool ' IP: ARP support' CONFIG_IP_PNP_ARP 2301da177e4SLinus Torvaldsconfig NET_IPIP 2311da177e4SLinus Torvalds tristate "IP: tunneling" 232d2acc347SHerbert Xu select INET_TUNNEL 2331da177e4SLinus Torvalds ---help--- 2341da177e4SLinus Torvalds Tunneling means encapsulating data of one protocol type within 2351da177e4SLinus Torvalds another protocol and sending it over a channel that understands the 2361da177e4SLinus Torvalds encapsulating protocol. This particular tunneling driver implements 2371da177e4SLinus Torvalds encapsulation of IP within IP, which sounds kind of pointless, but 2381da177e4SLinus Torvalds can be useful if you want to make your (or some other) machine 2391da177e4SLinus Torvalds appear on a different network than it physically is, or to use 2401da177e4SLinus Torvalds mobile-IP facilities (allowing laptops to seamlessly move between 2411da177e4SLinus Torvalds networks without changing their IP addresses). 2421da177e4SLinus Torvalds 2431da177e4SLinus Torvalds Saying Y to this option will produce two modules ( = code which can 2441da177e4SLinus Torvalds be inserted in and removed from the running kernel whenever you 2451da177e4SLinus Torvalds want). Most people won't need this and can say N. 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvaldsconfig NET_IPGRE 2481da177e4SLinus Torvalds tristate "IP: GRE tunnels over IP" 2491da177e4SLinus Torvalds help 2501da177e4SLinus Torvalds Tunneling means encapsulating data of one protocol type within 2511da177e4SLinus Torvalds another protocol and sending it over a channel that understands the 2521da177e4SLinus Torvalds encapsulating protocol. This particular tunneling driver implements 2531da177e4SLinus Torvalds GRE (Generic Routing Encapsulation) and at this time allows 2541da177e4SLinus Torvalds encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure. 2551da177e4SLinus Torvalds This driver is useful if the other endpoint is a Cisco router: Cisco 2561da177e4SLinus Torvalds likes GRE much better than the other Linux tunneling driver ("IP 2571da177e4SLinus Torvalds tunneling" above). In addition, GRE allows multicast redistribution 2581da177e4SLinus Torvalds through the tunnel. 2591da177e4SLinus Torvalds 2601da177e4SLinus Torvaldsconfig NET_IPGRE_BROADCAST 2611da177e4SLinus Torvalds bool "IP: broadcast GRE over IP" 2621da177e4SLinus Torvalds depends on IP_MULTICAST && NET_IPGRE 2631da177e4SLinus Torvalds help 2641da177e4SLinus Torvalds One application of GRE/IP is to construct a broadcast WAN (Wide Area 2651da177e4SLinus Torvalds Network), which looks like a normal Ethernet LAN (Local Area 2661da177e4SLinus Torvalds Network), but can be distributed all over the Internet. If you want 2671da177e4SLinus Torvalds to do that, say Y here and to "IP multicast routing" below. 2681da177e4SLinus Torvalds 2691da177e4SLinus Torvaldsconfig IP_MROUTE 2701da177e4SLinus Torvalds bool "IP: multicast routing" 2711da177e4SLinus Torvalds depends on IP_MULTICAST 2721da177e4SLinus Torvalds help 2731da177e4SLinus Torvalds This is used if you want your machine to act as a router for IP 2741da177e4SLinus Torvalds packets that have several destination addresses. It is needed on the 2751da177e4SLinus Torvalds MBONE, a high bandwidth network on top of the Internet which carries 2761da177e4SLinus Torvalds audio and video broadcasts. In order to do that, you would most 2771da177e4SLinus Torvalds likely run the program mrouted. Information about the multicast 2781da177e4SLinus Torvalds capabilities of the various network cards is contained in 2791da177e4SLinus Torvalds <file:Documentation/networking/multicast.txt>. If you haven't heard 2801da177e4SLinus Torvalds about it, you don't need it. 2811da177e4SLinus Torvalds 2821da177e4SLinus Torvaldsconfig IP_PIMSM_V1 2831da177e4SLinus Torvalds bool "IP: PIM-SM version 1 support" 2841da177e4SLinus Torvalds depends on IP_MROUTE 2851da177e4SLinus Torvalds help 2861da177e4SLinus Torvalds Kernel side support for Sparse Mode PIM (Protocol Independent 2871da177e4SLinus Torvalds Multicast) version 1. This multicast routing protocol is used widely 2881da177e4SLinus Torvalds because Cisco supports it. You need special software to use it 2891da177e4SLinus Torvalds (pimd-v1). Please see <http://netweb.usc.edu/pim/> for more 2901da177e4SLinus Torvalds information about PIM. 2911da177e4SLinus Torvalds 2921da177e4SLinus Torvalds Say Y if you want to use PIM-SM v1. Note that you can say N here if 2931da177e4SLinus Torvalds you just want to use Dense Mode PIM. 2941da177e4SLinus Torvalds 2951da177e4SLinus Torvaldsconfig IP_PIMSM_V2 2961da177e4SLinus Torvalds bool "IP: PIM-SM version 2 support" 2971da177e4SLinus Torvalds depends on IP_MROUTE 2981da177e4SLinus Torvalds help 2991da177e4SLinus Torvalds Kernel side support for Sparse Mode PIM version 2. In order to use 3001da177e4SLinus Torvalds this, you need an experimental routing daemon supporting it (pimd or 3011da177e4SLinus Torvalds gated-5). This routing protocol is not used widely, so say N unless 3021da177e4SLinus Torvalds you want to play with it. 3031da177e4SLinus Torvalds 3041da177e4SLinus Torvaldsconfig ARPD 3051da177e4SLinus Torvalds bool "IP: ARP daemon support (EXPERIMENTAL)" 3066a2e9b73SSam Ravnborg depends on EXPERIMENTAL 3071da177e4SLinus Torvalds ---help--- 3081da177e4SLinus Torvalds Normally, the kernel maintains an internal cache which maps IP 3091da177e4SLinus Torvalds addresses to hardware addresses on the local network, so that 3101da177e4SLinus Torvalds Ethernet/Token Ring/ etc. frames are sent to the proper address on 3111da177e4SLinus Torvalds the physical networking layer. For small networks having a few 3121da177e4SLinus Torvalds hundred directly connected hosts or less, keeping this address 3131da177e4SLinus Torvalds resolution (ARP) cache inside the kernel works well. However, 3141da177e4SLinus Torvalds maintaining an internal ARP cache does not work well for very large 3151da177e4SLinus Torvalds switched networks, and will use a lot of kernel memory if TCP/IP 3161da177e4SLinus Torvalds connections are made to many machines on the network. 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds If you say Y here, the kernel's internal ARP cache will never grow 3191da177e4SLinus Torvalds to more than 256 entries (the oldest entries are expired in a LIFO 3201da177e4SLinus Torvalds manner) and communication will be attempted with the user space ARP 3211da177e4SLinus Torvalds daemon arpd. Arpd then answers the address resolution request either 3221da177e4SLinus Torvalds from its own cache or by asking the net. 3231da177e4SLinus Torvalds 3241da177e4SLinus Torvalds This code is experimental and also obsolete. If you want to use it, 3251da177e4SLinus Torvalds you need to find a version of the daemon arpd on the net somewhere, 3261da177e4SLinus Torvalds and you should also say Y to "Kernel/User network link driver", 3271da177e4SLinus Torvalds below. If unsure, say N. 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvaldsconfig SYN_COOKIES 3301da177e4SLinus Torvalds bool "IP: TCP syncookie support (disabled per default)" 3311da177e4SLinus Torvalds ---help--- 3321da177e4SLinus Torvalds Normal TCP/IP networking is open to an attack known as "SYN 3331da177e4SLinus Torvalds flooding". This denial-of-service attack prevents legitimate remote 3341da177e4SLinus Torvalds users from being able to connect to your computer during an ongoing 3351da177e4SLinus Torvalds attack and requires very little work from the attacker, who can 3361da177e4SLinus Torvalds operate from anywhere on the Internet. 3371da177e4SLinus Torvalds 3381da177e4SLinus Torvalds SYN cookies provide protection against this type of attack. If you 3391da177e4SLinus Torvalds say Y here, the TCP/IP stack will use a cryptographic challenge 3401da177e4SLinus Torvalds protocol known as "SYN cookies" to enable legitimate users to 3411da177e4SLinus Torvalds continue to connect, even when your machine is under attack. There 3421da177e4SLinus Torvalds is no need for the legitimate users to change their TCP/IP software; 3431da177e4SLinus Torvalds SYN cookies work transparently to them. For technical information 3441da177e4SLinus Torvalds about SYN cookies, check out <http://cr.yp.to/syncookies.html>. 3451da177e4SLinus Torvalds 3461da177e4SLinus Torvalds If you are SYN flooded, the source address reported by the kernel is 3471da177e4SLinus Torvalds likely to have been forged by the attacker; it is only reported as 3481da177e4SLinus Torvalds an aid in tracing the packets to their actual source and should not 3491da177e4SLinus Torvalds be taken as absolute truth. 3501da177e4SLinus Torvalds 3511da177e4SLinus Torvalds SYN cookies may prevent correct error reporting on clients when the 3521da177e4SLinus Torvalds server is really overloaded. If this happens frequently better turn 3531da177e4SLinus Torvalds them off. 3541da177e4SLinus Torvalds 3551da177e4SLinus Torvalds If you say Y here, note that SYN cookies aren't enabled by default; 3561da177e4SLinus Torvalds you can enable them by saying Y to "/proc file system support" and 3571da177e4SLinus Torvalds "Sysctl support" below and executing the command 3581da177e4SLinus Torvalds 3591da177e4SLinus Torvalds echo 1 >/proc/sys/net/ipv4/tcp_syncookies 3601da177e4SLinus Torvalds 3611da177e4SLinus Torvalds at boot time after the /proc file system has been mounted. 3621da177e4SLinus Torvalds 3631da177e4SLinus Torvalds If unsure, say N. 3641da177e4SLinus Torvalds 3651da177e4SLinus Torvaldsconfig INET_AH 3661da177e4SLinus Torvalds tristate "IP: AH transformation" 3671da177e4SLinus Torvalds select XFRM 3681da177e4SLinus Torvalds select CRYPTO 3691da177e4SLinus Torvalds select CRYPTO_HMAC 3701da177e4SLinus Torvalds select CRYPTO_MD5 3711da177e4SLinus Torvalds select CRYPTO_SHA1 3721da177e4SLinus Torvalds ---help--- 3731da177e4SLinus Torvalds Support for IPsec AH. 3741da177e4SLinus Torvalds 3751da177e4SLinus Torvalds If unsure, say Y. 3761da177e4SLinus Torvalds 3771da177e4SLinus Torvaldsconfig INET_ESP 3781da177e4SLinus Torvalds tristate "IP: ESP transformation" 3791da177e4SLinus Torvalds select XFRM 3801da177e4SLinus Torvalds select CRYPTO 3811da177e4SLinus Torvalds select CRYPTO_HMAC 3821da177e4SLinus Torvalds select CRYPTO_MD5 3836b7326c8SHerbert Xu select CRYPTO_CBC 3841da177e4SLinus Torvalds select CRYPTO_SHA1 3851da177e4SLinus Torvalds select CRYPTO_DES 3861da177e4SLinus Torvalds ---help--- 3871da177e4SLinus Torvalds Support for IPsec ESP. 3881da177e4SLinus Torvalds 3891da177e4SLinus Torvalds If unsure, say Y. 3901da177e4SLinus Torvalds 3911da177e4SLinus Torvaldsconfig INET_IPCOMP 3921da177e4SLinus Torvalds tristate "IP: IPComp transformation" 3931da177e4SLinus Torvalds select XFRM 394d2acc347SHerbert Xu select INET_XFRM_TUNNEL 3951da177e4SLinus Torvalds select CRYPTO 3961da177e4SLinus Torvalds select CRYPTO_DEFLATE 3971da177e4SLinus Torvalds ---help--- 3981da177e4SLinus Torvalds Support for IP Payload Compression Protocol (IPComp) (RFC3173), 3991da177e4SLinus Torvalds typically needed for IPsec. 4001da177e4SLinus Torvalds 4011da177e4SLinus Torvalds If unsure, say Y. 4021da177e4SLinus Torvalds 403d2acc347SHerbert Xuconfig INET_XFRM_TUNNEL 404d2acc347SHerbert Xu tristate 405d2acc347SHerbert Xu select INET_TUNNEL 406d2acc347SHerbert Xu default n 4071da177e4SLinus Torvalds 408d2acc347SHerbert Xuconfig INET_TUNNEL 409d2acc347SHerbert Xu tristate 410d2acc347SHerbert Xu default n 4111da177e4SLinus Torvalds 412b59f45d0SHerbert Xuconfig INET_XFRM_MODE_TRANSPORT 413b59f45d0SHerbert Xu tristate "IP: IPsec transport mode" 414b59f45d0SHerbert Xu default y 415b59f45d0SHerbert Xu select XFRM 416b59f45d0SHerbert Xu ---help--- 417b59f45d0SHerbert Xu Support for IPsec transport mode. 418b59f45d0SHerbert Xu 419b59f45d0SHerbert Xu If unsure, say Y. 420b59f45d0SHerbert Xu 421b59f45d0SHerbert Xuconfig INET_XFRM_MODE_TUNNEL 422b59f45d0SHerbert Xu tristate "IP: IPsec tunnel mode" 423b59f45d0SHerbert Xu default y 424b59f45d0SHerbert Xu select XFRM 425b59f45d0SHerbert Xu ---help--- 426b59f45d0SHerbert Xu Support for IPsec tunnel mode. 427b59f45d0SHerbert Xu 428b59f45d0SHerbert Xu If unsure, say Y. 429b59f45d0SHerbert Xu 4300a69452cSDiego Beltramiconfig INET_XFRM_MODE_BEET 4310a69452cSDiego Beltrami tristate "IP: IPsec BEET mode" 4320a69452cSDiego Beltrami default y 4330a69452cSDiego Beltrami select XFRM 4340a69452cSDiego Beltrami ---help--- 4350a69452cSDiego Beltrami Support for IPsec BEET mode. 4360a69452cSDiego Beltrami 4370a69452cSDiego Beltrami If unsure, say Y. 4380a69452cSDiego Beltrami 43917b085eaSArnaldo Carvalho de Meloconfig INET_DIAG 44017b085eaSArnaldo Carvalho de Melo tristate "INET: socket monitoring interface" 4411da177e4SLinus Torvalds default y 4421da177e4SLinus Torvalds ---help--- 44373c1f4a0SArnaldo Carvalho de Melo Support for INET (TCP, DCCP, etc) socket monitoring interface used by 44473c1f4a0SArnaldo Carvalho de Melo native Linux tools such as ss. ss is included in iproute2, currently 445f4b9479dSBaruch Even downloadable at <http://linux-net.osdl.org/index.php/Iproute2>. 4461da177e4SLinus Torvalds 4471da177e4SLinus Torvalds If unsure, say Y. 4481da177e4SLinus Torvalds 44917b085eaSArnaldo Carvalho de Meloconfig INET_TCP_DIAG 45017b085eaSArnaldo Carvalho de Melo depends on INET_DIAG 45117b085eaSArnaldo Carvalho de Melo def_tristate INET_DIAG 45217b085eaSArnaldo Carvalho de Melo 4533d2573f7SStephen Hemmingermenuconfig TCP_CONG_ADVANCED 454a6484045SDavid S. Miller bool "TCP: advanced congestion control" 455a6484045SDavid S. Miller ---help--- 456a6484045SDavid S. Miller Support for selection of various TCP congestion control 457a6484045SDavid S. Miller modules. 458a6484045SDavid S. Miller 459a6484045SDavid S. Miller Nearly all users can safely say no here, and a safe default 460597811ecSStephen Hemminger selection will be made (CUBIC with new Reno as a fallback). 461a6484045SDavid S. Miller 462a6484045SDavid S. Miller If unsure, say N. 463a6484045SDavid S. Miller 4643d2573f7SStephen Hemmingerif TCP_CONG_ADVANCED 46583803034SStephen Hemminger 46683803034SStephen Hemmingerconfig TCP_CONG_BIC 46783803034SStephen Hemminger tristate "Binary Increase Congestion (BIC) control" 468597811ecSStephen Hemminger default m 46983803034SStephen Hemminger ---help--- 47083803034SStephen Hemminger BIC-TCP is a sender-side only change that ensures a linear RTT 47183803034SStephen Hemminger fairness under large windows while offering both scalability and 47283803034SStephen Hemminger bounded TCP-friendliness. The protocol combines two schemes 47383803034SStephen Hemminger called additive increase and binary search increase. When the 47483803034SStephen Hemminger congestion window is large, additive increase with a large 47583803034SStephen Hemminger increment ensures linear RTT fairness as well as good 47683803034SStephen Hemminger scalability. Under small congestion windows, binary search 47783803034SStephen Hemminger increase provides TCP friendliness. 47883803034SStephen Hemminger See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/ 47983803034SStephen Hemminger 480df3271f3SStephen Hemmingerconfig TCP_CONG_CUBIC 481df3271f3SStephen Hemminger tristate "CUBIC TCP" 482597811ecSStephen Hemminger default y 483df3271f3SStephen Hemminger ---help--- 484df3271f3SStephen Hemminger This is version 2.0 of BIC-TCP which uses a cubic growth function 485df3271f3SStephen Hemminger among other techniques. 486df3271f3SStephen Hemminger See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf 487df3271f3SStephen Hemminger 48887270762SStephen Hemmingerconfig TCP_CONG_WESTWOOD 48987270762SStephen Hemminger tristate "TCP Westwood+" 49087270762SStephen Hemminger default m 49187270762SStephen Hemminger ---help--- 49287270762SStephen Hemminger TCP Westwood+ is a sender-side only modification of the TCP Reno 49387270762SStephen Hemminger protocol stack that optimizes the performance of TCP congestion 49487270762SStephen Hemminger control. It is based on end-to-end bandwidth estimation to set 49587270762SStephen Hemminger congestion window and slow start threshold after a congestion 49687270762SStephen Hemminger episode. Using this estimation, TCP Westwood+ adaptively sets a 49787270762SStephen Hemminger slow start threshold and a congestion window which takes into 49887270762SStephen Hemminger account the bandwidth used at the time congestion is experienced. 49987270762SStephen Hemminger TCP Westwood+ significantly increases fairness wrt TCP Reno in 50087270762SStephen Hemminger wired networks and throughput over wireless links. 50187270762SStephen Hemminger 502a7868ea6SBaruch Evenconfig TCP_CONG_HTCP 503a7868ea6SBaruch Even tristate "H-TCP" 504a7868ea6SBaruch Even default m 505a7868ea6SBaruch Even ---help--- 506a7868ea6SBaruch Even H-TCP is a send-side only modifications of the TCP Reno 507a7868ea6SBaruch Even protocol stack that optimizes the performance of TCP 508a7868ea6SBaruch Even congestion control for high speed network links. It uses a 509a7868ea6SBaruch Even modeswitch to change the alpha and beta parameters of TCP Reno 510a7868ea6SBaruch Even based on network conditions and in a way so as to be fair with 511a7868ea6SBaruch Even other Reno and H-TCP flows. 512a7868ea6SBaruch Even 513a628d29bSJohn Heffnerconfig TCP_CONG_HSTCP 514a628d29bSJohn Heffner tristate "High Speed TCP" 5156a2e9b73SSam Ravnborg depends on EXPERIMENTAL 516a628d29bSJohn Heffner default n 517a628d29bSJohn Heffner ---help--- 518a628d29bSJohn Heffner Sally Floyd's High Speed TCP (RFC 3649) congestion control. 519a628d29bSJohn Heffner A modification to TCP's congestion control mechanism for use 520a628d29bSJohn Heffner with large congestion windows. A table indicates how much to 521a628d29bSJohn Heffner increase the congestion window by when an ACK is received. 522a628d29bSJohn Heffner For more detail see http://www.icir.org/floyd/hstcp.html 523a628d29bSJohn Heffner 524835b3f0cSDaniele Lacameraconfig TCP_CONG_HYBLA 525835b3f0cSDaniele Lacamera tristate "TCP-Hybla congestion control algorithm" 5266a2e9b73SSam Ravnborg depends on EXPERIMENTAL 527835b3f0cSDaniele Lacamera default n 528835b3f0cSDaniele Lacamera ---help--- 529835b3f0cSDaniele Lacamera TCP-Hybla is a sender-side only change that eliminates penalization of 530835b3f0cSDaniele Lacamera long-RTT, large-bandwidth connections, like when satellite legs are 53144c09201SMatt LaPlante involved, especially when sharing a common bottleneck with normal 532835b3f0cSDaniele Lacamera terrestrial connections. 533835b3f0cSDaniele Lacamera 534b87d8561SStephen Hemmingerconfig TCP_CONG_VEGAS 535b87d8561SStephen Hemminger tristate "TCP Vegas" 5366a2e9b73SSam Ravnborg depends on EXPERIMENTAL 537b87d8561SStephen Hemminger default n 538b87d8561SStephen Hemminger ---help--- 539b87d8561SStephen Hemminger TCP Vegas is a sender-side only change to TCP that anticipates 540b87d8561SStephen Hemminger the onset of congestion by estimating the bandwidth. TCP Vegas 541b87d8561SStephen Hemminger adjusts the sending rate by modifying the congestion 542b87d8561SStephen Hemminger window. TCP Vegas should provide less packet loss, but it is 543b87d8561SStephen Hemminger not as aggressive as TCP Reno. 544b87d8561SStephen Hemminger 5450e57976bSJohn Heffnerconfig TCP_CONG_SCALABLE 5460e57976bSJohn Heffner tristate "Scalable TCP" 5476a2e9b73SSam Ravnborg depends on EXPERIMENTAL 5480e57976bSJohn Heffner default n 5490e57976bSJohn Heffner ---help--- 5500e57976bSJohn Heffner Scalable TCP is a sender-side only change to TCP which uses a 5510e57976bSJohn Heffner MIMD congestion control algorithm which has some nice scaling 5520e57976bSJohn Heffner properties, though is known to have fairness issues. 553f4b9479dSBaruch Even See http://www.deneholme.net/tom/scalable/ 554a7868ea6SBaruch Even 5557c106d7eSWong Hoi Sing Edisonconfig TCP_CONG_LP 5567c106d7eSWong Hoi Sing Edison tristate "TCP Low Priority" 5577c106d7eSWong Hoi Sing Edison depends on EXPERIMENTAL 5587c106d7eSWong Hoi Sing Edison default n 5597c106d7eSWong Hoi Sing Edison ---help--- 5607c106d7eSWong Hoi Sing Edison TCP Low Priority (TCP-LP), a distributed algorithm whose goal is 561cab00891SMatt LaPlante to utilize only the excess network bandwidth as compared to the 5627c106d7eSWong Hoi Sing Edison ``fair share`` of bandwidth as targeted by TCP. 5637c106d7eSWong Hoi Sing Edison See http://www-ece.rice.edu/networks/TCP-LP/ 5647c106d7eSWong Hoi Sing Edison 56576f10177SBin Zhouconfig TCP_CONG_VENO 56676f10177SBin Zhou tristate "TCP Veno" 56776f10177SBin Zhou depends on EXPERIMENTAL 56876f10177SBin Zhou default n 56976f10177SBin Zhou ---help--- 57076f10177SBin Zhou TCP Veno is a sender-side only enhancement of TCP to obtain better 57176f10177SBin Zhou throughput over wireless networks. TCP Veno makes use of state 57276f10177SBin Zhou distinguishing to circumvent the difficult judgment of the packet loss 57376f10177SBin Zhou type. TCP Veno cuts down less congestion window in response to random 57476f10177SBin Zhou loss packets. 57576f10177SBin Zhou See http://www.ntu.edu.sg/home5/ZHOU0022/papers/CPFu03a.pdf 57676f10177SBin Zhou 5773d2573f7SStephen Hemmingerchoice 5783d2573f7SStephen Hemminger prompt "Default TCP congestion control" 579597811ecSStephen Hemminger default DEFAULT_CUBIC 5803d2573f7SStephen Hemminger help 5813d2573f7SStephen Hemminger Select the TCP congestion control that will be used by default 5823d2573f7SStephen Hemminger for all connections. 5833d2573f7SStephen Hemminger 5843d2573f7SStephen Hemminger config DEFAULT_BIC 5853d2573f7SStephen Hemminger bool "Bic" if TCP_CONG_BIC=y 5863d2573f7SStephen Hemminger 5873d2573f7SStephen Hemminger config DEFAULT_CUBIC 5883d2573f7SStephen Hemminger bool "Cubic" if TCP_CONG_CUBIC=y 5893d2573f7SStephen Hemminger 5903d2573f7SStephen Hemminger config DEFAULT_HTCP 5913d2573f7SStephen Hemminger bool "Htcp" if TCP_CONG_HTCP=y 5923d2573f7SStephen Hemminger 5933d2573f7SStephen Hemminger config DEFAULT_VEGAS 5943d2573f7SStephen Hemminger bool "Vegas" if TCP_CONG_VEGAS=y 5953d2573f7SStephen Hemminger 5963d2573f7SStephen Hemminger config DEFAULT_WESTWOOD 5973d2573f7SStephen Hemminger bool "Westwood" if TCP_CONG_WESTWOOD=y 5983d2573f7SStephen Hemminger 5993d2573f7SStephen Hemminger config DEFAULT_RENO 6003d2573f7SStephen Hemminger bool "Reno" 6013d2573f7SStephen Hemminger 6023d2573f7SStephen Hemmingerendchoice 6033d2573f7SStephen Hemminger 6043d2573f7SStephen Hemmingerendif 60583803034SStephen Hemminger 606597811ecSStephen Hemmingerconfig TCP_CONG_CUBIC 6076c360767SDavid S. Miller tristate 608a6484045SDavid S. Miller depends on !TCP_CONG_ADVANCED 609a6484045SDavid S. Miller default y 610a6484045SDavid S. Miller 6113d2573f7SStephen Hemmingerconfig DEFAULT_TCP_CONG 6123d2573f7SStephen Hemminger string 6133d2573f7SStephen Hemminger default "bic" if DEFAULT_BIC 6143d2573f7SStephen Hemminger default "cubic" if DEFAULT_CUBIC 6153d2573f7SStephen Hemminger default "htcp" if DEFAULT_HTCP 6163d2573f7SStephen Hemminger default "vegas" if DEFAULT_VEGAS 6173d2573f7SStephen Hemminger default "westwood" if DEFAULT_WESTWOOD 6183d2573f7SStephen Hemminger default "reno" if DEFAULT_RENO 619597811ecSStephen Hemminger default "cubic" 6203d2573f7SStephen Hemminger 621cfb6eeb4SYOSHIFUJI Hideakiconfig TCP_MD5SIG 622cfb6eeb4SYOSHIFUJI Hideaki bool "TCP: MD5 Signature Option support (RFC2385) (EXPERIMENTAL)" 623cfb6eeb4SYOSHIFUJI Hideaki depends on EXPERIMENTAL 624cfb6eeb4SYOSHIFUJI Hideaki select CRYPTO 625cfb6eeb4SYOSHIFUJI Hideaki select CRYPTO_MD5 626cfb6eeb4SYOSHIFUJI Hideaki ---help--- 627cfb6eeb4SYOSHIFUJI Hideaki RFC2385 specifices a method of giving MD5 protection to TCP sessions. 628cfb6eeb4SYOSHIFUJI Hideaki Its main (only?) use is to protect BGP sessions between core routers 629cfb6eeb4SYOSHIFUJI Hideaki on the Internet. 630cfb6eeb4SYOSHIFUJI Hideaki 631cfb6eeb4SYOSHIFUJI Hideaki If unsure, say N. 632cfb6eeb4SYOSHIFUJI Hideaki 6331da177e4SLinus Torvaldssource "net/ipv4/ipvs/Kconfig" 6341da177e4SLinus Torvalds 635