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Networking. SPARCS 2000 wheel seminar netj@sparcs.kaist.ac.kr. TCP/IP. Low-level networking software most commonly used with UNIX Internet Protocol Internet Control Message Protocol Address Resolution Protocol User Datagram Protocol. TCP/IP network model. Link layer
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Networking SPARCS 2000 wheel seminar netj@sparcs.kaist.ac.kr
TCP/IP • Low-level networking software most commonly used with UNIX • Internet Protocol • Internet Control Message Protocol • Address Resolution Protocol • User Datagram Protocol
TCP/IP network model • Link layer • Network hardware, device drivers • Network layer • Basic comm., addressing, routing • Transport layer • Comm. Among net programs • Application layer • Application programs
Addresses • Hardware address • IP Address • IP: xxx.xxx.xxx.xxx, 4bytes • Port: TCP/UDP, 2bytes • Internet address classes (A,B,C,D,E)
ARP • Address Resolution Protocol • Does address translation • IP Hardware Address • arp command • RARP, BOOTP
Routing • Process directing a packet through networks between its source and destination • RIP, OSPF, IGRP, EGP, BGP, DVMRP • ICMP redirects • CIDR (Classless Inter-Domain Routing) • route command • routed, gated
Network commands • ifconfig: configuring network interfaces • route: configure static routes • ping: check if a host is alive • netstat: network status • traceroute: trace IP packets • tcpdump, etherfind, snoop, arp
DNS • Domain Name System • Hostnames IP addresses • Distributed database that holds info about computers on the Internet • BIND, named
DNS defines, • Hierarchical namespace for hosts • Host table as a distributed database • Library routines for querying • Improved routing for email • Protocol for exchanging naming information
DNS Namespace • Top-level domains • COM, EDU, NET, ORG, GOV … • Country codes • KR, JP, CA, UK … • Root domain . • Subdomains • sparcs.kaist.ac.kr, www.kaist.ac.kr
DNS Architecture • IP Domain Name • Reversed query • 143.248.234.102 102.234.248.143.IN-ADDR.ARPA. sparcs.kaist.ac.kr • Domain Name IP • Querying sparcs.kaist.ac.kr. kr. ac.kr. kaist.ac.kr. sparcs.kaist.ac.kr.
NFS • Network File System • Share file systems among computers over network • mountd: mount responder • nfsd: serve files • biod: client-side caching • automount
NIS • Network Information Service • Sharing system files • rdist: push files • expect: pull files • yp commands • NIS+