acpid
This a completely flexible, totally extensible daemon for delivering ACPI events. It listens on a file (/proc/acpi/event) and when an event occurs, executes programs to handle the event.
ACPI stands for: Advanced Configuration and Power Interface.
aep1000
For AEP 1000 coprocessors. It's used for hardware cryptographic acceleration under Linux.
anacron
Anacron is a periodic command scheduler. It executes commands at intervals specified in days. Unlike cron, it does not assume that the system is running continuously.
Every time Anacron is run, it reads a configuration file that specifies the jobs Anacron controls, and their periods in days. If a job wasn't executed in the last n days, where n is the period of that job, Anacron executes it. Anacron then records the date in a special timestamp file that it keeps for each job, so it can know when to run it again
apmd
The apmd package is a set of user-level programs to control the Advanced Power Management system found in all modern laptop computers and most modern desktops. apmd talks to the Linux kernel APM layer, which does all the hardware-dependent stuff.
atd
atd runs jobs queued by at.
autofs
Auto-autofs detects Disks, Partitions, CD-ROMs, Floppies etc. and sets up an automount configuration.
So it provides an easy access to the hardware.
Auto-autofs is a Perl script that searches the hardware for block devices using the /proc directory. It finds partitions on harddisks via fdisk and tries to detect the filesystems.
bcm5820
Hardware cryptographic accelerator support for Broadcom BCM5820 eCommerce Processor.
chargen
Character Generator Protocol.
A useful debugging and measurement tool is a character generator service. A character generator service simply sends data without regard to the input. Listens on port 19 TCP/UDP.
Details: http://www.networksorcery.com/enp/RFC/Rfc864.txt
chargen-udp
See chargen.
crond
Daemon to execute scheduled commands.
cups
The Common UNIX Printing System ("CUPS") is a cross-platform printing solution for all UNIX environments. It is based on the "Internet Printing Protocol" and provides complete printing services to most PostScript and raster printers.
cups-lpd
This is the CUPS Line Printer Daemon ("LPD") mini-server that supports legacy client systems that use the LPD protocol.
daytime The Daytime Protocol (Internet RFC 867) is a simple protocol that allows clients to retrieve the current date and time from a remote server. While useful at a bsic level, the Daytime protocol is most often used for debugging purposes rather than actually acquire the current date and time. The daytime protocol is available on TCP port 13.
daytime-udp
See daytime.
echo
Service for testing, everything you send to port 7 (echo) would be sent back to you.
echo-udp
see echo
gpm
General Purpose Mouse Daemon. Necessary only if you want to use your mouse on the console (not xterms).
httpd
The apache web server.
iptables
firewall
irda
(Infrared Data Association) is an industry standard for infrared wireless communication.
irqbalance
Daemon to balance irq's across multiple CPUs. Only useful on SMP systems (more than one processor)
isdn
ISDN (Integrated Services Digital Network). Use only with ISDN network interfaces.
ktalk
A graphical talk client for KDE.
kudzu
Detects and configures new and/or changed hardware on a system.
lisa
LISa is a small daemon which is intended to run on end user systems. It provides something like a "network neighborhood", but only relying on the TCP/IP protocol stack, no smb or whatever.
The information about the hosts in your "neighborhood" is provided via TCP port 7741.
To use it: from a client computer, open konqueror and type lan://targetIP
More information: http://lisa-home.sourceforge.net/
messagebus
D-BUS is first a library that provides one-to-one communication between any two applications; dbus-daemon-1 is an application that uses this library to implement a message bus daemon. Multiple programs connect to the message bus daemon and can exchange messages with one another.
More information: http://www.freedesktop.org/software/dbus/doc/dbus-daemon-1.1.html
microcode_ctl
It decodes and sends new microcode to the kernel driver to be uploaded to Intel IA32 processors. (Pentium Pro, PII, PIII, Pentium 4, Celeron, Xeon etc - all P6 and above, which does NOT include pentium classics)
It signals the kernel driver to release any buffers it may hold.
The microcode update is volatile and needs to be uploaded on each system boot i.e. it doesn't reflash your cpu permanently, reboot and it reverts back to the old microcode.
This driver is designed for Intel IA32 microprocessors only, it will not work with AMD or any other non-Intel processors as they don't support microcode updates or they support it in a manner different from Intel's specs.
More information: http://www.urbanmyth.org/microcode/   http://microcodes.sourceforge.net/
mysqld
MySQL database server.
named
DNS server. Bind.
netfs
Network Filesystem Mounter. Needed for mounting NFS, SMB and NCP shares on boot.
network
Activates all network interfaces at boot time.
nfslock
To help manage file access conflicts and protect NFS sessions during failures, NFS offers a file and record locking service called the network lock manager. The network lock manager is a separate service NFS makes available to user applications. To use the locking service, applications must make calls to standard lock routines.
ntpd
The ntpd sets and maintains the system time of day in synchronism with Internet standard time servers. It is a complete implementation of the Network Time Protocol (NTP) version 4. Allows other computers to synchronize system time with your server.
pcmcia
PCMCIA cards.
portmap
The portmap service is a dynamic port assignment daemon for RPC services such as NIS and NFS.
postgresql
PostgreSQL database server.
random
Initialize kernel random number generator
rawdevices
Block devices.  Links hardware to devices that store data.
rhnsd
Red Hat Network Service. Informs you about official security and bug updates for your system.
rsync
Its just like rpc with much more features. Provides a very fast method for bringing remote files into sync.
saslauthd
SASL (Simple Authentication and Security Layer) authentication server. Server to allow others identify on this server.
sendmail
Mail server, allows to send emails using this machine as mail server.
services
An internal xinetd services, listing active services.
sgi_fam
File Alteration Monitor, provides an API that applications can use to be notified when specific files or directories are changed. For example, consider a graphical file manager, when the user removes a file thru the file manager, their changes are visible immediately.
smartd
Self Monitor Analysis and Reporting Technology System. Monitor you hard disk for failures.
smb
Samba, allows to share and access MS windows network.
snmpd
Simple Network Management protocol. A standard protocol for non-windows networks.
More information: http://www.ncsa.uiuc.edu/UserInfo/Resources/Hardware/IBMp690/IBM/usr/share/man/info/en_US/a_doc_lib/cmds/aixcmds5/snmpd.htm
snmptrapd
This is an SNMP application that recieves and logs SNMP TRAP and INFORM messages. Uses UDP port 162.
squid
Web proxy cache. http://www.squid-cache.org/
sshd
Secure Shell daemon, allows secure and remote logging to this machine.
syslog
Logs all system activities.
time
Retrieve the date and time from a host or hosts on the network and set the local system time TCP version.
time-udp
Retrieve the date and time from a host or hosts on the network and set the local system time UDP version.
tux
The TUX Web Server is an HTTP daemon for Linux . The TUX Web Server is different from other Web servers in that it runs partially from within the Linux kernel as a module, or kernel subsystem. Given sufficient networking cards, it enables direct scatter-gather direct memory access (DMA) and hardware-based TCP/IP checksums from the page cache (the Linux file data cache) directly to the network, avoiding extra data copies.
vncserver
VNC stands for Virtual Network Computing. It is remote control software which allows you to view and interact with one computer (the "server") using a simple program (the "viewer") on another computer anywhere on the Internet.
More  information: http://www.realvnc.com/
vsftpd
Secure FTP daemon.
More information: http://vsftpd.beasts.org/
winbind

Winbind is an nss switch module to map Windows NT Domain databases to Unix.
In combination with Samba and pam_ntdom, a Unix box will be able to integrate straight into a full Windows NT Domain environment, without needing a Unix Account database.
More information: http://www.samba.org/

xfs
The X font server (xfs) provides a standard mechanism for an X server to communicate with a font renderer, frequently running on a remote machine. It usually runs on TCP port 7100.
You need to be running xfs if you want a remote X terminal to be able to use fonts from your system, or if you want to use fonts that your X server doesn't understand (and the font server does).
xinetd
Service wrapper. xinetd is a replacement for inetd, the internet services daemon.
xinetd - eXtended InterNET services daemon - provides a good security against intrusion and reduces the risks of Denial of Services (DoS) attacks. Like the well known couple (inetd+tcpd), it enables the configuration of the access rights for a given machine.
More information: http://www.xinetd.org/
yum
yum is an automatic updater and package installer/remover for rpm systems.
It automatically computes dependencies and figures out what things should occur to install packages.
It makes it easier to maintain groups of machines without having to manually update each one using rpm.
More information: http://linux.duke.edu/projects/yum/

服务名称
含义
acpid
配置文件:/proc/acpi/event
预设端口:无
说明:Advanced Configuration and Power Interface,为替代传统的APM电源管理标准而推出的新型电源管理标准。
是否需要启动:如果你需要对电源进行管理,那就需要启动。
anacron
配置文件:/etc/anacron
预设端口:无
说明:一个自动化运行任务。Red Hat Linux 随带四个自动化任务的工具:cron、 anacron、at、和 batc。当你的Linux主机并不是全天候开机,这个anacron就可以帮你执行在“crontab”设定的时间内没有执行的工作。举例来说,当你的 主机在晚上12:00会自动关闭,但是偏偏crontab这个例行性工作是在4:00工作,这个时候例行性工作就不能起作用了。不过利用anacron就 能做到。
是否需要启动:如果主机已经24小时开机,而且运行了cron,那么这个守护程序就不需要启动了。
apmd
配置文件:/etc/sysconfig/apmd
预设端口:无
说明:Advanced Power Management,高级电源管理。传统的电源管理标准。一般系统都会同时支持APM和APMD两种标志,但系统加载时只需加载一个即可。对于笔记本电脑比较有用,可以了解系统的“电池电量”。
是否需要启动:如果我们使用的是台式电脑或一直开机的机型,就不需要使用这个守护程序。
atd
配置文件:/etc/at.allow,/etc/at.deny
预设端口:无
说明:一个自动化运行任务。
是否需要启动:通常需要启动。不过如果你一直使用cron,那么也可以不启动。
autofs
配置文件:/etc/rc.d/init.d/autofs
预设端口:无
说明:实现光盘、软盘的自动加载。
是否需要启动:一般不需要启动。
chargen
chargen-udp
预设端口:TCP/UDP 19
说明:Character Generator Protocol,一种网络服务,主要功能是提供类似远程打字的功能。
是否需要启动:为安全起见,尽量关闭这个服务。
cpuspeed
说明:监测系统空闲百分比,降低或加快CPU时钟速度和电压从而在系统空闲时将能源消耗降为最小,而在系统繁忙时最大化加快系统执行速度。
更多细节:
是否需要启动:需要启动。
crond
配置文件:/etc/crontab
预设端口:无
说明:用来执行例行性命令的守护程序。
是否需要启动:必须启动。
cups
配置文件:
CUPS服务器配置文件:/etc/cups/cupsd.conf
CUPS客户端配置文件:/etc/cups/client.conf
CUPS打印机配置文件:/etc/cups/printers.conf
CUPS中类(class)配置文件:/etc/cups/classes.conf
说明:Common UNIX Printing System,公共UNIX打印支持,为Linux提供打印功能。
是否需要启动:如果不安装打印机,就不需要启动。
cups-lpd
预设端口:无
说明:CUPS Line Printer Daemon ("LPD"),提供打印功能。
是否需要启动:如果不安装打印机,就不需要启动。
daytime
daytime-udp
预设端口:TCP 13
说明:Daytime协议(RFC867)是一个简单的协议,为客户机实现从远程服务器获取日期和时间的功能。
是否需要启动:不用启动。
echo
echo-udp
预设端口:7
说明:服务器回显客户数据服务。
是否需要启动:不用启动。
gpm
配置文件:/etc/sysconfig/mouse
预设端口:无
说明:General Purpose Mouse Daemon ,gpm为文本模式下的Linux程序如mc(Midnight Commander)提供了鼠标的支持。它也支持控制台下鼠标 的拷贝,粘贴操作以及弹出式菜单。
是否需要启动:没必要的话,建议不要启动。
iptables
说明:防火墙。
是否需要启动:必须启动。
irda
Infrared Data Association,是一个实现红外无线数据传输的工业标准。
irqbalance
对多个系统处理器环境下的系统中断请求进行负载平衡的守护程序。
是否需要启动:如果你只安装了一个CPU,就不需要加载这个守护程序。
isdn
Integrated Services Digital Network,综合数字服务网络。提供对isdn设备的支持。
kudzu
配置文件:
/etc/sysconfig/hwconf
/etc/sysconfig/kudzu
说明:硬件自动检测 程序,会自动检测硬件是否发生变动,并相应进行硬件的添加、删除工作。当系统启动时,kudzu会对当前的硬件进行检测,并且和存储在 /etc/sysconfig/hwconf中的硬件信息进行一一对照,如果某个硬件从系统中被添加或者删除时,那么kudzu就会察觉到,并且通知用户 是否进行相关配置,然后修改/etc/sysconfig/hwconf,使硬件资料与系统保持同步。如果/etc/sysconfig/hwconf这 个文件不存在,那么kudzu将会从/etc/modprobe.conf,/etc/sysconfig/network-scripts/和 /etc/X11/XF86Config中探测已经存在的硬件。
是否需要启动:如果启动kudzu,则每次启动系统,都会检查新硬件(checking new hardware),会延长系统启动的时间。如果你不打算增加新硬件,那么就可以关闭这个启动服务,以加快系统启动时间。
mdmonitor
与RAID设备相关的守护程序。
mdmpd
与RAID设备相关的守护程序。
messagebus
D-BUS是一个库,为两个或两个以上的应用程序提供一对一的通讯。
dbus-daemon-1是一个应用程序,它使用这个库来实现messagebus守护程序。多个应用程序通过连接messagebus守护程序可以实现与其他程序交换信息。
更多细节:
microcode_ctl
可以编码以及发送新的微代码到kernel以更新Intel IA32系列处理器(Pentium Pro,PII,PIII,Pentium 4,Celeron, Xeon 等等 – 全部 P6 以及更高,不包括 pentium classics)。
更多细节:
netdump
News Backup Dump Server,远程备份服务器。
netfs
Network Filesystem Mounter,安装和卸载NFS、SAMBA和NCP网络文件系统。
netplugd
配置文件:
/etc/netplug/netplugd.conf
/etc/netplug.d/netplug
说明:network cable hotplug management daemon,netplugd是一个守护程序,可以监控一个或多个网络接口的状态,当某些事件触发时运行一个外部脚本程序。
network
在系统启动时激活所有的网络接口。
nfs
网络文件系统。
nfslock
NFS是一个流行的通过TCP/IP网络共享文件的协议,此服务提供了NFS文件锁定功能。
ntpd
配置文件:/etc/ntp.conf
说明:Network time Protocol daemon,网络时间校正协议。简单的说,NTP是用来使系统和一个精确的时间源保持时间同步的协议。
推荐大家看一篇文章:《NTP-让网络里的电脑时间精确到毫秒》
发表在2004年12月份的《在线技术》杂志第63页
pcmcia
Pcmcia卡,支持笔记本电脑的PCMCIA 设备,如调制解调器, 网络适配器, SCSI卡等等。
portmap
Portmap守护程序为RPC服务,如NIS和NFS提供动态端口的分配。
psacct
包括几个工具用来监控进程活动的工具,包括ac,lastcomm, accton 和sa。
random
说明:快速的将系统的状态在随机的时间内存到景象档案中,对于系统相当重要。因为在开机之后,系统会迅速的恢复到开机之前的状态。
是否需要启动:必须启动。
rawdevices
在使用集群文件系统时用于加载raw设备的守护程序。
readahead
readahead_early
配置文件:/etc/readahead.early.files  /etc/readahead.files
说明:readahead和readahead_early是在Fedora core 2中最新推出的两个后台运行的守护程序。其作用是在启动系统期间,将启动系统所要用到的文件首先读取到内存中,然后在内存中进行执行,以加快系统的启动速 度。而上面两个配置文件就保存着将要读取到内存的文件列表。
rhnsd
Red Hat 网络服务。通知你有关官方的安全信息以及为你的系统打补丁。
rpcgssd
rpcidmapd
rpcsrcgssd
说明:gestion NFS v4,是Linux 2.6内核新添的功能。
是否需要启动:不需要启动。
rsync
remote sync,远程数据备份工具。
saslauthd
使用SASL的认证守护程序。
sendmail
邮件服务器。
services
一个内部xinetd服务,用于监听活动的服务。
sgi-fam
实现实时数据镜像。监控文件的变更,提供一个应用程序API接口用来当指定的文件火目录改变时及时通知。
smartd
Self Monitor Analysis and Reporting Technology System,监控你的硬盘是否出现故障。
sshd
配置文件:
OpenSSH服务器配置文件:/etc/ssh/sshd_config
OpenSSH客户端配置文件:/etc/ssh/ssh_config
预设端口:22
说明:Secure Shell Protocol,实现安全地远程登陆管理主机。
是否需要启动:如果想实现远程管理,就需要启动。
syslog
配置文件:/etc/syslog.conf
说明:记录所有的系统行为。
是否需要启动:必须启动。
time
从远程主机获取时间和日期,采用TCP协议。
time-udp
从远程主机获取时间和日期,采用UDP协议。
vncserver
VNC (Virtual Network Computing,虚拟网络计算),它提供了一种在本地系统上显示远程计算机整个“桌面”的轻量型协议。
xfs
预设端口:TCP 7100
说明:x font server,X Window字型服务器,为本地和远程X服务器提供字型集。
是否需要启动:如果使用run-level为5的图形界面,那么就需要启动。
xinetd
配置文件:/etc/xinetd.conf
说明:xinetd作为inetd的后续版本,负责管理系统中不频繁使用的服务,这些服务程序在有请求时才由xinetd服务负责启动运行,一 旦完成服务请求服务程序结束运行,这样可以有效地减少对系统资源的占用率。通常,xinetd管理的程序有telnet、ftp、rsh和rlogin。 关闭inetd也就关闭了这些由它管理的服务。
更多细节:http://www.xinetd.org/
是否需要启动:必须启动。
yum
配置文件:/etc/yum.conf
说明:Yellow Dog UpdaterModified,是一个自动更新、安装和删除RPM软件包的管理程序,它会自动计算软件包的管理程序,并判断哪些软件应该安装,哪些软件则不必安装。
是否需要启动:以系统管理策略而决定是否启动