666 gives access to internal services eg ability

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Unformatted text preview: ss Unrouted (private) IP addresses: Carnegie Mellon Internet Domain Names unnamed root .net mit cs ics greatwhite .edu cmu .gov berkeley ece .com amazon www First-level domain names Second-level domain names Third-level domain names 2007.171.166.252 sp i386-f7 Carnegie Mellon Domain Naming System (DNS) The Internet maintains a mapping between IP addresses and domain names in a huge worldwide distributed database called DNS Conceptually, programmers can view the DNS database as a collec2on of millions of host entry structures: */ official domain name of host */ null-terminated array of domain names */ host address type (AF_INET) */ length of an address, in bytes */ null-terminated array of in_addr structs /* DNS host entry structure struct hostent { char *h_name; /* char **h_aliases; /* int h_addrtype; /* int h_length; /* char **h_addr_list; /* */ }; Func8ons for retrieving host entries from DNS: gethostbyname: query key is a DNS domain name. gethostbyaddr: query key is an IP address. Carnegie Mellon Proper8es of DNS Host Entries Each host entry is an equivalence class of domain names and IP addresses Each host has a locally defined domain name localhost which always maps to the loopback address Different kinds of mappings are possible: Simple case: one-to-one mapping between domain name and IP address: greatwhile.ics.cs.cmu.edu maps to eecs.mit.edu and cs.mit.edu both map to 18.62....
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This note was uploaded on 04/06/2013 for the course ECE 18213 taught by Professor John during the Spring '13 term at Carnegie Mellon.

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