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Sendmail Masquerading
11-16-2006
Sendmail Masquerading
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CHECKSENDMAIL(8) BSD System Manager's Manual CHECKSENDMAIL(8) NAME
checksendmail -- verify sendmail address transformations. SYNOPSIS
checksendmail [-a] [-d] [-b] [-C file.cf] [-b sendmail_binary] [-l log_file] [-r resolve] [-T test.address] DESCRIPTION
The checksendmail program is a perl script that aids the testing of sendmail(8) 's various configuration files. checksendmail passes typical addresses (supplied in input files) through sendmail and prints the results of the resolution and transformation routines. The input files contain a list of addresses, one per line. For example: user user@site user@site.com The input file can contain comments started with a # and blank lines. OPTIONS
-a Show aliasing of local addresses in mail address resolution phase of testing -d Preceed each address translation line with ruleset sequence summary -C file.cf Use the sendmail configuration file file.cf instead of the default /etc/sendmail.cf file. -b sendmail_binary Use the specified sendmail_binary as the path to invoke sendmail (instead of /usr/sbin/sendmail). -l log_file Log sendmail address test mode debugging output to log_file -r resolve Use resolve as the input file for the addresses to be used for mail resolving. Defaults to address.resolve. -T test.address Use test.address as the single address to test. Cannot be used in conjunction with file setting flags. EXAMPLES
The following command will pass the addresses in address.resolve through sendmail using the configuration information in myconfig.cf. example% cat address.resolve user user@site user@site.com example% checksendmail -C myconfig.cf system: myhost.gadget.com current dir: /tmp/Checksendmail resolve file: address.resolve sendmail binary: /usr/sbin/sendmail sendmail version: 8.9.3 config file: /etc/sendmail.cf config file version: V8/Berkeley Mail address resolution user --(ether )--> user[rmtc] user@site --(ether )--> user@site[rmtc] user@site.com --(ether )--> user@site.com[rmtc] `To' address transformations for mailer ether: user ----> user user@site ----> user@site user@site.com ----> user@site.com `From' address transformations for mailer ether: user ----> user user@site ----> user user@site.com ----> user The first section of the output shows how the addresses in the input files are resolved by sendmail(8). Consider the following output line: user@site.com --(ether )--> user@site.com[rmtc] The input address user@site.com resolves to use the ether mailer. That mailer is directed to send the mail to to the user user@site.com at site rmtc (as indicated in the square brackets). The two later sections of output show how the addresses specified as the To and From address are transformed in the text of the headers. In the example above, the To addresses are untouched. The From addresses, however, all lose their machine information on the way through the mailer: user@site ----> user This may be desirable when using a configuration file on a workstation which is to be hidden as a mailhost from the rest of the network. The following is a set of addresses used at one site for the purposes of testing address resolution. Comments after the addresses detail why particular addresses are present: user Standard trivial address user@rmtc qualified at one level user@rmtc.central qualified at two levels user@rmtc.central.sun.com qualified all the way rmtc!user local but specified as uucp user@summit a workstation (normally delivered locally, though) user@summit.central same but more qualified user@summit.central.sun.com same but fully qualified summit!user same but specified as uucp user@prisma Backward compatibility tests user@prisma.com prisma!user user@central Superior domain testing user@machine.central more qualified, but unknown user@summit.central more qualified and known user@eng name in faraway domain user@machine.eng unknown machine in faraway domain user@summit.eng local machine, far away domain user@hoback far away machine user@machine apparently local but unknown machine user@sun.com Standard trivial address user@machine.dom.sun.com fully qualified but unknown machine user@foo.com standard, known, really far away domain user@foo.dom standard, unknown, really far away domain site!user Single level uucp site1!site2!user Double level uucp user@foo.dom@bar.dom Trickier address site!user@foo.dom Mixed uucp/domain site!user@uunet.uu.net Mixed double uucp/domain NOTES
Note that checksendmail is a perl script. If your site does not have perl(1), it can be obtained via anonymous ftp from ftp.uu.net. sendmail requires that the user have access to directory specified by the OQ parameter in the configuration file (normally /usr/spool/mqueue). checksendmail verifies that the user has access to this directory before allowing the test to continue. AUTHORS
Gene Kim Rob Kolstad Jeff Polk Modified by Robert Harker SEE ALSO
sendmail(8) BSD
November 14, 2000 BSD