Am So, den 15.08.2004 schrieb Harry Putnam um 2:59: sendmail2.mc Is newsguy.com your domain? I ask because of the central and important comment on masquerading from the cf/README: "The masquerade name is not normally canonified, so it is important that it be your One True Name, that is, fully qualified and not a CNAME. However, if you use a CNAME, the receiving side may canonify it for you, so don't think you can cheat CNAME mapping this way." (http://www.sendmail.org/m4/masquerading_relaying.html) It makes not much sense to offer a smart host which requires a resolvable FQDN. How should people at home with DSL, modem or ISDN connection mail throught their ISP's smart host? It is the task of the ISP's smart host to jump into this gap and offer such linked users the ability to use their own MTA without the risk that many if not most of the recipient MTAs reject mail coming from them, just because they have no resolvable FQDN. Whether the contacting host announces himself with a resolvable FQDN at HELO/EHLO depends from settings of the real hostname, the domain name (if set in sendmail.mc) and from masquerading settings (if are defined). Genericstable does only rewrite the sender envelope address. Important is that your bogus (internal) FQDN is internally resolvable. Using a --> GENERICS_DOMAIN(`local.net0')dnl belongs to the set, else the genericstable feature would not know for which domains to look for rewriting. Maybe my misunderstanding at this point and just to clear out: if you only change map files (the text files from which hashes/.db files are generated) you do not need to restart Sendmail. That is one sense of using these hash files. A Sendmail daemon restart is only necessary if you change the central configuration files ending with .cf (sendmail.cf and submit.cf) and after changes on pure text files like local-host-names, generics-domains or trusted-users. Please check what following prints out: echo "$=M" | /usr/lib/sendmail -bt -d0 echo "$=G" | /usr/lib/sendmail -bt The hosts file looks perfect. [ ... ] [ ... ] [ ... ] [ ... ] [ ... ] There is missing: MASQUERADE_DOMAIN(`localhost')dnl MASQUERADE_DOMAIN(`localhost.localdomain')dnl MASQUERADE_DOMAIN(`reader.local.net0')dnl Both commands from above for class{M} and class{G} have to show proper settings. Alexander -- Alexander Dalloz | Enger, Germany | GPG key 1024D/ED695653 1999-07-13 Fedora GNU/Linux Core 2 (Tettnang) kernel 2.6.7-1.494.2.2smp Serendipity 04:49:12 up 10 days, 22:16, load average: 0.22, 0.27, 0.39

Alexander Dalloz <alexander.dalloz(a)uni-bielefeld.de&gt; writes: [...] No, as is explained further along, my `domain' is a home made one: local.net0 This confuses me to no end: First the README shows: `MASQUERADE_AS(`host.domain')' (It shows `host' where first part of domain name should be). As I understand it the naming convention is: host.domain.designator = reader.local.net0 Using my FQDN that would be `reader.net0' rather than `reader.local.com' So I've assumed it really wants `network.domain'. If one uses ones `One True Name', in this case `1ocal.net0' (I guess it means the last part of my fqdn?) then it is not masquerading as something else. But the paragraph just proceeding the one you quoted says in part: You can have your host masquerade as another using MASQUERADE_AS(`host.domain') This causes mail being sent to be labeled as coming from the indicated host.domain, rather than $j. But `$j' is my fqdn (reader.local.net0). Clearly the intent is to parade as something you are not. So inserting `local.net0' there would not accomplish that goal it seems. What you say does make sense, and shows a major flaw in my picture of what is happening and how it all works. Ok, that is more I didn't understand (about genericstable). OK, I can see how that might help and have even tried it as I recall. You may notice it appears in the posted sendmail1.mc. IE the one that causes bounces. If you reread that you'll see I'm describing a chain of events: 1) edit *.mc and generate sendmail.cf 2) build genericstable 3) restart sendmail It was point 1 that required the restart. [...] [...] Version 8.13.1 Compiled with: DNSMAP HESIOD HES_GETMAILHOST LDAPMAP LOG MAP_REGEX MATCHGECOS MILTER MIME7TO8 MIME8TO7 NAMED_BIND NETINET NETINET6 NETUNIX NEWDB NIS PIPELINING SASLv2 SCANF STARTTLS TCPWRAPPERS USERDB USE_LDAP_INIT ============ SYSTEM IDENTITY (after readcf) ============ (short domain name) $w = reader (canonical domain name) $j = reader.local.net0 (subdomain name) $m = local.net0 (node name) $k = reader.local.net0 ======================================================== ADDRESS TEST MODE (ruleset 3 NOT automatically invoked) Enter <ruleset> <address> # echo "$=G" | /usr/lib/sendmail -bt ADDRESS TEST MODE (ruleset 3 NOT automatically invoked) Enter <ruleset> <address> OK, I got something right... Maybe, but sendmail2.mc which contains only MASQUERADE_AS(`newsguy.com')dnl FEATURE(masquerade_envelope)dnl (concerning masquerading) Is the one that works. The other (sendmail1.mc) does not. So that leaves some questions. But first let me input some further information. I've now noticed that I can put just about anything in that field MASQUERADE_AS(`whizbang.net')dnl is currently in sendmail.cf and it works ok. I'll send this message that way and there will be no bounce. So I'm re-evaluating what that actually does. Its not doing what I thought at all but is still doing something. So removing all generics language I'll run a test with the following *.mc. Note it contains two masquerade entries: MASQUERADE_AS(`whizbang.net')# [HP 08/12/04 13:38 Not used since]dnl FEATURE(masquerade_envelope)# [HP 08/12/04 13:38 Not used since]dnl If I remove either one of them my mail bounces immediately. Sorry to include another full *.mc but it seems the only way to avoid any misunderstanding or confusion about what is or is not present in it. So with all generics stuff removed with this *mc in place my mail goes thru, can you tell me what the masquerade stuff is doing that allows my mail to go thru, as you see it is set to `whizbang.net': divert(-1)dnl include(`/usr/share/sendmail-cf/m4/cf.m4')dnl VERSIONID(`setup for Red Hat Linux')dnl OSTYPE(`linux')dnl define(`SMART_HOST',`smtp.newsguy.com') define(`confDEF_USER_ID',``8:12'')dnl define(`confTO_CONNECT', `1m')dnl define(`confTRY_NULL_MX_LIST',true)dnl define(`confDONT_PROBE_INTERFACES',true)dnl define(`PROCMAIL_MAILER_PATH',`/usr/bin/procmail')dnl define(`ALIAS_FILE', `/etc/aliases')dnl define(`STATUS_FILE', `/var/log/mail/statistics')dnl define(`confUSERDB_SPEC', `/etc/mail/userdb.db')dnl define(`confPRIVACY_FLAGS', `authwarnings,novrfy,noexpn,restrictqrun')dnl define(`confAUTH_OPTIONS', `A')dnl define(`confTO_IDENT', `0')dnl FEATURE(`no_default_msa',`dnl')dnl FEATURE(`smrsh',`/usr/sbin/smrsh')dnl FEATURE(`virtusertable')dnl FEATURE(redirect)dnl FEATURE(always_add_domain)dnl FEATURE(use_cw_file)dnl FEATURE(use_ct_file)dnl FEATURE(local_procmail,`',`procmail -t -Y -a $h -d $u')dnl FEATURE(`access_db',`hash -T<TMPF> -o /etc/mail/access.db')dnl FEATURE(`blacklist_recipients')dnl FEATURE(`accept_unresolvable_domains')dnl LOCAL_DOMAIN(`localhost.localdomain')dnl MASQUERADE_AS(`whizbang.net')# [HP 08/12/04 13:38 Not used since]dnl FEATURE(masquerade_envelope)# [HP 08/12/04 13:38 Not used since]dnl MAILER(smtp)dnl MAILER(procmail)dnl

Ok Henry, let me start a new path through all the confusion (I think I did some mis-expressing meanwhile in both threads about this topic). Both, masquerade and genericstable, have the same purpose: to rewrite the sender envelope mail address. Whether masquerading is preferable or genericstable depends on the specific situation. It is possible to mix both, from my own testing I see that a genericstable rewriting overrides masquerade settings. 1) masquerading You define the @FQDN rewrite address with MASQUERADE_AS(`FQDN') which will rewrite the mail from the host itself and all in class {M} to have a header address coming from there. To make sure the envelope address is properly set too, there is the FEATURE(masquerade_envelope) instruction. To not only masquerade the single mail host itself but all hosts inside the net, you can use FEATURE(masquerade_entire_domain). MASQUERADE_DOMAIN(foo) fill the class{M}. The masquerading (mail header and envelope) sender address rewriting takes place as long the sender address (@domain-part) previous to rewriting is something inside the class {M}. If the sender chooses an address in his mail client which is different from anything in class {M} no rewriting is done by masquerading. On the other hand, mail sending using mail or sendmail (without parameter -f) from the masq host itself or any masqueraded other will lead to address rewriting. 2) genericstable The FEATURE(genericstable) is a (hashed) map file with on the LHS (left hand side) has the user or address which shall be rewritten and on the RHS (right hand side) the address to which the LHS shall be converted. class {G} is empty by default and is filled by entries placed into the plain test file generics-domains. FEATURE(generics_entire_domain) is the parallel to FEATURE(masquerade_entire_domain). How it works: if mail is processed and the FEATURE(genericstable) is active, then the @domain-part is looked up in class {G} whether it is to be rewritten. If the @domain-part is part of class {G} then the genericstable map file is taken and searched for a matching LHS part. If none found nothing happens, if an entry found the address is rewritten with the content of the RHS. 3) When address rewriting is needed When you run your own Sendmail and you have no public resolvable FQDN for that mail host, assigned the FQDN to your IP address using an DNS record, you need address rewriting for those cases where the origin mail address will be the private, non resolvable domain address. Examples for this are notification mails sent out by cronjobs or "hand made" mail using the "mail" command. Mail clients setting the envelope sender address correctly, you do not need masquerading or genericstable rewriting. Using the smart host of your ISP or from any other service does not heal this situation. Though it is recommended to use such a smart host from dial-in homed connections because otherwise your Sendmail (fits for other MTAs as well) will directly deliver to the recipient's MTA, and meanwhile many of those do not accept incoming connections by dial-up IPs (because of need for anti SPAM fighting). The smart host does not rewrite the sender address, but it should reject attempts to relay, when he (the smart host) acknowledges a public non-existent domain part in the sender's mail address. 4) example setup Given your Sendmail host name is satyr.local.net0 and you send mail through it, either locally or from a host in the same private net (IP, name does not need to be the same) using your Sendmail for sending, and you do not use a mail client which sets a proper (proper because public existing and deliverable) mail address, then you need address rewriting either with masquerading or genericstable. Let us take the masquerading setup. MASQUERADE_AS(`newsguy.com')dnl FEATURE(masquerade_envelope)dnl This is what you did use. If newsguy.com is your controlled domain, it is not big problem, because you can create valid email addresses for that domain for each sender you use through your Sendmail. It is then a problem, if you for example have only 1 email address like hputnam(a)newsguy.com but no other. Why? Well, imagine the case mail is sent out by a root's cronjob. You know how it is rewritten? Yes, to root(a)newsguy.com. Where does a reply could go? Right, not to the sender. Same is valid for all other cases where the mail is not initiated by your local user with name hputnam. In your last mail you wrote you used (at least tested with) MASQUERADE_AS(`whizbang.net') address rewriting and that it succeeded when sending through your ISP's smart host. It of course worked, rather than sending with an address of @satyr.local.net0, because whizbang.net is a public resolvable thus valid domain name (does not matter whether a mail server runs for it). So the smart host verifies it is existing and accepts it for relaying. Of course your mail sent out has now the sender address hputnam(a)whizbang.net what you hardly want. If you would use for the MASQUERADE_AS name `whozbang.net' your ISP's smart host would reject the relay attempt. Address rewriting using genericstable would work similar in your case, you only have to respect the differences. Especially the differences may lead to the decision to give genericstable the preference over masquerading, because when using masquerading you won't get an error when sending with a non existing email address while rewriting to `newsguy.com' (not your domain as you said before) for example. With genericstable you have to define positive cases, where a rewriting has to take place. And in each case not rewrite target is found you or a script sending out with a non rewritten mail address will cause an error immediately. I really hope my explanations do not cause a lot more confusion and questions :) But feel free to ask. Alexander -- Alexander Dalloz | Enger, Germany | GPG key 1024D/ED695653 1999-07-13 Fedora GNU/Linux Core 2 (Tettnang) kernel 2.6.7-1.494.2.2smp Serendipity 18:58:51 up 12 days, 12:26, load average: 0.35, 0.47, 0.45

On Tue, 2004-08-17 at 03:03, Alexander Dalloz wrote: Actually I found out there IS! 2 Months after going the manual method of doing the above pseudo code (implemented as per code below), which works by the way, just a bit manual. I found out that the pseudo code which I wanted actually exists. It's actually marked as /usr/share/sendmail-cf/README confFALLBACK_MX FallbackMXhost [undefined] Fallback MX host. Note the !!undefined!! Finally today, I came to know how it's used. As the name states, it's a Fallback mechanism in case things don't work out with the send direct to MX approach. It Works. Doing an ethereal trace, I noted that it first tried to lookup the MX of the domain which mail is to be sent to, and then it tries to send it via that path, since mail can't go that path, due to errors, it will re-try, this time with the fallback MX Host. Mail then gets through. ==========MY Original Script - REdundant Now============= #!/bin/sh # # This is to automatically change from using MX and to using # SMART HOST # # Sept 24 2004 # 4pm #if [ id != 0 ]; then # echo "Got Root?" # exit 1 #fi case "$1" in MX) echo "Altering Sendmail Config to use MX" mv /etc/mail/sendmail.mc /etc/mail/sendmail.mc.office mv /etc/mail/sendmail.mc.MX /etc/mail/sendmail.mc touch /etc/mail/sendmail.mc sleep 1 m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf /etc/init.d/sendmail restart ;; office) echo "Altering Sendmail Config to use Smart Host" mv /etc/mail/sendmail.mc /etc/mail/sendmail.mc.MX mv /etc/mail/sendmail.mc.office /etc/mail/sendmail.mc touch /etc/mail/sendmail.mc sleep 1 m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf /etc/init.d/sendmail restart ;; status) if [ "`cat /etc/mail/sendmail.cf | grep wdc | cut -d\( -f1`" == "DSsmart-host.entry.com" ] ; then echo "Sendmail currently configured with SMART_HOST" else echo "Sendmail currently configured to use MX" fi ;; *) echo "Usage: $0 {MX | office | status}" ;; esac exit 0