How to connect to the Internet 1998/12/09 KEIO University, JAPAN Mikiyo

Overview of this section Internet connectable hardware/OS Why use the UNIX OS? Host connect to the network Server side configuring

Internet connectable hardware Hardwares –Workstation –PC (Personal Computer) –Set Top Box –Game machine and others –PDA

Internet connectable OS UNIX Family –FreeBSD –BSD/OS –Linux –SunOS Windows Family –Windows 95/98 –Windows NT

Why use the UNIX OS? The Internet was developed on UNIX UNIX’s TCP/IP stack, and service daemons are more reliable than Windows but, Windows can connecting network easy...Generally Front-end : Windows or UNIX Back-end : UNIX

Host connect to the network Configuring Network Interface Configuring Routing Table Configuring Name Resolver Automatic network configuration

Configuring Network Interface Network Interface has global unique IP Address Host is belong to a network - Network Interface has netmask

Setting IP Address and Netmask Use command “ifconfig” “ifconfig” command attach/detach/modify NIC’s network information –example: # ifconfig ed0 inet netmask

IP Address and Netmask IP Address is separated 2 parts –Host Address Indicate Host ID –Network Address Indicate Network ID host belong Netmask indicates Network Address part of IP Address

Special IP Address(1) Private IP Address –Not use for global Internet Localhost (indicate MYSELF)

Special IP Address(2) Datalink Broadcast Address –All nodes in the same network segment Network Address –Host Address part’s all bit are / netmask Network Broadcast Address –Host Address part’s all bit are / netmask

Configuring Routing Table For the communication, Host must send packet to router Routing Table is used where send the packet.

Setting Route in Routing table Command “route” set/unset/change route in routing table –example #route add #route add default

Routing Table Routing table has mapped data route (Destination Network - Next Hop Router) “default route” is route for unknown destination network Generally, End-node (Host) set “default route” to border router

Configuring Name Resolver TCP/IP Stack must resolve the matching hostname and IP Address For resolving, TCP/IP stack queries DNS Server

Name Resolver Setting Name Resolving DNS Server is describing “/etc/resolv.conf” If use statically hostname and IP Address table, describe “/etc/hosts”

Example of Name Resolver Setting /etc/resolv.conf DOMAIN sfc.wide.ad.jp NAMESEREVR SEARCH sfc.wide.ad.jp. wide.ad.jp. /etc/hosts myhost yourhost

Automatic Host Configuration DHCP - Dynamic Host Configuration Protocol –Automatically configure host setting IP Address Netmask DNS Server Address Default Route

Server side configuration DNS (bind) Entry Routing Daemon