HTTP ProtocolsRequest: GETRespond: OK 200 / 400 Bad Req. / 404 Not FoundSSDP: Simple Service Discovery Protocol (SSDP)SSDP: Search and NotifyUsing CacheSlide Number 7Showing Large MessageAuthenticationDecoding the Base64HTTP ProtocolsWireshark LabRequest: GETMyComputer ServerRespond: OK 200 / 400 Bad Req. / 404 Not FoundServerPage 57 of TextMyComputerText/html or image/jpegSSDP: Simple Service Discovery Protocol (SSDP)• SSDP is a text-based protocol based on the Hypertext Transfer Protocol– SSDP uses UDP transport protocol on port 1900– multicast adress (239.255.255.250)• This protocol allows you to discover and configure devices using uPnP(Universal Plug and Play) automatically, this process is referred to as SSDP Discover– No need for Dynamic Host Configuration Protocol (DHCP) or the Domain Name System (DNS) – name server is available – supported by Microsoft Windows operating systems– Allows automatically joining a network without having DHCP (useful for wireless)• A client that wishes to discover available services on a network, uses the M-SEARCH method– Responses to such search requests are sent via unicast addressing to the originating address and port number of the multicast request• such search requests are sent via unicast addressing to the originating address and port number of the multicast requestUse the following to eliminate showing these messages: not udp.dstport == 1900SSDP: Search and Notifyhttp://www.mudynamics.com/resources/collaterals/SSDP-ProtocolBrief.pdfUsing Cache• Before the request it check the browser checks the cache• If it is there checks to see if there is any change in the file using IF-MODIFIED-SINCE• If the file is not modified then NO MODIFIED response will be returnedFirst HTTP GET Second HTTP GETShowing Large MessageAuthentication• Base64 (2^6)• Consider an example: Man• The buffer is 24-bit wide – then we take 6 bit at a timeASCIIDecoding the