1/14 Char 18 Sharing System Files Content –NIS(The Network Information Service) –NIS+

2/14 NIS Introduction NIS’s Old name : Sun Yellow Pages ==> yp prefix Support for NIS and NIS+ –Solaris - Partially, Yes –SunOS - Yes, No Server - content of shared files (maps) –ex) passwd.byname,passwd.byuid –group, networks, hosts, protocols, services aliases Server locating – IP broadcasting –ypset

3/14 Magic NIS Cookies Local priority - local machine’s info overrides NIS copy –/etc/passwd, /etc/group –Magic Cookies(‘+’) Global priority - NIS copy supersedes local copy –/etc/hosts, /etc/networks, /etc/protocols

4/14 Netgroups Abstraction of sets of user, machines, nets /etc/netgroup Format –groupname list-of-members –list-of-members : (hostname, username, domainname) –Blank, ‘-’ symbol –Example bobcats (snake,, ) (headrest,, ) servers (anchor,, ) (moet,, ) (piper,, ) (kirk,, ) allhosts beers serves

5/14 Netgroups(2) Usage Definition of permissions –/etc/exports –/etc/hosts.equiv or.rhosts in user’s Account info /etc/passwd

6/14 Technical Overview of NIS NIS directory –/var/yp, /usr/etc/yp, /etc/yp two ndbm file for each map –map.dir, map.pag –makedbm command ==> Makefile (run make in NIS dir) ypxfr, yppush command ypserv, ypbind daemon Figure P397,P398

7/14 Setting Up an NIS Domain Run ypinit on each server (page 398,399) On every machine(page 399) –set domain name from one of system startup files domainname command –import /etc/passwd, /etc/group

8/14 NIS+ Site-wide hierarchy More database-like Not use flat file as NIS does Incremental change and logging scheme Built on top of Sun’s secure RPC system

9/14 NIS+(2) From a client’s perspective, NIS+ looks much the same as any other administrative database system. Most data is accessed through the same library routines as always, and the complex world of domains, tables, permissions, and search paths is in the end rendered down to an analog of the original UNIX flat files

10/14 Char 21 Electronic Mail Content –Mail Systems –Aliases

11/14 Mail Systems Figure page 440 user agent (page 441,442) transport agent –SMTP(Simple Mail Transport Protocol) delivery agent –/bin/mail : local user –uux, spop : remote site user UUCP.POP(Post Office Protocol) Figure page 447

12/14 Spool Directory –/var/mail Mail Philosophy –A master mail server –A mail home for each user aliasing maildrop field of the user database

13/14 Mail Aliases Aliasing location –User agent’s config file –System-wide aliases file, /ect/aliases user’s forwarding file, ~/.forward –ex) ms1 : yskim, stoh, swkim... A file containing a list of addresses –ex) phd1 : :include:/user/phdlist

14/14 Mail Forwarding –~/.forward The Hashed Alias Database –/etc/aliases.dir - index –/etc/aliases.pag - real data –newaliases Mailing Lists –mylist : :include:/var/adm/aliases/mylist