abrtd (Automated Bug Reporting Tool) Daemon 用于自动向redhat 发送错误报告，windows好象也有这个功能喔。对于服务器来说，我建议把这个服务给关了。因为我的服务器不能通过外网主动向外发启连接（外网交换机上 有ACL）。为了安全，没办法哈。
acpid （ Advanced Configuration and Power Interface）电源管理接口服务，一般笔记本上会用到，服务器就不用了，关了。
atd 这个服务功能和crond 相似，但我一般只用crond,关了吧。
auditd 审核守护进程, 审核信息会被发送到一个用户配置日志文件中（默认的文件是 /var/log/audit/audit.log）。如果有审计要求，就开着吧。
cpuspeed 该服务可以在运行时动态调节 CPU 的频率来节约能源（省电）。我都不确认我服务器的CPU是否支持这个功能，但我还是愿意响应一下国家节能减排的号召，开一下 ：）。
crond 相当于windows里的计划任务，对我来说，是必开的。
haldaemon 硬件监控系统此服务监控硬件改变,一般是用来自动挂载移动硬盘用的.对于线上运行的服务器来说，硬件变更的机会非常的少，也不用自动挂载（而且会有安装问题），所以关了吧。
ip6tables 支持IPV6的iptables 防火墙，我的服务器还没有使用IPV6，所以可以把这个关了。
iptables 支持IPV4的iptables 防火墙，我的服务器在交换机层的ACL已经做的很好了，所以这个我也是关掉了。不过对大多数网络层ACL做得不是很好的用户来说，这个还是开着的好，呵呵。
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。现在还有单核的服务器吗？对我来说，必开哈。
kdump 内核转储服务，kdump会在系统内核崩溃时，启动第二个内核来记录当前内存信息。kdump的dump机制是：预先生成一个crashkernel，在 内核crash的时候，激活这个crashkernel，用这个crashkernel载入的小型系统dump处于crash状态的内核。有用，我反正是 开着的，这个功能在HP-UX及AIX等小机系统上都有的，对分析系统crash很有用。开着。
lvm2-monitor LVM2 (Linux volume manager) 监控服务，如果你没有什么LVM2，关了吧。
mdmonitor software RAID monitoring and management service,如果你没有使用软RAID，关了吧。上面的服务和这个服务是否启动，我个人觉得RHEL应该通过脚本来自动确认，而不应该默认就开着。
messagebus This service broadcasts notifications of system events and other messages (D-bus). 如果你不用 bluetooth, X Windows 等，就关了吧。
netfs Network Filesystem Mounter，该服务用于在系统启动时自动挂载网络中的共享文件空间。不用自动挂载，就关了吧。
network 网络服务，这个服务不开，网络就不可用，必开哈。
postfix 邮件服务，以前是sendmail,现在改成postfix,用启来更顺手了。默认是监听在127.0.0.1上的，可以开着。
rhnsd 连到RHN进行rhel系统更新。如果你用的是yum,就关了吧。我是关着的，原因你明白的。
rhsmcertd Red Hat Subscription Manager daemon,这个服务是RHEL6.1新加的，用于更好、更方便的使用RHN进行用户的软件升级和管理。上面的不用，下面当然也不用了。
rsyslog 系统日志，以前用的是syslogd,现在改成rsyslog了，由原来的UDP传输到现在支持TCP传输了。开着哈。
sshd sshd 服务，如果要进行远程管理和文件传输这是必须的。开着。
sysstat 使用sar来进行系统性能统计的服务，很好用，我是开着的。
qpid 是 Apache 开发的一款面向对象的消息中间件，它是一个 AMQP 的实现，可以和其他符合 AMQP 协议的系统进行通信。Qpid 提供了 C++/Python/Java/C# 等主流编程语言的客户端库，安装使用非常方便。相对于其他的 AMQP 实现，Qpid 社区十分活跃，有望成为标准 AMQP 中间件产品。除了符合 AMQP 基本要求之外，Qpid 提供了很多额外的 HA 特性，非常适于集群环境下的消息通信。
Recommend Actions on Default Services
| Service | Description | Action |
|---|---|---|
| acpid | Advanced Configuration and Power Interface event daemon | Enable |
| anacron | Anacron is like cron, but it does not assume that the machine is running continuously. Hence, it can be used on machines that aren’t running 24 hours a day, to control daily, weekly, and monthly jobs that are usually controlled by cron. | Disable on servers |
| apmd | Advanced Power Management Subsystem (old system). If the server is capable of ACPI support, disable this service | Disable if possible |
| auditd | The Linux Auditing System | Enable and configure |
| atd | atd runs jobs queued by at | Enable and configure |
| autofs | The automount(8) program is used to manage mount points for autofs, the inlined Linux automounter. You can mount NFS, USB, DVD/CD, and CIFS via /etc/fstab. | Disable |
| avahi-daemon and avahi-dnsconfd | The Avahi mDNS/DNS-SD daemon implementing Apple's ZeroConf architecture (also known as "Rendezvous" or "Bonjour"). | Disable |
| bluetooth and hidd | Bluetooth services for service discovery, authentication, Human Interface Devices (hidd), etc | Disable |
| cpuspeed | This service monitors the system’s idle percentage and reduces or raises the CPUs’ clock speeds and voltages accordingly to minimize power consumption when idle and maximize performance when needed | Enable |
| crond | Service to execute scheduled commands via crond daemon. | Enable and configure |
| cups | Common unix printing system service | Disable if possible |
| dc_client & dc_client | Startup script for the Distcache SSL Session Cache Client and server proxy. Disable if you do not need cache proxy. | Disable if possible |
| dnsmasq | the DNS caching server. Enable if your ISP or remote DNS caching server is pretty slow. | Enable |
| dkmdkms_autoinstallers | dkms is a framework which allows kernel modules to be dynamically built for each kernel on your system in a simplified and organized fashion. | Disable if possible |
| firstboot | RHLE specific service. It does a few configuration following successful installation of the operating system. | Disable |
| gpm | A cut and paste utility and mouse server service for virtual consoles. | Disable |
| haldaemon | This service is used for collecting and maintaing information about hardware from several sources. This is only used for X and desktop apps. Disable it on servers. | Disable |
| hplip | A service for non-PostScript HP printer. Disable it on servers. | Disable |
| irda | IrDA(TM) (Infrared Data Association) is an industry standard for wireless, infrared communication between devices. IrDA speeds range from 9600 bps to 4 Mbps, and IrDA can be used by many modern devices including laptops, LAN adapters, PDAs, printers, and mobile phones. | Disable if possible |
| iscsi & iscsid | iscsi service logs into iSCSI targets needed at system startup (i.e. iscsi client). iscsid will start and stop iSCSI daemon. Use this if you've iscsi based storage. | Disable if possible |
| iptables & ip6tables | IPv4 and IPv6 firewall service. | Enable and configure |
| irqbalance | The irqbalance service will distribute interrupts across the cpus on a multiprocessor system with the purpose of spreading the load. | Enable |
| isdn | Provides the Internet connectivity using an ISDN modem. | Disable if not using an ISDN modem. |
| kdump | Kernel crash dump analyzer. This service is useful for kernel hackers and device driver development or testing new kernel feature. Dsable the service on production boxes. | Disable |
| kudzu | RHEL specific hardware detection service. This is required on desktop or laptop where end users can add a new hardware but not on servers. | Disable |
| lm_sensors | lm_sensors is used for monitoring motherboard sensor values. | Disable |
| lvm2-monitor | Starts and stops dmeventd monitoring for lvm2. If you are not using LVM2 (Linux volume manager) based storage disable it. | Disable |
| mcstrans | Starts the SELinux Context Translation System daemon. This is site specific SELinux requirements. | Disable if possible |
| mdmonitor | software RAID monitoring and management service. If you are not using software RAID disable it. This is not required for hardware RAID setup as they comes with their own programs. | Disable if possible |
| messagebus | This service broadcasts notifications of system events and other messages (D-bus). Turn it on for bluetooth, X Windows and desktop systems. | Disable |
| microcode ctl | Script to apply cpu microcode for Intel IA32 processor. If you are not using Intel IA32 processor disable it. | Disable |
| netfs, nfslock, rpcgssd, rpcidmapd, and portmap | Mount and configure Linux network network filesystems (NFS). If you are not using NFS client/server technology disable it. | Disable if possible |
| network | A service to activates/deactivates all network interfaces configured to start at boot time. | Enable |
| pcscd | The PC/SC smart card sevice is a resource manager for the PC/SC lite and Musclecard frameworks. It coordinatescommunications with smart card readers, smart cards, and cryptographic tokens that are connected to the system.If Smart Cards are not in use on the system, disable this service: | Disable |
| readahead_early and readahead_later | This sevice provide one-time caching of files belonging to a few boot services. It does not provide any boosting. Just disable it. | Disable |
| restorecond | This service restores the correct security context for SELinux. | Enable |
| rhnsd | This service handles the task of connecting periodically to the RHN servers to check for updates, notifications and perform system monitoring tasks according to the service level that your server is subscribed for. Disable this service and use yum-updatesd service. | Disable |
| sendmail | Use to start sendmail server. | Enable and configure |
| smartd | Self Monitoring and Reporting Technology (SMART) Daemon for hard disks. | Enable and configure |
| setroubleshoot | This service starts the SELinux Troubleshooting daemon. It will send notification tothe desktop user of SELinux access denied messages in a user-friendly fashion. | Disable |
| sshd | The openssh server. If you need remote login enable it. You must enable this on all servers so that you can login and configure everything. | Enable |
| syslog | Syslog is the facility by which many other Linux daemons use to log messages to various system log files. It is a good idea to always run syslog. | Enable |
| xfs | X Windows font server. Disable it on servers. | Disable |
| yum-updatesd | Update notification daemon for system packages. | Enable |
| auditd | The audit package contains the user space utilities for storing and searching the audit records generate by the audit subsystem in the Linux 2.6 kernel. | * |
| cgconfig | Start cgconfigparser | |
| cgred | This is a daemon for automatically classifying processes into cgroups based on UID/GID | |
| cpuspeed | This program monitors the systemÂÂfs idle percentage and reduces or raises the CPUsÂÂf clock speeds and voltages accordingly to minimize power consumption when idle and maximize perfor-mance when needed. | |
| crond | The daemon to execute scheduled commands | * |
| ip6tables | It's IPv6 packet filter administration | |
| iptables | It's administration tool for IPv4 packet filtering and NAT | |
| lvm2-monitor | Monitor LVM2 with using dmeventd. | * |
| netconsole | It sends printk message from kernel on UDP. | |
| netfs | NFS client | |
| network | Network system | * |
| postfix | SMTP service daemon | |
| rdisc | Detect routers in local subnets | |
| restorecond | It's the daemon that watches for file creation and then sets the default SELinux file context. | |
| rsyslog | It reads and/or clears kernel message ring buffer; set console_loglevel. | * |
| saslauthd | saslauthd is a daemon process that handles plaintext authentication requests on behalf of the SASL library. | |
| sshd | OpenSSH SSH daemon. | * |
| udev-post | Moves the generated persistent udev rules to /etc/udev/rules.d. |
http://www.cyberciti.biz/faq/linux-default-services-which-are-enabled-at-boot/
http://www.server-world.info/en/note?os=CentOS_6&p=initial_conf&f=4
http://www.hao32.com/webserver/335.html