Summer 2009Daemons: Printing+ Printingó lpd – the “standard” BSD print spooling daemon.à Accepts jobs, places them in a spoolCNT 4603Summer 2009Daemons: Printingà If lpd is operating locally, then it does theinteraction with printer (these days, almost alwaysvia a filter that does the actual communication)à If not local, then (unsurprisingly) the daemon sendsthe job to another machine; the lpd protocol (RFC1179, see http://www.ietf.org/rfc/rfc1179.txt) wasnot a great design successCNT 4603Summer 2009Daemons: Printingó lpsched – the “standard” ATT version of lpd ; itis more complex to administer (see Chapter 23 ofUSAH) and, while it was less likely to wander off thereservation once it is in operation, configuration canbe much more interesting and problem-laden than lpd.lpsched uses the same RFC 1179 protocol, which itinherited from BSD.CNT 4603Summer 2009Daemons: Printingó lprng – an open source lpd replacement, includesa “Printing Cookbook” for people who like details.However, lprng doesn’t seem to be gaining popularity;cups instead seems to have overtaken itCNT 4603Summer 2009Daemons: Printingó cups – a very popular open source replacementwhich disposes of the problematic RFC 1179 protocol,replacing it with IPP (RFC2567 (good explanation ofthe overall view of the protocol’s design), RFC2568,RFC2569, RFC2639, RFC2910, RFC2911, RFC3196,RFC3239, RFC3380, RFC3381, RFC3382, RFC3391,RFC3510, RFC3712, RFC3995, RFC3996, RFC3997,RFC3998)CNT 4603Summer 2009Daemons: Printingó Windows 2008 – You can use the Server Managerapplication to turn on the printing “feature”.CNT 4603Summer 2009Windows 2008CNT 4603Summer 2009Windows 2008CNT 4603Summer 2009Windows 2008CNT 4603Summer 2009Windows 2008CNT 4603Summer 2009Windows 2008CNT 4603Summer 2009Daemons: MTAs/MSAs+ Mail Transfer Agents (MTAs, see for instanceRFC2821) and Mail Submission Agents (MSAs,RFC2476)CNT 4603Summer 2009Daemons: MTAs/MSAs+ sendmail+ Routes local and network mail. Acts as MTA (and asan MSA listening on port 587), sendmail is one of theInternet email backbone workhorse programs.CNT 4603Summer 2009Daemons: MTAs/MSAs+ One of the larger and certainly historically “buggiest”daemons, although the latest versions have securitypatches developed as needed (it is always a good ideato check http://www.sendmail.org for the latest onsendmail security.)+ Configuration information is kept these days in thesubdirectory /etc/mail.CNT 4603Summer 2009Daemons: MTAs/MSAs+ The file /etc/mail/sendmail.cf is a set of rewritingrules for modifying addresses; luckily tools exist toautomate creation of this file (basically, you use a“makefile” that rewrites a “.mc” file into a “.cf”file. Check http://www.sendmail.org/ for lots moreinformation – the op.ps manual is the canonicalreading material, although the O’Reilly book is easier.Unfortunately, some distributions have bizarrely takenCNT 4603Summer 2009this makefile and turned into a simple invocation to avery complex shell script.)CNT 4603Summer 2009Daemons: MTAs/MSAs+ sendmail is covered in LAH, plus there is an entireO’Reilly & Associates book is dedicated to sendmail .CNT 4603Summer 2009Daemons: MTAs/MSAs+ Current, sendmail 8.14 is quite popular as an MTA.The ability to use a bolt-on “milter” (mail filter) wasadded (see http://www.milter.org), and now sendmailis probably the most flexible MTA when dealing withworking at a message level; milters can detect and rejectspam, they can check for legitimate users even for justforwarding MTAs, they can be implemented in C, C++,Perl, and Python.CNT 4603Summer 2009Daemons: MTAs/MSAs+ postfix+ postfix comes from IBM, and has become probably thesecond most popular MTA. (http://www.postfix.org)+ It is very powerful: and postfix now does handlemilters. It does have a large set of configuration filesthat work very well together.CNT 4603Summer 2009+ The configuration is typically in /etc/postfix.CNT 4603Summer 2009Daemons: Other MTAs/MSAs+ qmail - Dan Bernstein’s MTA (http://www.qmail.org).+ smail - an older, less popular MTA from GNU; however,it has been very stable+ exim - an MTA from Cambridge, gaining in popularity,now found in many Linux distributions such as RedHat(CentOS) and Debian (where it is now the default MTA)CNT 4603Summer 2009+ Exchange - the enterprise Windows email server fromMicrosoftCNT 4603Summer 2009Daemons: MTAs/MSAs+ SA relevance:+ Mail service is the most popular and, arguably, mostimportant service on your system (along with webservice)+ Users get upset when mail does not work+ As with any other network service, you must keep upwith the latest security patchesCNT 4603Summer 2009Daemons: MTAs/MSAs+ Configuring and tuning sendmail can take a lot ofSA time, although generally using the m4 files allowdeployment with just a little bit of effort — for a GUIapproach, look at webmin at http://www.webmin.com,for instanceCNT 4603Summer 2009Daemons: MTAs/MSAs+ Very important these days in both server and clientsupport is anti-spam and anti-virus protection. From aserver perspective, the biggest tools are+ MailScanner (http://www.mailscanner.info) (serveronly)+ clamav (http://www.clamav.net) (runs on both clientand server)CNT 4603Summer 2009+ razor (http://razor.sourceforge.net) (generally invokedwithin SpamAssassin)+ dcc (http://www.dcc-servers.net/dcc) (generallyinvoked within SpamAssassin)+ SpamAssassin (http://spamassassin.apache.org/) (generallyrun on servers)+ Realtime Blackhole List (RBL) source, (for instance,http://www.spamhaus.org) (most powerful when usedat the initial MTA contact, although SpamAssassin canCNT 4603Summer 2009consult RBLs and we have used it both ways in thedepartment)CNT 4603Summer 2009NFS - Network File Service+ NFS was developed by Sun and is now used by manyUNIX/Linux systems+ It allows file access across the network as if the fileswere localCNT 4603Summer 2009NFS - Network File Service+ NFS exists as a number of daemons - nfsd, biod, etc.,as well as in kernel file system code+ NFS is covered in Ch. 17 of USAH and we will coverit in more detail in a later lectureCNT 4603Summer 2009Yellow pages (NIS and NIS+)+ Now deprecated even by Sun in favor of LDAP+ Allows key system files (“maps”) to be shared overthe net using a UNIX/Linux dbm database and aclient/server model running on top of RPC.1. ‘‘ypcat passwd | more’’ *vs*2. ‘‘more /etc/passwd’’3. /var/yp on the YP server and clientsCNT 4603Summer 20094. YP == NIS (Network Information