unix unleashed system administrators edition phần 9 ppt

handle. Regardless of the complexity of the address, ruleset 3's job is to decide the next host to which a letter should be sent. Ruleset 3 tries to locate that host in the address and mark it within angle brackets. In the simplest case, an address like joe@gonzo.gov becomes joe<@gonzo.gov>. Ruleset 0 then determines the correct delivery agent (mailer) to use for each recipient. For instance, a letter from betty@whizzer.com to joe@gonzo.gov (an Internet site) and pinhead!zippy (an old-style UUCP site) will require two different mailers: an SMTP mailer for gonzo.gov and an old-style UUCP mailer for pinhead. Mailer selection determines later processing of sender and recipient addresses because the rulesets given in the S= and R= mailer flags vary from mailer to mailer. Addresses sent through ruleset 0 must resolve to a mailer. This means that when an address matches the lhs, the rhs gives a triple 2 of mailer, user, host. The following line shows the syntax for a rule that resolves to a mailer: Rlhs $#mailer $@host $:user your comment here The mailer is the name of one of the mailers you've defined in an M command, for instance smtp. The host and user are usually positional macros taken from the lhs match. (See "The Righthand Side (rhs) of Rules," later in the chapter.) After sendmail selects a mailer in ruleset 0, it processes sender addresses through ruleset 1 (often empty), and then sends them to the ruleset given in the S= flag for that mailer. Similarly, it sends recipient addresses through ruleset 2 (also often empty), and then to the ruleset mentioned in the R= mailer flag. Finally, sendmail post-processes all addresses in ruleset 4, which among other things removes the angle brackets inserted by ruleset 3. Why do mailers have different S= and R= flags? Consider the example above of the letter sent to joe@gonzo.gov and pinhead!zippy. If betty@whizzer.com sends the mail, her address must appear in a different form to each recipient. For Joe, it should be a domain address, betty@whizzer.com. For Zippy, since whizzer.com expects old-style UUCP addresses (and assuming it has a UUCP link to pinhead and whizzer.com's UUCP hostname is whizzer), the return address should be whizzer!betty. Joe's address must also be rewritten for the pinhead UUCP mailer, and Joe's copy must include an address for Zippy that his mailer can handle. Processing Rules Within Rulesets sendmail passes an address to a ruleset, and then processes it through each rule line by line. If the lhs of a rule matches the address, it is rewritten by the rhs. If it doesn't match, sendmail continues to the next rule until it reaches the end of the ruleset 3 . At the end of the ruleset, sendmail returns the rewritten address to the calling ruleset or to the next ruleset in its built-in execution sequence. If an address matches the lhs and is rewritten by the rhs, the rule is tried again an implicit loop (but see the $@ and $: modifiers below for exceptions). As shown in Table 24.1, each rewriting rule is introduced by the R command and has three fields, the left-hand side (lhs, or matching side), the righthand side (rhs, or rewriting side) and an optional comment, each of which must be separated by tab characters: Rlhs rhs comment Parsing Turning Addresses into Tokens sendmail parses addresses and the lhs of rules into tokens and then matches the address and the lhs, token by token. The macro $o contains the characters that sendmail uses to separate an address into tokens. It's often defined like this: # address delimiter characters Do.:%@!^/[] All of the characters in $o are both token separators and tokens. sendmail takes an address such as rae@rainbow.org and breaks it into tokens according to the characters in the o macro, like this: "rae" "@" "rainbow" "." "org" sendmail also parses the lhs of rewriting rules into tokens so they can be compared one by one with the input address to see if they match. For instance, the lhs $-@rainbow.org gets parsed as: "$-" "@" "rainbow" "." "org" (Don't worry about the $- just yet. It's a pattern-matching operator similar to shell wild cards that matches any single token, and is covered below in "The Left-hand Side (lhs) of Rules.") Now we can put the two together to show how sendmail decides whether an address matches the lhs of a rule: "rae" "@" "rainbow" "." "org" "$-" "@" "rainbow" "." "org" In this case, each token from the address matches a constant string (e.g., rainbow) or a pattern-matching operator ($-), so the address matches and sendmail would use the rhs to rewrite the address. Consider the effect (usually bad!) of changing the value of $o. As shown above, sendmail breaks the address rae@rainbow.org into five tokens. However, if the @ character were not in $o, the address would be parsed quite differently, into only three tokens: "rae@rainbow" "." "org" You can see that changing $o has a drastic effect on sendmail's address parsing, and you should leave it alone until you really know what you're doing. Even then you probably won't want to change it since the V8 sendmail configuration files already have it correctly defined for standard RFC 822 and RFC 976 address interpretation. The Left-hand Side (lhs) of Rules The lhs is a pattern against which sendmail matches the input address. The lhs may contain ordinary text or any of the pattern-matching operators shown in Table 24.2: Table 24.2. lhs pattern-matching operators. $- Match exactly one token 4 $+ Match one or more tokens $* Match zero or more tokens $@ Match the null input (used to call the error mailer) The values of macros and classes are matched in the lhs with the operators shown in Table 24.3: Table 24.3. lhs macro and class matching operators. $X Match the value of macro X $=C Match any word in class C $~C Match if token is not in class C The pattern-matching operators and macro- and class-matching operators are necessary because most rules must match many different input addresses. For instance, a rule might need to match all addresses that end with gonzo.gov and begin with one or more of anything. The Right-hand Side (rhs) of Rules The rhs of a rewriting rule tells sendmail how to rewrite an address that matches the lhs. The rhs may include text, macros, and positional references to matches in the lhs. When a pattern-matching operator from Table 24.2 matches the input, sendmail assigns it to a numeric macro $n, corresponding to the position it matches in the lhs. For instance, suppose the address joe@pc1.gonzo.gov is passed to the following rule: R$+ @ $+ $: $1 < @ $2 > focus on domain In this example, joe matches $+ (one or more of anything), so sendmail assigns the string joe to $1. The @ in the address matches the @ in the lhs, but constant strings are not assigned to positional macros. The tokens in the string pc1.gonzo.gov match the second $+ and are assigned to $2. The address is rewritten as $1<@$2>, or joe<@pc1.gonzo.gov>. $: and $@ Altering a Ruleset's Evaluation Consider the following rule: R$* $: $1 < @ $j > add local domain After rewriting an address in the rhs, sendmail tries to match the rewritten address with the lhs of the current rule. Since $* matches zero or more of anything, what prevents sendmail from going into an infinite loop on this rule? After all, no matter how the rhs rewrites the address, it will always match $*. The $: preface to the rhs comes to the rescue; it tells sendmail to evaluate the rule only once. There are also times when you want a ruleset to terminate immediately and return the address to the calling ruleset or the next ruleset in sendmail's built-in sequence. Prefacing a rule's rhs with $@ causes sendmail to exit the ruleset immediately after rewriting the address in the rhs. $> Calling Another Ruleset A ruleset can pass an address to another ruleset by using the $> preface to the rhs. Consider the following rule: R$* $: $>66 $1 call ruleset 66 The lhs $* matches zero or more of anything, so sendmail always does the rhs. As we saw in the previous section, the $: prevents the rule from being evaluated more than once. The $>66 $1 calls ruleset 66 with $1 as its input address. Since the $1 matches whatever was in the lhs, this rule simply passes the entirety of the current input address to ruleset 66. Whatever ruleset 66 returns is passed to the next rule in the ruleset. Testing Rules and Rulesets the -bt, -d and -C Options Debugging a sendmail.cf can be a tricky business. Fortunately, sendmail provides several ways to test rulesets before you install them. NOTE: The examples in this section assume that you have a working sendmail. If your system doesn't, try running them again after you've installed V8 sendmail. The -bt option tells sendmail to enter its rule-testing mode: $ sendmail -bt ADDRESS TEST MODE (ruleset 3 NOT automatically invoked) Enter <ruleset> <address> > NOTE: Notice the warning ruleset 3 NOT automatically invoked. Older versions of sendmail ran ruleset 3 automatically when in address test mode, which made sense since sendmail sends all addresses through ruleset 3 anyway. V8 sendmail does not, but it's a good idea to invoke ruleset 3 manually since later rulesets expect the address to be in canonical form. The > prompt means sendmail is waiting for you to enter one or more ruleset numbers, separated by commas, and an address. Try your login name with rulesets 3 and 0. The result should look something like this: > 3,0 joe rewrite: ruleset 3 input: joe rewrite: ruleset 3 returns: joe rewrite: ruleset 0 input: joe rewrite: ruleset 3 input: joe rewrite: ruleset 3 returns: joe rewrite: ruleset 6 input: joe rewrite: ruleset 6 returns: joe rewrite: ruleset 0 returns: $# local $: joe > The output shows how sendmail processes the input address joe in each ruleset. Each line of output is identified with the number of the ruleset processing it, the input address, and the address that the ruleset returns. The > is a second prompt indicating that sendmail is waiting for another line of input. When you're done testing, just type Ctrl+D. Indentation and blank lines better show the flow of processing in this example: rewrite: ruleset 3 input: joe rewrite: ruleset 3 returns: joe rewrite: ruleset 0 input: joe rewrite: ruleset 3 input: joe rewrite: ruleset 3 returns: joe rewrite: ruleset 6 input: joe rewrite: ruleset 6 returns: joe rewrite: ruleset 0 returns: $# local $: joe The rulesets called were 3 and 0, in that order. Ruleset 3 was processed and returned the value joe, and then sendmail called ruleset 0. Ruleset 0 called ruleset 3 again, and then ruleset 6, an example of how a ruleset can call another one by using $>. Neither ruleset 3 nor ruleset 6 rewrote the input address. Finally, ruleset 0 resolved to a mailer, as it must. Often you need more detail than -bt provides usually just before you tear out a large handful of hair because you don't understand why an address doesn't match the lhs of a rule. You may remain hirsute because sendmail has verbose debugging built-in to most of its code. You use the -d option to turn on sendmail's verbose debugging. This option is followed by a numeric code that tells which section of debugging code to turn on, and at what level. The following example shows how to run sendmail in one of its debugging modes and the output it produces: $ sendmail -bt -d21.12 Version 8.6.7 ADDRESS TEST MODE (ruleset 3 NOT automatically invoked) Enter <ruleset> <address> > 3,0 joe rewrite: ruleset 3 input: joe trying rule: $* < > $* rule fails trying rule: $* < $* < $* < $+ > $* > $* > $* rule fails [etc.] The -d21.12 in the example above tells sendmail to turn on level 12 debugging in section 21 of its code. The same command with the option -d21.36 gives more verbose output (debug level 36 instead of 12). NOTE: You can combine one or more debugging specifications separated by commas, as in -d21.12,14.2, which turns on level 12 debugging in section 21 and level 2 debugging in section 14. You can also give a range of debugging sections, as in -d1-10.35, which turns on debugging in sections 1 through 10 at level 35. The specification -d0-91.104 turns on all sections of V8 sendmail's debugging code at the highest levels and produces thousands of lines of output for a single address. The -d option is not limited to use with sendmail's address testing mode (-bt); you can also use it to see how sendmail processes rulesets while sending a letter, as the following example shows: $ sendmail -d21.36 joe@gonzo.gov < /tmp/letter [lots and lots of output ] Unfortunately, the SIOG doesn't tell you which numbers correspond to which sections of code. Instead, the author suggests that it's a lot of work to keep such documentation current (which it is), and that you should look at the code itself to discover the correct debugging formulas. The function tTd() is the one to look for. For example, suppose you wanted to turn on debugging in sendmail's address-parsing code. The source file parseaddr.c contains most of this code, and the following command finds the allowable debugging levels: $ egrep tTd parseaddr.c if (tTd(20, 1)) [ ] if (tTd(24, 4)) if (tTd(22, 11)) [etc.] The egrep output shows that debugging specifications like -d20.1, -d24.4, and -d22.11 (and others) will make sense to sendmail. If perusing thousands of lines of C code doesn't appeal to you, the book sendmail documents the debugging flags for sendmail version 8.6.9. The -C option allows you to test new configuration files before you install them, which is always a good idea. If you want to test a different file, use -C/path/to/the/file. This can be combined with the -bt and -d flags. For instance, a common invocation for testing new configuration files is: sendmail -Ctest.cf -bt -d21.12 WARNING: For security, sendmail drops its super-user permissions when you use the -C option. Final testing of configuration files should be done as the super-user to ensure that your testing is compatible with sendmail's normal operating mode. Conclusion Now you know a lot about the sendmail.cf language as well as some useful debugging techniques. However, configuration files will be easier to grasp when you look at some real ones. The section below shows you how to create one from the m4 templates included with V8 sendmail. Creating a sendmail.cf In this section, we'll develop a sendmail.cf for a Solaris 2.3 system, using the templates supplied with V8 sendmail. However, because every site is different, even if you're developing a sendmail.cf for another Solaris 2.3 system, yours will probably differ from the one below. Previous versions of sendmail included complete, sample configuration files to adapt for your site. By contrast, the V8 sendmail configuration files are supplied as m4 templates that you use like building blocks to create a custom configuration file. This is a big advantage for most people. In previous versions, if your site did not want UUCP support, you had to pick through hundreds of lines of a configuration file and remove it line by line. In this version, you simply insert the statement FEATURE(nouucp) into your configuration file template and you are done. M4 is a programming language that reads a file of macro definitions and commands and creates an output file from it. As a trivial example, suppose you create a document and find yourself repeatedly typing the phrase sendmail Installation and Operation Guide. To avoid the extra typing, you could define a macro siog and enter that instead: $ cat > test.m4 define('siog','Sendmail Installation and Operation Guide')dnl Testing: siog Ctrl+D $ m4 test.m4 Testing: Sendmail Installation and Operation Guide Running m4 on the file test.m4 converts all occurrences of siog to sendmail Installation and Operation Guide. This example only hints at m4's capabilities. The V8 sendmail.cf templates make full use of them. The sendmail.cf templates and m4 support files are in the cf directory you created earlier when you unpacked V8 sendmail: $ cd cf $ ls -CF README domain/ hack/ mailer/ sh/ cf/ feature/ m4/ ostype/ siteconfig/ Please note the file README. If you don't read it, you have little hope of making a working configuration file. The cf subdirectory is the main one of interest. It contains m4 templates for configuration files used at the University of California at Berkeley (UCB). You should look at them all; one of them may be very close to what you need, and all of them provide good examples for you to adapt to your own site. The other subdirectories contain m4 support files, the building blocks that are included based on the template you define in the cf subdirectory. You probably won't have to change any of these, although you may need to create site-specific files in the domain and siteconfig subdirectories. The cf subdirectory contains the following configuration file templates: $ cd cf $ ls -CF Makefile knecht.mc sunos4.1-cs-exposed.mc Makefile.dist mail.cs.mc sunos4.1-cs-hidden.mc alpha.mc mail.eecs.mc tcpproto.mc auspex.mc obj/ ucbarpa.mc chez.mc osf1-cs-exposed.mc ucbvax.mc clientproto.mc osf1-cs-hidden.mc udb.mc cogsci.mc python.mc ultrix4.1-cs-exposed.mc cs-exposed.mc riscos-cs-exposed.mc ultrix4.1-cs-hidden.mc cs-hidden.mc s2k.mc uucpproto.mc hpux-cs-exposed.mc sunos3.5-cs-exposed.mc vangogh.mc hpux-cs-hidden.mc sunos3.5-cs-hidden.m The template tcpproto.mc is intended for a generic Internet site without UUCP connections. We'll use that as a starting point to develop our own. Since we don't want to modify the original file, we'll make a copy called test.mc and modify that. Although we won't show this in the examples below, it's a good idea to use a version control system like SCCS or RCS, or some other version control system to track changes you make to your configuration file template. Stripped of its comments (a copyright notice), blank lines, and an m4 directive, test.mc looks like this: include(' /m4/cf.m4') VERSIONID('@(#)tcpproto.mc 8.2 (Berkeley) 8/21/93') FEATURE(nouucp) MAILER(local) MAILER(smtp) This doesn't look like much, but m4 expands it to almost 600 lines. We'll look at this template line-by-line to show what it does. The line include(' /m4/cf.m4') must come first in all configuration file templates, immediately after any comments. It contains the macro definitions that m4 uses to build your configuration file, and if you don't include it here, nothing else will work. The VERSIONID() macro provides a place to put version information for the edification of humans sendmail ignores it. If you use RCS or SCCS, you can include their version information here. For instance, for RCS you can include the $Id$ keyword: VERSIONID('$Id$') and the RCS co (check-out) command expands this to: VERSIONID('$Id: test.mc,v 1.1 1994/03/26 21:46:12 joe Exp joe $') The FEATURE() macro is used to specify which features you want (or don't want). The line FEATURE(nouucp) in this configuration file template removes UUCP support from the resulting configuration file. Other features are documented in the README file mentioned above. Some features of particular interest are redirect, which provides a clever way to notify senders when someone leaves your site; and nullclient, which creates a bare-bones configuration file that knows just enough to forward mail to a relay. (See the template nullclient.mc for an example of its use.) The next two lines are MAILER() macros to specify the mailers included in this sendmail.cf. The MAILER() macro takes a single argument, the name of the mailer when m4 expands the MAILER() macro into one or more ruleset definitions, rules to select them in ruleset 0, and the rulesets given in the R= and S= flags. Selecting the smtp mailer actually causes three SMTP mailers to be included. The V8 templates also provide mailer definitions for UUCP mailers, a FAX mailer, and a POP (Post Office Protocol) mailer. See the README file for details. This is almost enough of a specification to create a working sendmail.cf for an SMTP-only site, but you'll want to tune it a little first with additional macros. The OSTYPE() macro also takes a single argument, the name of a file in /ostype. This file should contain definitions particular to your operating system, for instance, the location of the aliases file. A wide variety of operating system definitions are included with the V8 configuration files: $ cd /ostype $ ls aix3.m4 bsdi1.0.m4 hpux.m4 osf1.m4 sunos3.5.m4 aux.m4 dgux.m4 irix.m4 riscos4.5.m4 sunos4.1.m4 bsd4.3.m4 domainos.m4 linux.m4 sco3.2.m4 svr4.m4 bsd4.4.m4 dynix3.2.m4 nextstep.m4 solaris2.m4 ultrix4.1.m4 Since we're developing a configuration file for a Solaris 2.3 system, we'll look at that file: $ cat solaris2.m4 define('ALIAS_FILE', /etc/mail/aliases) define('HELP_FILE', /etc/mail/sendmail.hf) define('STATUS_FILE', /etc/mail/sendmail.st) define('LOCAL_MAILER_FLAGS', 'fSn') This is pretty straightforward the file gives the location of sendmail's auxiliary files on that system and specifies local mailer flags appropriate for the Solaris version of /bin/mail. We'll include an OSTYPE() macro just after the VERSIONID() macro, dropping the .m4 filename extension. The other things you may define in an OSTYPE file are documented in the README. You may also want to create a domain file and use the DOMAIN() macro to collect site-wide definitions such as your site's UUCP or BITNET relay hosts. You should only put things in this file that are true for all the hosts in your domain. If you only have a single host, you may want to forego creating a domain file and keep this information in your m4 template. The DOMAIN() macro takes a single argument, the name of a file in /domain. For instance, DOMAIN(gonzo) would cause m4 to look for a file named /domain/gonzo.m4. (Note that the .m4 extension is not included in the macro argument.) WARNING: If you copy one of the UCB templates that includes a DOMAIN() macro, make sure you change that line to use your own domain file, or delete it. A common feature to include in a domain file is the MASQUERADE_AS() macro, which causes all hosts using that sendmail.cf to masquerade as your mail hub. For example, if the Solaris 2.3 host we're building this configuration file for is one of many, all named sunX.gonzo.gov, the following line would cause all their outbound mail to be addressed as login@gonzo.gov, regardless of which workstation sent it: MASQUERADE_AS(gonzo.gov)dnl This line could also be included in the m4 template if you don't want to create a domain file. Now the template looks like this, with the lines we've added or changed in boldface type: include(' /m4/cf.m4') VERSIONID('$Id$') OSTYPE(solaris2) MASQUERADE_AS(gonzo.gov) FEATURE(nouucp) MAILER(local) MAILER(smtp) To create the working sendmail.cf, run m4 on the template: $ m4 test.mc > test.cf This creates a 600-line configuration file, which should be tested thoroughly before you install it. We will do just that in the next section, "Testing sendmail and sendmail.cf." But first, considering that building a sendmail.cf file from the V8 macros is so easy, you may be wondering why I went on at such length about the guts of it. After all, if including an SMTP mailer is as easy as typing MAILER(smtp), why bother to learn the grungy details? The first answer is that someday you'll probably need them; something will go wrong and you'll have to figure out exactly why your sendmail isn't working the way it should. You can't do that unless you understand the details. A second answer is that you can't properly test your sendmail.cf unless you know what's going on under the simplified m4 gloss. Finally, although the V8 configuration file templates are easy to work with compared to those included with previous versions of sendmail, they're still not exactly on a par with plugging in a new toaster and shoving in a couple of slices of rye. If sendmail were a toaster, instead of a single lever it would have hundreds of complicated knobs and dials, a thick instruction manual, and despite your best efforts, would periodically burst into flames. Testing sendmail and sendmail.cf Before installing a new or modified sendmail.cf you must test it thoroughly. Even small, apparently innocuous changes can lead to disaster, and as mentioned in the introduction to this chapter, people get really irate when you mess up the mail system. The first step in testing is to create a list of addresses that you know should work at your site. For instance, at gonzo.gov, an Internet site without UUCP connections, they know that the following addresses must work: joe joe@pc1.gonzo.gov joe@gonzo.gov If gonzo.gov has a UUCP link, those addresses must also be tested. Other addresses to consider include the various kinds of aliases (e.g., postmaster, a :include: list, an alias that mails to a file and one that mails to a program), nonlocal addresses, source-routed addresses, and so on. If you want to be thorough, you can create a test address for each legal address format in RFC822. Now that you've got your list of test addresses, you can use the -C and -bt options to see what happens. At a minimum you'll want to run the addresses through rulesets 3 and 0 to make sure they are routed to the correct mailer. An easy way to do this is to create a file containing the ruleset invocations and test addresses, and run sendmail on that. For instance, if the file addr.test contains the following lines: 3,0 joe 3,0 joe@pc1.gonzo.gov 3,0 joe@gonzo.gov you can test your configuration file test.cf by typing: $ sendmail -Ctest.cf -bt < addr.test rewrite: ruleset 3 input: joe rewrite: ruleset 3 returns: joe [etc.] You may also want to follow one or more addresses through the complete rewriting process. For instance, if an address resolves to the smtp mailer and that mailer specifies R=21, you can test recipient address rewriting with 3,2,21,4 test_address. If the sendmail.cf appears to work correctly so far, it's time to move on to sending some real letters. You can do so with a command like this: $ sendmail -v -oQ/tmp -Ctest.cf recipient < /dev/null The -v option tells sendmail to be verbose so you can see what's happening. Depending on whether the delivery is local or remote, you may see something as simple as joe Sent, or an entire SMTP dialogue. The -oQ/tmp tells sendmail to use /tmp as its queue directory. This is necessary because sendmail drops its super-user permissions when run with the -C option and can't write queue files into the normal mail queue directory. Because you are using the -C and -oQ options, sendmail also includes the following warning headers in the letter to help alert the recipient of possible mail forgery: X-Authentication-WARNING gonzo.gov: Processed from queue /tmp X-Authentication-WARNING gonzo.gov: Processed by joe with -C srvr.cf sendmail also inserts the header Apparently-to: joe because although you specified a recipient on the command line, there was none in the body of the letter. In this case the letter's body was taken from the empty file /dev/null, so there was no To: header. If you do your testing as the super-user, you can skip the -oQ argument, and sendmail won't insert the warning headers. You can avoid the Apparently-to: header by creating a file like this: To: recipient testing and using it as input instead of /dev/null. The recipient should be you so you can inspect the headers of the letter for correctness. In particular, return address lines must include an FQDN for SMTP mail. That is, a header like From: joe@gonzo is incorrect since it doesn't include the domain part of the name, but a header like From: joe@gonzo.gov is fine. You should repeat this testing for the same variety of addresses you used in the first tests. You may have to create special aliases that point to you for some of the testing. The amount of testing you do depends on the complexity of your site and the amount of experience you have, but a beginning system administrator should test things very thoroughly, even for apparently simple installations. Remember the flaming toaster. Installing sendmail and Friends Once you're satisfied that your sendmail and sendmail.cf work, you must decide where to install them. The most popular approach is to put sendmail and its other files in the same place that your vendor puts its distributed sendmail files. The advantage of this approach is conformity; if someone else familiar with your operating system tries to diagnose a mail problem, he will know where to look. However, some people prefer to install local programs separately from vendor programs, for several good reasons. First, operating system upgrades are usually easier when local modifications are clearly segregated from vendor programs. Second, some vendors, notably Sun Microsystems, release operating system patches that bundle together everything including the kitchen sink. If you naively install such a patch, you may inadvertently overwrite your V8 sendmail with your vendor's version, and it probably won't understand your V8 sendmail.cf. Therefore, you may want to install sendmail in a subdirectory of /usr/local, the traditional directory for local enhancements to the vendor's operating system. The locations of sendmail's auxiliary files are given in sendmail.cf, so you can either leave them in the vendor's usual locations or install them in /usr/local and modify the sendmail.cf to match. If you want to change the compiled-in location of the configuration file, redefine the C preprocessor macro _PATH_SENDMAILCF in src/Makefile and recompile sendmail. For example, add the definition: -D_PATH_SENDMAILCF=\"/usr/local/lib/sendmail.cf\" to the CFLAGS macro in the Makefile. Once you've decided where the files should go, look at the Makefile you used to compile sendmail and see if it agrees. The easiest way is to use make's -n option to see what would have happened. The results look like this for the V8 distribution's Makefile.Solaris: $ make -n install /usr/ucb/install -o root -g sys -m 6555 sendmail /usr/lib for i in /usr/ucb/newaliases /usr/ucb/mailq; do rm -f $i; ln -s /usr/lib/sendmai l $i; done /usr/ucb/install -c -o root -g sys -m 644 /dev/null \ /var/log/sendmail.st /usr/ucb/install -c -o root -g sys -m 444 sendmail.hf /etc/mail nroff -h -mandoc aliases.5 > aliases.0 nroff -h -mandoc mailq.1 > mailq.0 nroff -h -mandoc newaliases.1 > newaliases.0 nroff -h -mandoc sendmail.8 > sendmail.0 If this isn't what you want, modify the Makefile as necessary. Note that the sendmail manual pages use the 4.4BSD mandoc macros, which your system probably doesn't have. You can ftp the mandoc macros from the host ftp.uu.net, in the directory /systems/unix/bsd-sources/share/tmac. If your system doesn't have the /usr/ucb/install program, you can copy the new files instead, and use chown, chgrp and chmod to set the correct owner, group, and mode. However, if you're installing on top of your vendor's files, it's a good idea to first copy or rename them in case you ever need them again. After you install sendmail and its auxiliary files, rebuild the aliases database by running sendmail -bi. You'll also need to kill and restart your sendmail daemon. If your vendor's system uses a frozen configuration file (sendmail.fc), remove it; V8 sendmail doesn't use one. Modifying sendmail's Boot-Time Startup In its SMTP server role, sendmail starts when the system boots and runs continuously. If you install it in a non-standard location like /usr/local, you'll have to modify your system's startup scripts. Even if you install it in the standard location, you should ensure that the default system startup is correct for V8 sendmail. When SVR4 UNIX systems boot, they run a series of short shell scripts in the directories /etc/rcX.d, where the X corresponds to the system run level. For instance, shell scripts that bring the system to run level 2 are found in /etc/rc2.d. However, SVR4 systems have many run levels and some software subsystems should be started in each of them. Therefore, the shell scripts in /etc/rcX.d are located in /etc/init.d and linked to the files in the /etc/rcX.d directories. The /etc/init.d directory is therefore the best place to look for your sendmail startup script. The following example shows how to find how sendmail starts on a Solaris 2.3 system. Other SVR4 systems are similar: $ cd /etc/init.d $ grep sendmail * sendmail:#ident "@(#)sendmail 1.4 92/07/14 SMI" /* SVr4.0 1.5 */ sendmail:# /etc/init.d/sendmail - Start/Stop the sendmail daemon sendmail:# If sendmail is already executing, don't re-execute it. sendmail:if [ -f /usr/lib/sendmail -a -f /etc/mail/sendmail.cf ]; then sendmail: /usr/lib/sendmail -bd -q1h; sendmail:pid='/usr/bin/ps -e | /usr/bin/grep sendmail | [ ] sendmail:echo "usage: /etc/rc2.d/S88sendmail {start|stop}" $ NOTE: Some of the lines above are truncated and shown as [ ] due to page-width limitations. In this case the grep output shows that the vendor starts sendmail with a script named sendmail because each line of the grep output is prefixed with that filename. Examine the script sendmail to see if any changes are necessary. This script expects sendmail to be located in /usr/lib. If you install V8 sendmail somewhere else, you'll have to modify the script to match, changing paths like /usr/lib/sendmail to /usr/local/lib/sendmail. If the command-line flags in the script aren't what you want, change those too. Summary It's not possible in a single chapter to tell you all you must know about e-mail administration, but as Yogi Berra (or maybe that was Casey Stengel) once said, "You could look it up," and you should. There are a lot of things you'll only learn by reading the documentation mentioned previously in "Background Material and Other Sources." However, this chapter should give you a good basis for understanding the theory behind Internet e-mail delivery and enough of the specifics of V8 sendmail to get your e-mail system up and running. 1. For instance, sendmail sets $j to your system's fully qualified domain name (FQDN, e.g., acme.com). If your system's gethostbyname() function returns something other than the FQDN, you must define $j in sendmail.cf. 2. The local mailer omits the $@host. 3. Ruleset 0 is an exception to this rule. sendmail stops evaluating rules in ruleset 0 as soon as a rule resolves to a mailer. 4. Tokens are explained in "Tokens How sendmail Interprets Input Patterns." ©Copyright, Macmillan Computer Publishing. All rights reserved. [...]... the partitions.) During this operation, the news system (and probably the computer) are unavailable Configuring Your News Spool's File System Before you can use a disk partition, you must create a UNIX file system on it, using newfs, a front-end to the harder-to-user mkfs program (Some versions of UNIX use mkdev fs to create file systems Consult your system' s administration manual.) Unless you tell... 1.5.11 (10 February 199 1) ready at Sun Jul 17 19: 32:15 199 4 (posting ok) quit (If your telnet command doesn't support the mnemonic name for the port, substitute 1 19 for nntp in the command above.) In this example, no NNTP commands were given other than quit, but at least you can see that the NNTP server on some.host.edu is willing to let you read and post news Getting Help If your news system develops... problems System Startup Scripts and news cron Jobs A news system doesn't run on its own You must modify your system' s boot sequence to start parts of it and create cron jobs for the news user to perform other tasks INN supplies the file rc.news to start the news system when your computer boots For most SVR4 hosts, you should install it as /etc/init.d/news and make a hard link to it named /etc/rc2.d/S99news... network file system to share news Isolating the News Spool Most UNIX systems use the file system /var to contain files that grow unpredictably For instance, /var/mail contains user mailboxes and /var/log contains system log files Since the news spool is usually located in /var/spool/news, news articles may compete for space with potentially more important data such as e-mail Having your e-mail system grind... information is included on the UNIX Unleashed CD-ROM, some is available on the Internet, and some (from the technical newsgroups) you'll be able to apply only after you get your news system running The examples in this chapter assume you have an Internet site running the Network News Transfer Protocol (NNTP) If your networking capabilities are limited to the UNIX- to -UNIX Copy Program (UUCP), you're... Path The second way in which news systems avoid duplicate articles is the message identifier header, Message-ID Here is a sample Message-ID header: Message-ID: When a news article is created, the posting program, or some other part of the news system, generates this unique header Because no two articles have the same Message-ID header, the news system can keep track of the message... language Most USENET news is transferred either with the UUCP (UNIX- to -UNIX Copy Protocol) or NNTP UUCP is used by hosts that connect with modems over ordinary phone lines, and NNTP is the method of choice for hosts on the Internet As mentioned above, you should avoid UUCP if you can News Transport System Configuration Files The news transport system needs a lot of information about your site Minimally,... connect with them to read, post, and transfer news The news transport system' s configuration files provide this information The news administrator must set up these files when installing the news system and must modify them in response to changes, such as a new newsfeed The format of news transport system control files varies, but all current systems provide detailed configuration documentation Read it The... problems for the system administrator, because the amount of disk space used for news may vary a lot, and quickly You might think you've got plenty of space in your news system when you leave on Friday night, but then you get a call in the wee hours of Sunday morning telling you that the news file system is full If you've planned poorly, it might take more important things with it such as e-mail, system logging,.. .UNIX Unleashed, System Administrator's Edition - 25 News Administration By Jeff Smith and James Edwards Introduction The history of the USENET news service can be traced back to the original ARPANET The original ARPA-Internet . macros, which your system probably doesn't have. You can ftp the mandoc macros from the host ftp.uu.net, in the directory /systems /unix/ bsd-sources/share/tmac. If your system doesn't. default system startup is correct for V8 sendmail. When SVR4 UNIX systems boot, they run a series of short shell scripts in the directories /etc/rcX.d, where the X corresponds to the system run. Patterns." ©Copyright, Macmillan Computer Publishing. All rights reserved. UNIX Unleashed, System Administrator's Edition - 25 - News Administration By Jeff Smith and James Edwards Introduction The