Introduction to Linux Services

The Linux service (Linux services) is important for every user who applies linux. Shutting down unwanted services can make Linux run more efficiently, but not all Linux services can be shut down. Today, I installed a CentOS Linux, and found out that Linux started a lot of services, and most of them didn't know what to do. So focus on the Linux services that can be shut down, and those Linux services (Linux service) cannot be shut down arbitrarily.

Before shutting down the Linux service, you need to know some concepts:

1. What is Linux service/background process (Linux services/daemons)
2. What is the Linux service RunLevel (Linux runlevels)
3. As well as a variety of tools for managing Linux service (Linux services).

Description of the Linux services (Linux Service) management tool:

1. You can use the Chkonfig or NTSYSV command at the command line to manage Linux services (Linux service)
2. Use the System-config-services command with a graphical user interface.
3. GNOME users can manage Linux services using->services server settings, System--

In general, the following Linux services are best not to shut down, they are system-level services because I am an entry-level Linux player, so I choose not to move them.

1. Acpid, Haldaemon, Messagebus, KLOGD, network, SYSLOGD

However, one of the most useful Linux services I use is sshd, which is necessary to connect to Linux via SSH. It is therefore seriously recommended to keep this. Also, is SendMail service, the author uses the CentOS Linux 5.2, actually installs the time by default installs the change service, because does not use, therefore closes. This service starts slow enough.
Finally, make sure that the modifications are run levels 3 and 5.

Linux Service (Linux services):NetworkManager, Networkmanagerdispatcher
NetworkManager is a background process that automatically switches network connections. Many notebook users need to enable this feature, which allows you to switch between a wireless network and a wired network. Most desktop users should close the service. Some DHCP users may need to open it.
Linux Service (Linux services):acpid
The ACPI (full name Advanced Configuration and Power Interface) service is the power management interface. It is recommended that all notebook users open it. Some servers may not require ACPI. Common operations supported are: "Power switch", "Battery Monitor", "notebook Lid Switch", "Notebook display Brightness", "hibernate", "Hang Up", and so on.

Linux Service (Linux services):Anacron, ATD, Cron
There is a small difference between these schedulers. It is recommended that you turn on cron, and if your computer will run for a long time, you should turn it on. For servers, you should take a closer look to determine which scheduler should be turned on. In most cases, laptops/desktops should turn off ATD and Anacron. Note: The execution of some tasks requires anacron, such as: clean///var.

Linux Service (Linux services):APMD
Some notebooks and old hardware use APMD. If your computer supports ACPI, you should turn off APMD. If ACPI is supported, then APMD's work will be done by ACPI.

Linux Service (Linux services):autofs
The service automatically mounts Removable Storage (such as a USB drive). If you use mobile media (such as a removable hard disk, USB flash drive), it is recommended to enable this service.

Linux Service (Linux services):Avahi-daemon, AVAHI-DNSCONFD
Avahi is the implementation of the ZEROCONF protocol. It can discover devices and services based on the ZEROCONF protocol in a LAN that does not have a DNS service. It's just like MDNS. Unless you have a compatible device or a service that uses the ZEROCONF protocol, you should turn it off.

Linux Service (Linux services):Bluetooth, Hcid, Hidd, SDPD, Dund, Pand
Bluetooth is used for wireless portable devices (non-wifi, 802.11). Many laptops offer Bluetooth support. There are Bluetooth mice, Bluetooth headsets and Bluetooth-enabled phones. Many people don't have Bluetooth devices or Bluetooth-related services, so it should be turned off. Other Bluetooth related services are: Hcid to manage all the visible Bluetooth devices, Hidd support for Input devices (keyboard, mouse), Dund support via Bluetooth dial-up connection network, Pand allows you to connect to Ethernet via Bluetooth.

Linux Service (Linux services):CAPI
is only useful for users who use ISDN devices. Most users should close it.

Linux Service (Linux services):cpuspeed
The service can dynamically adjust the frequency of the CPU at run time to conserve energy (power saving). Many notebook CPUs support this feature, and now more and more desktops are supporting this feature. If your CPU is: Petium-m,centrino,amd powernow, Transmetta,intel speedstep,athlon-64,athlon-x2,intel Core 2, you should turn it on. If you want your CPU to run at a fixed frequency, turn it off.

Linux Service (Linux services):cron
See Anacron.

Linux Service (Linux services):cupsd, Cups-config-daemon
Printer-related. If you have a CUPS-compatible printer that you can drive in Fedora, you should turn it on.

Linux Service (Linux services):dc_client, Dc_server
The disk cache (Distcache) is used for distributed session caching. Mainly used in SSL/TLS servers. It can be used by Apache. Most desktops should turn it off.

Linux Service (Linux services):dhcdbd
This is an interface that allows the DBUS system to control DHCP. You can leave the default shutdown state.

Linux Service (Linux services):diskdump, Netdump
Disk dumps (Diskdump) are used to help debug kernel crashes. After the kernel crashes it will save a "dump" file for analysis. The network dump (netdump) function is similar to diskdump, except that it can be stored over the network. Unless you are diagnosing kernel-related problems, they should be shut down.

Linux Service (Linux services):dund
See bluetooth.

Linux Service (Linux services):firstboot
This service is unique to the Fedora installation process. It performs a specific task that only needs to be performed once at the first boot after installation. It can be turned off.

Linux Service (Linux services):gpm
Terminal mouse pointer support (no graphical interface). If you do not use a text terminal (CTRL-ALT-F1, F2. ), then close it. However, I turned it on at run Level 3 and closed it at run Level 5.

Linux Service (Linux services):Hidd
See bluetooth.

Linux Service (Linux services):Hplip, Hpiod, HPSSD
The Hplip service implements HP printer support on Linux systems, including Inkjet,deskjet,officejet,photosmart,business Inkjet and part LaserJet printers. This is the product of HP-sponsored HP Linux print projects (HP Linux Printing project). If you have a compatible printer, enable it.

Linux Service (Linux services):iptables
It is the Linux standard firewall (software firewall). If you are connected directly to the Internet (e.g., cable,dsl,t1), it is recommended to turn it on. If you use a hardware firewall (for example: D-link,netgear,linksys, etc.), you can turn it off. It is highly recommended to open it.

Linux Service (Linux services):ip6tables
If you do not know if you are using IPV6, in most cases you are not using it. The service is a software firewall for IPV6. Most users should close it. Read here to learn how to turn off Fedora's IPv6 support.

Linux Service (Linux services):IrDA, Irattach
IrDA provides communication support between infrared devices (notebooks, PDAs ' s, mobile phones, calculators, etc.). Most users should close it.

Linux Service (Linux services):irqbalance
In a multiprocessor system, enabling the service can improve system performance. Most people don't use multiprocessor systems, so turn it off. But I don't know how it works on multicore CPUs ' s or Hyper-threading CPUs ' s systems. It should not be a problem to shut down in a single CPU system.

Linux Service (Linux services):ISDN
This is an Internet access method. Unless you use an ISDN cat to surf the internet, you should turn it off.

Linux Service (Linux services):kudzu
The service is hardware-probed and configured. If you replace the hardware or need to detect hardware changes, turn it on. But most desktops and servers can shut it down and start only when needed.

Linux Service (Linux services):lm_sensors
The service can detect the value of the motherboard sensing device or the state of a particular hardware (typically used in a laptop computer). You can check the status of your computer in real-time and learn about your computer's health. It is more popular among GKRELLM users. See Lm_sensors's homepage for more information. If there is no special reason, it is advisable to close it.

Linux Service (Linux services):Mctrans
If you use SELinux, turn it on. By default, CentOS and Fedora Core turn on SELinux.

Linux Service (Linux services):mdmonitor
This service is used to monitor software RAID or LVM information. It is not a critical service and can be shut down.

Linux Service (Linux services):mdmpd
This service is used to monitor multi-path devices (this type of storage device can be accessed by more than one controller or method). It should be closed.

Linux Service (Linux services):Messagebus
This is the IPC (interprocess communication, interprocess communication) service for Linux. To be exact, it interacts with DBUS and is an important system service. It is highly recommended to open it.

Linux Service (Linux services):netdump
See diskdump.

Linux Service (Linux services):netplugd
The NETPLUGD is used to monitor the network interface and execute the specified command when the interface state changes. It is recommended to keep its default shutdown state.

Linux Service (Linux services):netfs
This service is used to automatically mount the shared file space on the network when the system is started, such as: Nfs,samba, and so on. If you connect to another server on the LAN and file sharing, open it. Most desktop and notebook users should turn it off.

Linux Service (Linux services):NFS, Nfslock
This is the standard file sharing method for the UNIX/LINUX/BSD series operating system. Unless you need to share the data in this way, close it.

Linux Service (Linux services):ntpd
The service automatically updates the system time over the Internet. If you can permanently maintain an Internet connection, it is recommended to open it, but not necessary.

Linux Service (Linux services):pand
See bluetooth.

Linux Service (Linux services):PCSCD
The service provides smart cards (and is embedded in a credit card, the same size as the small chip of the identification cards) and smart card reader support. If you don't have a reader device, turn it off.

Linux Service (Linux services):Portmap
This service is a complement to NFS (file sharing) and NIS (authentication). Unless you are using NFS or NIS services, turn it off.

Linux Service (Linux services): Readahead_early, Readahead_later
The service provides performance by preloading specific applications into memory. If you want the program to start faster, turn it on.

Linux Service (Linux services):Restorecond
Used to monitor and reload the correct file context (filename contexts) for SELinux. It is not required, but if you use SELinux it is strongly recommended to turn it on.

Linux Service (Linux services):RPCGSSD, RPCIDMAPD, RPCSVCGSSD
For NFS V4. Unless you need or use NFS v4, turn it off.

Linux Service (Linux services):sendmail
Unless you are managing a mail server or you want to deliver or support a shared IMAP or POP3 service within a LAN. Most people don't need a mail transfer agent. If you send and receive programs via the Web (hotmail/yahoo/gmail) or by using the mail transceiver (e.g., thunderbird,kmail,evolution, etc.). You should close it. (the author in the use of CentOS 5.2, incredibly automatically installed this service, close it)

Linux Service (Linux services):SMARTD
The Smart Disk monitoring service is used to monitor and predict disk failures or disk problems (provided that the disks must support SMART). Most desktop users do not need the service, but it is recommended to turn it on, especially the server.

Linux Service (Linux services):SMB
SAMBA services are the services that are required to share files between Linux and Windows. If a Windows user needs access to a file on Linux, enable it.

Linux Service (Linux services):sshd
SSH allows other users to log on to your system and execute the program, which can be the same network as you, or a remote user. There are potential security implications for opening it. If you do not need to be from another machine or do not need to log on remotely, you should close it. The author strongly recommends that the service be retained, or that it is not possible to use the SSHD service if Linux is used.

Linux Service (Linux services):xinetd
(The service may not be installed by default) it is a special service. It can start multiple services based on requests received from a particular port. For example: A typical Telnet program is connected to Port 23rd. If a telent request is detected by xinetd on Port 23rd, the XINETD will initiate the TELNETD service to respond to the request. For ease of use, you can turn it on. Run chkconfig–list to know which services are xinetd managed by checking the xinetd related output.

Introduction to Linux Services