#
# IP configuration
#
config IP_MULTICAST
bool "IP: multicasting"
help
This is code for addressing several networked computers at once,
enlarging your kernel by about 2 KB. You need multicasting if you
intend to participate in the MBONE, a high bandwidth network on top
of the Internet which carries audio and video broadcasts. More
information about the MBONE is on the WWW at
<http://www-itg.lbl.gov/mbone/>. Information about the multicast
capabilities of the various network cards is contained in
<file:Documentation/networking/multicast.txt>. For most people, it's
safe to say N.
config IP_ADVANCED_ROUTER
bool "IP: advanced router"
---help---
If you intend to run your Linux box mostly as a router, i.e. as a
computer that forwards and redistributes network packets, say Y; you
will then be presented with several options that allow more precise
control about the routing process.
The answer to this question won't directly affect the kernel:
answering N will just cause the configurator to skip all the
questions about advanced routing.
Note that your box can only act as a router if you enable IP
forwarding in your kernel; you can do that by saying Y to "/proc
file system support" and "Sysctl support" below and executing the
line
echo "1" > /proc/sys/net/ipv4/ip_forward
at boot time after the /proc file system has been mounted.
If you turn on IP forwarding, you will also get the rp_filter, which
automatically rejects incoming packets if the routing table entry
for their source address doesn't match the network interface they're
arriving on. This has security advantages because it prevents the
so-called IP spoofing, however it can pose problems if you use
asymmetric routing (packets from you to a host take a different path
than packets from that host to you) or if you operate a non-routing
host which has several IP addresses on different interfaces. To turn
rp_filter off use:
echo 0 > /proc/sys/net/ipv4/conf/<device>/rp_filter
or
echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter
If unsure, say N here.
choice
prompt "Choose IP: FIB lookup algorithm (choose FIB_HASH if unsure)"
depends on IP_ADVANCED_ROUTER
default ASK_IP_FIB_HASH
config ASK_IP_FIB_HASH
bool "FIB_HASH"
---help---
Current FIB is very proven and good enough for most users.
config IP_FIB_TRIE
bool "FIB_TRIE"
---help---
Use new experimental LC-trie as FIB lookup algoritm.
This improves lookup performance if you have a large
number of routes.
LC-trie is a longest matching prefix lookup algorithm which
performs better than FIB_HASH for large routing tables.
But, it consumes more memory and is more complex.
LC-trie is described in:
IP-address lookup using LC-tries. Stefan Nilsson and Gunnar Karlsson
IEEE Journal on Selected Areas in Communications, 17(6):1083-1092, June 1999
An experimental study of compression methods for dynamic tries
Stefan Nilsson and Matti Tikkanen. Algorithmica, 33(1):19-33, 2002.
http://www.nada.kth.se/~snilsson/public/papers/dyntrie2/
endchoice
config IP_FIB_HASH
def_bool ASK_IP_FIB_HASH || !IP_ADVANCED_ROUTER
config IP_MULTIPLE_TABLES
bool "IP: policy routing"
depends on IP_ADVANCED_ROUTER
---help---
Normally, a router decides what to do with a received packet based
solely on the packet's final destination address. If you say Y here,
the Linux router will also be able to take the packet's source
address into account. Furthermore, the TOS (Type-Of-Service) field
of the packet can be used for routing decisions as well.
If you are interested in this, please see the preliminary
documentation at <http://www.compendium.com.ar/policy-routing.txt>
and <ftp://post.tepkom.ru/pub/vol2/Linux/docs/advanced-routing.tex>.
You will need supporting software from
<ftp://ftp.tux.org/pub/net/ip-routing/>.
If unsure, say N.
config IP_ROUTE_FWMARK
bool "IP: use netfilter MARK value as routing key"
depends on IP_MULTIPLE_TABLES && NETFILTER
help
If you say Y here, you will be able to specify different routes for
packets with different mark values (see iptables(8), MARK target).
config IP_ROUTE_MULTIPATH
bool "IP: equal cost multipath"
depends on IP_ADVANCED_ROUTER
help
Normally, the routing tables specify a single action to be taken in
a deterministic manner for a given packet. If you say Y here
however, it becomes possible to attach several actions to a packet
pattern, in effect specifying several alternative paths to travel
for those packets. The router considers all these paths to be of
equal "cost" and chooses one of them in a non-deterministic fashion
if a matching packet arrives.
config IP_ROUTE_MULTIPATH_CACHED
bool "IP: equal cost multipath with caching support (EXPERIMENTAL)"
depends on IP_ROUTE_MULTIPATH
help
Normally, equal cost multipath routing is not supported by the
routing cache. If you say Y here, alternative routes are cached
and on cache lookup a route is chosen in a configurable fashion.
If unsure, say N.
config IP_ROUTE_MULTIPATH_RR
tristate "MULTIPATH: round robin algorithm"
depends on IP_ROUTE_MULTIPATH_CACHED
help
Mulitpath routes are chosen according to Round Robin
config IP_ROUTE_MULTIPATH_RANDOM
tristate "MULTIPATH: random algorithm"
depends on IP_ROUTE_MULTIPATH_CACHED
help
Multipath routes are chosen in a random fashion. Actually,
there is no weight for a route. The advantage of this policy
is that it is implemented stateless and therefore introduces only
a very small delay.
config IP_ROUTE_MULTIPATH_WRANDOM
tristate "MULTIPATH: weighted random algorithm"
depends on IP_ROUTE_MULTIPATH_CACHED
help
Multipath routes are chosen in a weighted random fashion.
The per route weights are the weights visible via ip route 2. As the
corresponding state management introduces some overhead routing delay
is increased.
config IP_ROUTE_MULTIPATH_DRR
tristate "MULTIPATH: interface round robin algorithm"
depends on IP_ROUTE_MULTIPATH_CACHED
help
Connections are distributed in a round robin fashion over the
available interfaces. This policy makes sense if the connections
should be primarily distributed on interfaces and not on routes.
config IP_ROUTE_VERBOSE
bool "IP: verbose route monitoring"
depends on IP_ADVANCED_ROUTER
help
If you say Y here, which is recommended, then the kernel will print
verbose messages regarding the routing, for example warnings about
received packets which look strange and could be evidence of an
attack or a misconfigured system somewhere. The information is
handled by the klogd daemon which is responsible for kernel messages
("man klogd").
config IP_PNP
bool "IP: kernel level autoconfiguration"
help
This enables automatic configuration of IP addresses of devices and
of the routing table during kernel boot, based on either information
supplied on the kernel command line or by BOOTP or RARP protocols.
You need to say Y only for diskless machines requiring network
access to boot (in which case you want to say Y to "Root file system
on NFS" as well), because all other machines configure the network
in their startup scripts.
config IP_PNP_DHCP
bool "IP: DHCP support"
depends on IP_PNP
---help---
If you want your Linux box to mount its whole root file system (the
one containing the directory /) from some other computer over the
net via NFS and you want the IP address of your computer to be
discovered automatically at boot time using the DHCP protocol (a
special protocol designed for doing this job), say Y here. In case
the boot ROM of your network card was designed for booting Linux and
does DHCP itself, providing all necessary information on the kernel
command line, you can say N here.
If unsure, say Y. Note that if you want to use DHCP, a DHCP server
must be operating on your network. Read
<file:Documentation/nfsroot.txt> for details.
config IP_PNP_BOOTP
bool "IP: BOOTP support"
depends on IP_PNP
---help---
If you want your Linux box to mount its whole root file system (the
one containing the directory /) from some other computer over the
net via NFS and you want the IP address of your computer to be
discovered automatically at boot time using the BOOTP protocol (a
special protocol designed for doing this job), say Y here. In case
the boot ROM of your network card was designed for booting Linux and
does BOOTP itself, providing all necessary information on the kernel
command line, you can say N here. If unsure, say Y. Note that if you
want to use BOOTP, a BOOTP server must be operating on your network.
Read <file:Documentation/nfsroot.txt> for details.
config IP_PNP_RARP
bool "IP: RARP support"
depends on IP_PNP
help
If you want your Linux box to mount its whole root file system (the
one containing the directory /) from some other computer over the
net via NFS and you want the IP address of your computer to be
discovered automatically at boot time using the RARP protocol (an
older protocol which is being obsoleted by BOOTP and DHCP), say Y
here. Note that if you want to use RARP, a RARP server must be
operating on your network. Read <file:Documentation/nfsroot.txt> for
details.
# not yet ready..
# bool ' IP: ARP support' CONFIG_IP_PNP_ARP
config NET_IPIP
tristate "IP: tunneling"
---help---
Tunneling means encapsulating data of one protocol type within
another protocol and sending it over a channel that understands the
encapsulating protocol. This particular tunneling driver implements
encapsulation of IP within IP, which sounds kind of pointless, but
can be useful if you want to make your (or some other) machine
appear on a different network than it physically is, or to use
mobile-IP facilities (allowing laptops to seamlessly move between
networks without changing their IP addresses).
Saying Y to this option will produce two modules ( = code which can
be inserted in and removed from the running kernel whenever you
want). Most people won't need this and can say N.
config NET_IPGRE
tristate "IP: GRE tunnels over IP"
help
Tunneling means encapsulating data of one protocol type within
another protocol and sending it over a channel that understands the
encapsulating protocol. This particular tunneling driver implements
GRE (Generic Routing Encapsulation) and at this time allows
encapsulating of IPv4 or IPv6 over existing IPv4 infrastructure.
This driver is useful if the other endpoint is a Cisco router: Cisco
likes GRE much better than the other Linux tunneling driver ("IP
tunneling" above). In addition, GRE allows multicast redistribution
through the tunnel.
config NET_IPGRE_BROADCAST
bool "IP: broadcast GRE over IP"
depends on IP_MULTICAST && NET_IPGRE
help
One application of GRE/IP is to construct a broadcast WAN (Wide Area
Network), which looks like a normal Ethernet LAN (Local Area
Network), but can be distributed all over the Internet. If you want
to do that, say Y here and to "IP multicast routing" below.
config IP_MROUTE
bool "IP: multicast routing"
depends on IP_MULTICAST
help
This is used if you want your machine to act as a router for IP
packets that have several destination addresses. It is needed on the
MBONE, a high bandwidth network on top of the Internet which carries
audio and video broadcasts. In order to do that, you would most
likely run the program mrouted. Information about the multicast
capabilities of the various network cards is contained in
<file:Documentation/networking/multicast.txt>. If you haven't heard
about it, you don't need it.
config IP_PIMSM_V1
bool "IP: PIM-SM version 1 support"
depends on IP_MROUTE
help
Kernel side support for Sparse Mode PIM (Protocol Independent
Multicast) version 1. This multicast routing protocol is used widely
because Cisco supports it. You need special software to use it
(pimd-v1). Please see <http://netweb.usc.edu/pim/> for more
information about PIM.
Say Y if you want to use PIM-SM v1. Note that you can say N here if
you just want to use Dense Mode PIM.
config IP_PIMSM_V2
bool "IP: PIM-SM version 2 support"
depends on IP_MROUTE
help
Kernel side support for Sparse Mode PIM version 2. In order to use
this, you need an experimental routing daemon supporting it (pimd or
gated-5). This routing protocol is not used widely, so say N unless
you want to play with it.
config ARPD
bool "IP: ARP daemon support (EXPERIMENTAL)"
depends on EXPERIMENTAL
---help---
Normally, the kernel maintains an internal cache which maps IP
addresses to hardware addresses on the local network, so that
Ethernet/Token Ring/ etc. frames are sent to the proper address on
the physical networking layer. For small networks having a few
hundred directly connected hosts or less, keeping this address
resolution (ARP) cache inside the kernel works well. However,
maintaining an internal ARP cache does not work well for very large
switched networks, and will use a lot of kernel memory if TCP/IP
connections are made to many machines on the network.
If you say Y here, the kernel's internal ARP cache will never grow
to more than 256 entries (the oldest entries are expired in a LIFO
manner) and communication will be attempted with the user space ARP
daemon arpd. Arpd then answers the address resolution request either
from its own cache or by asking the net.
This code is experimental and also obsolete. If you want to use it,
you need to find a version of the daemon arpd on the net somewhere,
and you should also say Y to "Kernel/User network link driver",
below. If unsure, say N.
config SYN_COOKIES
bool "IP: TCP syncookie support (disabled per default)"
---help---
Normal TCP/IP networking is open to an attack known as "SYN
flooding". This denial-of-service attack prevents legitimate remote
users from being able to connect to your computer during an ongoing
attack and requires very little work from the attacker, who can
operate from anywhere on the Internet.
SYN cookies provide protection against this type of attack. If you
say Y here, the TCP/IP stack will use a cryptographic challenge
protocol known as "SYN cookies" to enable legitimate users to
continue to connect, even when your machine is under attack. There
is no need for the legitimate users to change their TCP/IP software;
SYN cookies work transparently to them. For technical information
about SYN cookies, check out <http://cr.yp.to/syncookies.html>.
If you are SYN flooded, the source address reported by the kernel is
likely to have been forged by the attacker; it is only reported as
an aid in tracing the packets to their actual source and should not
be taken as absolute truth.
SYN cookies may prevent correct error reporting on clients when the
server is really overloaded. If this happens frequently better turn
them off.
If you say Y here, note that SYN cookies aren't enabled by default;
you can enable them by saying Y to "/proc file system support" and
"Sysctl support" below and executing the command
echo 1 >/proc/sys/net/ipv4/tcp_syncookies
at boot time after the /proc file system has been mounted.
If unsure, say N.
config INET_AH
tristate "IP: AH transformation"
select XFRM
select CRYPTO
select CRYPTO_HMAC
select CRYPTO_MD5
select CRYPTO_SHA1
---help---
Support for IPsec AH.
If unsure, say Y.
config INET_ESP
tristate "IP: ESP transformation"
select XFRM
select CRYPTO
select CRYPTO_HMAC
select CRYPTO_MD5
select CRYPTO_SHA1
select CRYPTO_DES
---help---
Support for IPsec ESP.
If unsure, say Y.
config INET_IPCOMP
tristate "IP: IPComp transformation"
select XFRM
select INET_TUNNEL
select CRYPTO
select CRYPTO_DEFLATE
---help---
Support for IP Payload Compression Protocol (IPComp) (RFC3173),
typically needed for IPsec.
If unsure, say Y.
config INET_TUNNEL
tristate "IP: tunnel transformation"
select XFRM
---help---
Support for generic IP tunnel transformation, which is required by
the IP tunneling module as well as tunnel mode IPComp.
If unsure, say Y.
config INET_DIAG
tristate "INET: socket monitoring interface"
default y
---help---
Support for INET (TCP, DCCP, etc) socket monitoring interface used by
native Linux tools such as ss. ss is included in iproute2, currently
downloadable at <http://developer.osdl.org/dev/iproute2>.
If unsure, say Y.
config INET_TCP_DIAG
depends on INET_DIAG
def_tristate INET_DIAG
config TCP_CONG_ADVANCED
bool "TCP: advanced congestion control"
---help---
Support for selection of various TCP congestion control
modules.
Nearly all users can safely say no here, and a safe default
selection will be made (BIC-TCP with new Reno as a fallback).
If unsure, say N.
# TCP Reno is builtin (required as fallback)
menu "TCP congestion control"
depends on TCP_CONG_ADVANCED
config TCP_CONG_BIC
tristate "Binary Increase Congestion (BIC) control"
default y
---help---
BIC-TCP is a sender-side only change that ensures a linear RTT
fairness under large windows while offering both scalability and
bounded TCP-friendliness. The protocol combines two schemes
called additive increase and binary search increase. When the
congestion window is large, additive increase with a large
increment ensures linear RTT fairness as well as good
scalability. Under small congestion windows, binary search
increase provides TCP friendliness.
See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
config TCP_CONG_WESTWOOD
tristate "TCP Westwood+"
default m
---help---
TCP Westwood+ is a sender-side only modification of the TCP Reno
protocol stack that optimizes the performance of TCP congestion
control. It is based on end-to-end bandwidth estimation to set
congestion window and slow start threshold after a congestion
episode. Using this estimation, TCP Westwood+ adaptively sets a
slow start threshold and a congestion window which takes into
account the bandwidth used at the time congestion is experienced.
TCP Westwood+ significantly increases fairness wrt TCP Reno in
wired networks and throughput over wireless links.
config TCP_CONG_HTCP
tristate "H-TCP"
default m
---help---
H-TCP is a send-side only modifications of the TCP Reno
protocol stack that optimizes the performance of TCP
congestion control for high speed network links. It uses a
modeswitch to change the alpha and beta parameters of TCP Reno
based on network conditions and in a way so as to be fair with
other Reno and H-TCP flows.
config TCP_CONG_HSTCP
tristate "High Speed TCP"
depends on EXPERIMENTAL
default n
---help---
Sally Floyd's High Speed TCP (RFC 3649) congestion control.
A modification to TCP's congestion control mechanism for use
with large congestion windows. A table indicates how much to
increase the congestion window by when an ACK is received.
For more detail see http://www.icir.org/floyd/hstcp.html
config TCP_CONG_HYBLA
tristate "TCP-Hybla congestion control algorithm"
depends on EXPERIMENTAL
default n
---help---
TCP-Hybla is a sender-side only change that eliminates penalization of
long-RTT, large-bandwidth connections, like when satellite legs are
involved, expecially when sharing a common bottleneck with normal
terrestrial connections.
config TCP_CONG_VEGAS
tristate "TCP Vegas"
depends on EXPERIMENTAL
default n
---help---
TCP Vegas is a sender-side only change to TCP that anticipates
the onset of congestion by estimating the bandwidth. TCP Vegas
adjusts the sending rate by modifying the congestion
window. TCP Vegas should provide less packet loss, but it is
not as aggressive as TCP Reno.
config TCP_CONG_SCALABLE
tristate "Scalable TCP"
depends on EXPERIMENTAL
default n
---help---
Scalable TCP is a sender-side only change to TCP which uses a
MIMD congestion control algorithm which has some nice scaling
properties, though is known to have fairness issues.
See http://www-lce.eng.cam.ac.uk/~ctk21/scalable/
endmenu
config TCP_CONG_BIC
tristate
depends on !TCP_CONG_ADVANCED
default y
source "net/ipv4/ipvs/Kconfig"
