Red Hat ENTERPRISE LINUX 3 Reference Manual page 92

74
dresses, respectively. A value of
packets.
• ip_default_ttl
may make before reaching its destination. Increasing this value can diminish system performance.
— Permits interfaces on the system to forward packets to one other. By default, this
• ip_forward
file is set to . Setting this file to
0
• ip_local_port_range
port is needed. The first number is the lowest port to be used and the second number specifies the
highest port. Any systems that expect to require more ports than the default 1024 to 4999 should
use a range from 32768 to 61000.
• tcp_syn_retries
packet when attempting to make a connection.
— Sets the number of permitted re-transmissions attempting to answer an incom-
• tcp_retries1
ing connection. Default of
— Sets the number of permitted re-transmissions of TCP packets. Default of
•
tcp_retries2
The
/usr/src/linux-2.4/Documentation/networking/ip-sysctl.txt
plete list of files and options available in the
A number of other directories exist within the
different aspect of the network stack. The
tem interface to be configured in different ways, including the use of default settings for unconfigured
devices (in the
/proc/sys/net/ipv4/conf/default/
special configurations (in the
The
/proc/sys/net/ipv4/neigh/
rectly connected to the system (called a network neighbor) and also contains different settings for
systems more than one hop away.
Routing over IPV4 also has its own directory,
, the
neigh/ /proc/sys/net/ipv4/route/
ing with any interfaces on the system. Many of these settings, such as
, relate to controlling the size of the routing cache. To clear the routing cache, write any
min_delay
value to the file.
flush
Additional information about these directories and the possible values for their configuration files can
be found in:
/usr/src/linux-2.4/Documentation/filesystems/proc.txt
5.3.9.5.
/proc/sys/vm/
This directory facilitates the configuration of the Linux kernel's virtual memory (VM) subsystem. The
kernel makes extensive and intelligent use of virtual memory, which is commonly called swap space.
The following files are commonly found in the
— Sets values related to the
•
bdflush
— Sets values for the kernel swap-out daemon,
•
kswapd
512 32 8
The first value sets the maximum number of pages that
The larger this number, the more aggressively the kernel can move to free pages. The second value
sets the minimum number of times that
number of pages
kswapd
allows the kernel to respond, while a value of
0
— Sets the default Time To Live (TTL), which limits the number of hops a packet
enables network packet forwarding.
1
— Specifies the range of ports to be used by TCP or UDP when a local
— Provides a limit on the number of times the system re-transmits a SYN
.
3
/proc/sys/net/ipv4/conf/
/proc/sys/net/ipv4/conf/all/
directory contains settings for communicating with a host di-
bdflush
attempts to write in a single attempt. Proper tuning of this final value can
/proc/sys/net/ipv4/
/proc/sys/net/ipv4/
subdirectory) and settings that override all
/proc/sys/net/ipv4/route/
directory contains specifications that apply to rout-
/proc/sys/vm/
kernel daemon.
kswapd
kswapd
attempts to free a page. The third value sets the
kswapd
proc
Chapter 5. The
file contains a com-
directory.
directory and each covers a
directory allows each sys-
subdirectory).
. Unlike
,
max_size max_delay
directory:
. This file has three values:
attempts to free in a single attempt.
File System
ignores the
1
.
15
and
conf/
, and