{"id":28386,"date":"2017-10-15T17:07:49","date_gmt":"2017-10-15T11:37:49","guid":{"rendered":"https:\/\/www.wikitechy.com\/technology\/?p=28386"},"modified":"2017-10-15T17:07:49","modified_gmt":"2017-10-15T11:37:49","slug":"program-remotely-power-pc-program-remotely-power-pc-internet-using-wake-lan-protocol-internet-using-wake-lan-protocol","status":"publish","type":"post","link":"https:\/\/www.wikitechy.com\/technology\/program-remotely-power-pc-program-remotely-power-pc-internet-using-wake-lan-protocol-internet-using-wake-lan-protocol\/","title":{"rendered":"Program to remotely Power On a PC over the internet using the Wake-on-LAN protocol."},"content":{"rendered":"<p>Wake-on-LAN (WoL) is an Ethernet or token ring computer networking standard that allows a computer to be turned on or awakened by a network message.<\/p>\n<ul>\n<li>The message is usually sent to the target computer by a program executed on a device connected to the same local area network, such as a smartphone.<\/li>\n<li>It is also possible to initiate the message from another network by using subnet directed broadcasts or a WOL gateway service.<\/li>\n<li>Equivalent terms include wake on WAN, remote wake-up, power on by LAN, power up by LAN, resume by LAN, resume on LAN and wake up on LAN.<\/li>\n<\/ul>\n<p><strong>Principle of operation<\/strong><\/p>\n<ul>\n<li>Wake-on-LAN (\u201cWOL\u201d) is implemented using a specially designed packet called a magic packet, which is sent to all computers in a network, among them the computer to be awakened.<\/li>\n<li>The magic packet contains the MAC address of the destination computer, an identifying number built into each network interface card (\u201cNIC\u201d) or other ethernet device in a computer, that enables it to be uniquely recognized and addressed on a network.<\/li>\n<li>Powered-down or turned off computers capable of Wake-on-LAN will contain network devices able to \u201clisten\u201d to incoming packets in low-power mode while the system is powered down.<\/li>\n<li>If a magic packet is received that is directed to the device\u2019s MAC address, the NIC signals the computer\u2019s power supply or motherboard to initiate system wake-up, much in the same way as pressing the power button would do.<\/li>\n<li>The magic packet is sent on the data link layer (layer 2 in the OSI model) and when sent, is broadcast to all attached devices on a given network, using the network broadcast address; the IP-address (layer 3 in the OSI model) is not used.[ad type=\u201dbanner\u201d]<\/li>\n<\/ul>\n<p>In order for Wake-on-LAN to work, parts of the network interface need to stay on. This consumes a small amount of standby power, much less than normal operating power. Disabling wake-on-LAN when not needed, can therefore very slightly reduce power consumption on computers that are switched off but still plugged into a power socket.<\/p>\n<p><strong>Magic Packet Structure<\/strong><br \/>\nThe magic packet is a broadcast frame containing anywhere within its payload 6 bytes of all 255 (FF FF FF FF FF FF in hexadecimal), followed by sixteen repetitions of the target computer\u2019s 48-bit MAC address, for a total of 102 bytes.<br \/>\nSince the magic packet is only scanned for the string above, and not actually parsed by a full protocol stack, it may be sent as any network- and transport-layer protocol, although it is typically sent as a UDP datagram to port 0, 7 or 9, or directly over Ethernet as EtherType 0x0842.<\/p>\n<p><strong>A standard magic packet has the following basic limitations:<\/strong><\/p>\n<ol>\n<li>Requires destination computer MAC address (also may require a SecureOn password).<\/li>\n<li>Does not provide a delivery confirmation.<\/li>\n<li>May not work outside of the local network.<\/li>\n<li>Requires hardware support of Wake-On-LAN on destination computer.<\/li>\n<li>Most 802.11 wireless interfaces do not maintain a link in low power states and cannot receive a magic packet.<\/li>\n<\/ol>\n<p>The Wake-on-LAN implementation is designed to be very simple and to be quickly processed by the circuitry present on the network interface card with minimal power requirement. Because Wake-on-LAN operates below the IP protocol layer the MAC address is required and makes IP addresses and DNS names meaningless.[ad type=\u201dbanner\u201d]\n<div>\u00a0C programming:<\/div>\n<div>\n[pastacode lang=\u201dc\u201d manual=\u201d%2F%2F%20C%20program%20to%20remotely%20Power%20On%20a%20PC%20over%20the%0A%2F%2F%20internet%20using%20the%20Wake-on-LAN%20protocol.%0A%23include%20%3Cstdio.h%3E%0A%23include%20%3Cstdlib.h%3E%0A%23include%20%3Cunistd.h%3E%0A%23include%20%3Csys%2Fsocket.h%3E%0A%23include%20%3Cnetinet%2Fin.h%3E%0A%23include%20%3Carpa%2Finet.h%3E%0A%23include%20%3Cstring.h%3E%0A%23include%20%3Csys%2Ftypes.h%3E%0A%20%0Aint%20main()%0A%7B%0A%20%20%20%20int%20i%3B%0A%20%20%20%20unsigned%20char%20toSend%5B102%5D%2Cmac%5B6%5D%3B%0A%20%20%20%20struct%20sockaddr_in%20udpClient%2C%20udpServer%3B%0A%20%20%20%20int%20broadcast%20%3D%201%20%3B%0A%20%0A%20%20%20%20%2F%2F%20UDP%20Socket%20creation%0A%20%20%20%20int%20udpSocket%20%3D%20socket(AF_INET%2C%20SOCK_DGRAM%2C%200)%3B%0A%20%0A%20%20%20%20%2F%2F%20Manipulating%20the%20Socket%0A%20%20%20%20if%20(setsockopt(udpSocket%2C%20SOL_SOCKET%2C%20SO_BROADCAST%2C%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%26broadcast%2C%20sizeof%20broadcast)%20%3D%3D%20-1)%0A%20%20%20%20%7B%0A%20%20%20%20%20%20%20%20perror(%22setsockopt%20(SO_BROADCAST)%22)%3B%0A%20%20%20%20%20%20%20%20exit(EXIT_FAILURE)%3B%0A%20%20%20%20%7D%0A%20%20%20%20udpClient.sin_family%20%3D%20AF_INET%3B%0A%20%20%20%20udpClient.sin_addr.s_addr%20%3D%20INADDR_ANY%3B%0A%20%20%20%20udpClient.sin_port%20%3D%200%3B%0A%20%0A%20%20%20%20%2F%2FBinding%20the%20socket%0A%20%20%20%20bind(udpSocket%2C%20(struct%20sockaddr*)%26udpClient%2C%20sizeof(udpClient))%3B%0A%20%0A%20%20%20%20for%20(i%3D0%3B%20i%3C6%3B%20i%2B%2B)%0A%20%20%20%20%20%20%20%20toSend%5Bi%5D%20%3D%200xFF%3B%0A%20%0A%20%20%20%20%2F%2F%20Let%20the%20MAC%20Address%20be%20ab%3Acd%3Aef%3Agh%3Aij%3Akl%0A%20%20%20%20mac%5B0%5D%20%3D%200xab%3B%20%20%2F%2F%201st%20octet%20of%20the%20MAC%20Address%0A%20%20%20%20mac%5B1%5D%20%3D%200xcd%3B%20%20%2F%2F%202nd%20octet%20of%20the%20MAC%20Address%0A%20%20%20%20mac%5B2%5D%20%3D%200xef%3B%20%20%2F%2F%203rd%20octet%20of%20the%20MAC%20Address%0A%20%20%20%20mac%5B3%5D%20%3D%200xgh%3B%20%20%2F%2F%204th%20octet%20of%20the%20MAC%20Address%0A%20%20%20%20mac%5B4%5D%20%3D%200xij%3B%20%20%2F%2F%205th%20octet%20of%20the%20MAC%20Address%0A%20%20%20%20mac%5B5%5D%20%3D%200xkl%3B%20%20%2F%2F%206th%20octet%20of%20the%20MAC%20Address%0A%20%0A%20%20%20%20for%20(i%3D1%3B%20i%3C%3D16%3B%20i%2B%2B)%0A%20%20%20%20%20%20%20%20memcpy(%26toSend%5Bi*6%5D%2C%20%26mac%2C%206*sizeof(unsigned%20char))%3B%0A%20%0A%20%20%20%20udpServer.sin_family%20%3D%20AF_INET%3B%0A%20%0A%20%20%20%20%2F%2F%20Braodcast%20address%0A%20%20%20%20udpServer.sin_addr.s_addr%20%3D%20inet_addr(%2210.89.255.255%22)%3B%0A%20%20%20%20udpServer.sin_port%20%3D%20htons(9)%3B%0A%20%0A%20%20%20%20sendto(udpSocket%2C%20%26toSend%2C%20sizeof(unsigned%20char)%20*%20102%2C%200%2C%0A%20%20%20%20%20%20%20%20%20%20%20%20%20(struct%20sockaddr*)%26udpServer%2C%20sizeof(udpServer))%3B%0A%20%20%20%20return%200%3B%0A%7D\u201d message=\u201d\u201d highlight=\u201d\u201d provider=\u201dmanual\u201d\/]\n<p>Output:<\/p>\n<pre>This program will power on the switched-off PC\r\nwhose MAC Address is used in this program (the \r\nPC and the Host computer must be connected over\r\nLAN).<\/pre>\n<\/div>\n[ad type=\u201dbanner\u201d]\n","protected":false},"excerpt":{"rendered":"<p>Program to remotely Power On a PC over the internet using the Wake-on &#8211; LAN protocol &#8211; Wake-on-LAN (WoL) is an Ethernet or or token ring computer networking<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[82277,71771],"tags":[82882,82880,82881,82884,82879,82883,82886,82885],"class_list":["post-28386","post","type-post","status-publish","format-standard","hentry","category-computer-networks","category-cs-subjects","tag-how-to-wake-on-lan","tag-wake-on-lan-command","tag-wake-on-lan-magic-packet","tag-wake-on-lan-online","tag-wake-on-lan-software","tag-wake-on-lan-windows","tag-wake-on-lan-windows-10","tag-wake-on-lan-windows-7"],"_links":{"self":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts\/28386","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/comments?post=28386"}],"version-history":[{"count":0,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts\/28386\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/media?parent=28386"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/categories?post=28386"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/tags?post=28386"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}