Rocksolid Light

Welcome to novaBBS (click a section below)

mail  files  register  newsreader  groups  login

Message-ID:  

"So why don't you make like a tree, and get outta here." -- Biff in "Back to the Future"


computers / alt.os.linux.slackware / Re: Sendmaail, resolv.conf, DNS

SubjectAuthor
* Sendmaail, resolv.conf, DNSMike Spencer
+* Re: Sendmaail, resolv.conf, DNSRich
|`* Re: Sendmaail, resolv.conf, DNSMike Spencer
| `- Re: Sendmaail, resolv.conf, DNSRich
+* Re: Sendmaail, resolv.conf, DNSMarco Moock
|`* Re: Sendmaail, resolv.conf, DNSMike Spencer
| +- Re: Sendmaail, resolv.conf, DNSMarco Moock
| `* Re: Sendmaail, resolv.conf, DNSJim
|  `- Re: Sendmaail, resolv.conf, DNSJerry Peters
`* Re: Sendmaail, resolv.conf, DNSLew Pitcher
 `* Re: Sendmaail, resolv.conf, DNSMike Spencer
  +- Re: Sendmaail, resolv.conf, DNSLew Pitcher
  `* Re: Sendmaail, resolv.conf, DNSRich
   `- Re: Sendmaail, resolv.conf, DNSMike Spencer

1
Sendmaail, resolv.conf, DNS

<878r32smno.fsf@enoch.nodomain.nowhere>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2196&group=alt.os.linux.slackware#2196

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: mds...@bogus.nodomain.nowhere (Mike Spencer)
Newsgroups: alt.os.linux.slackware
Subject: Sendmaail, resolv.conf, DNS
Date: 29 Feb 2024 22:36:59 -0400
Organization: Bridgewater Institute for Advanced Study - Blacksmith Shop
Lines: 51
Sender: mds@enoch.nodomain.nowhere
Message-ID: <878r32smno.fsf@enoch.nodomain.nowhere>
Injection-Info: dont-email.me; posting-host="3ae431ac2f98bce801fabcae0338d598";
logging-data="973873"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX197Czp5x5MQ+d28tOW5p6nRQYWhfUJJOjA="
Cancel-Lock: sha1:1RabeWa0kvcv9WeZBJGoAZkr/TI=
X-Newsreader: Gnus v5.7/Emacs 20.7
X-Clacks-Overhead: 4GH GNU Terry Pratchett
 by: Mike Spencer - Fri, 1 Mar 2024 02:36 UTC

Not limited to Slackware but as a long-time Slackware user, this group
seems more like home to me...

Given sendmail 8.17.1 running as daemon:

/usr/sbin/sendmail -L sm-mta -bd -q25m
/usr/sbin/sendmail -L sm-msp-queue -Ac -q25m

is there a way to query the daemon to learn what nameserver(s) it is
using?

Why do I ask?

AFAICT, unlike some other programs which appear to query
/etc/rsolv.conf each time they use DNS, sendmail reads
/etc/resolv.conf when it starts and stores the IP addresses of
nameservers internally. If /etc/resolv.conf changes, that change is
not noted by sendmail. The result is a prolonged, fruitless attempt
to resolve a hostname from nameservers that will no longer respond to
the request from the then-current net-facing IP address of localhost.

Details

My usual setup is a desktop cabled to a router that is in turn cabled
to a gateway device using ISP "A".

The sendmail daemon's only task is to deliver outgoing mail to a
smarthost with TLS and AUTH.

At times, using wicd, I disconnect from the router and reconnect via
wi-fi, using a cell phone served by ISP "B" as an access point. Wicd
replaces /etc/resolv.conf with one that references the nameservers of
ISP "B". Apps such as a web browser and Usenet news proceed as
expected after the change but sendmail fails to deliver messages to
the remote smarthost.

Restarting sendmail fixes this.

It would be convenient to be able to query the sendmail daemon to see
what it was using as nameservers and avoid a restart if one isn't
needed.

I have the Bat Book but don't find an answer there.

A way to do this or enlightenment of ignorance on my part -- things I
don't know I don't know :-) -- welcome.

--
Mike Spencer Nova Scotia, Canada

Re: Sendmaail, resolv.conf, DNS

<urri2f$11ui1$1@dont-email.me>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2197&group=alt.os.linux.slackware#2197

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: ric...@example.invalid (Rich)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: Fri, 1 Mar 2024 03:29:19 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 29
Message-ID: <urri2f$11ui1$1@dont-email.me>
References: <878r32smno.fsf@enoch.nodomain.nowhere>
Injection-Date: Fri, 1 Mar 2024 03:29:19 -0000 (UTC)
Injection-Info: dont-email.me; posting-host="8ef4264d65e4b5af98262fada3f3b2a6";
logging-data="1112641"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19srX5KPziLo5nBfPk36tUs"
User-Agent: tin/2.6.1-20211226 ("Convalmore") (Linux/5.15.139 (x86_64))
Cancel-Lock: sha1:+vPp4XC02VmVfcD2O0HKsO9m3j4=
 by: Rich - Fri, 1 Mar 2024 03:29 UTC

Mike Spencer <mds@bogus.nodomain.nowhere> wrote:
> The sendmail daemon's only task is to deliver outgoing mail to a
> smarthost with TLS and AUTH.
>
> At times, using wicd, I disconnect from the router and reconnect via
> wi-fi, using a cell phone served by ISP "B" as an access point. Wicd
> replaces /etc/resolv.conf with one that references the nameservers of
> ISP "B". Apps such as a web browser and Usenet news proceed as
> expected after the change but sendmail fails to deliver messages to
> the remote smarthost.
>
> Restarting sendmail fixes this.
>
> It would be convenient to be able to query the sendmail daemon to see
> what it was using as nameservers and avoid a restart if one isn't
> needed.

Not sure that is possible. Sendmail (and mail servers in general) are
going to assume stable, static IP values, and so it is very doubtful
there is any official way to ask the daemon what nameservers it is
using. Reason being that in a static environment, there's no need to
ever bother doing so.

But, if the sendmail daemon's only task is to deliver outgoing mail to
a smarthost, what about configuring sendmail with the IP address of the
smart host? Then it won't need to do a DNS lookup to get the smart
host's IP, and changing resolv.conf won't matter to it. All that will
matter is that it can connect to that IP address via the current in use
network path.

Re: Sendmaail, resolv.conf, DNS

<urs39m$14o1e$3@dont-email.me>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2200&group=alt.os.linux.slackware#2200

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: mm+use...@dorfdsl.de (Marco Moock)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: Fri, 1 Mar 2024 09:23:17 +0100
Organization: A noiseless patient Spider
Lines: 11
Message-ID: <urs39m$14o1e$3@dont-email.me>
References: <878r32smno.fsf@enoch.nodomain.nowhere>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Injection-Date: Fri, 1 Mar 2024 08:23:18 -0000 (UTC)
Injection-Info: dont-email.me; posting-host="78bc249caea6354d47e2d323124334e1";
logging-data="1204270"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18L5fp+okvv78Yn54Qa/TIB"
Cancel-Lock: sha1:/kFe1pKvExcXdNlqbzhH7JMts1g=
 by: Marco Moock - Fri, 1 Mar 2024 08:23 UTC

Am 29.02.2024 schrieb Mike Spencer <mds@bogus.nodomain.nowhere>:

> Not limited to Slackware but as a long-time Slackware user, this group
> seems more like home to me...

Your question fits in comp.mail.sendmail.

IIRC for other operating systems a mechanism exists that automatically
reloads sendmail when the network changes (NetworkManager).
Maybe you can implement that in slackware too.

Re: Sendmaail, resolv.conf, DNS

<urso0s$18tpq$1@dont-email.me>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2201&group=alt.os.linux.slackware#2201

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: lew.pitc...@digitalfreehold.ca (Lew Pitcher)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: Fri, 1 Mar 2024 14:17:00 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 48
Message-ID: <urso0s$18tpq$1@dont-email.me>
References: <878r32smno.fsf@enoch.nodomain.nowhere>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Injection-Date: Fri, 1 Mar 2024 14:17:00 -0000 (UTC)
Injection-Info: dont-email.me; posting-host="be97da58100b10299b55d1e6f1a9c369";
logging-data="1341242"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19F5U8yhi294sgwY+Eq1hT+1+0ZRtB2vDE="
User-Agent: Pan/0.139 (Sexual Chocolate; GIT bf56508
git://git.gnome.org/pan2)
Cancel-Lock: sha1:uok7zImdvfAyVXX22LHSGXXVfKc=
 by: Lew Pitcher - Fri, 1 Mar 2024 14:17 UTC

On Thu, 29 Feb 2024 22:36:59 -0400, Mike Spencer wrote:

> Not limited to Slackware but as a long-time Slackware user, this group
> seems more like home to me...
>
> Given sendmail 8.17.1 running as daemon:
>
> /usr/sbin/sendmail -L sm-mta -bd -q25m
> /usr/sbin/sendmail -L sm-msp-queue -Ac -q25m
>
> is there a way to query the daemon to learn what nameserver(s) it is
> using?
[snip]
> My usual setup is a desktop cabled to a router that is in turn cabled
> to a gateway device using ISP "A".
>
> The sendmail daemon's only task is to deliver outgoing mail to a
> smarthost with TLS and AUTH.
>
> At times, using wicd, I disconnect from the router and reconnect via
> wi-fi, using a cell phone served by ISP "B" as an access point. Wicd
> replaces /etc/resolv.conf with one that references the nameservers of
> ISP "B". Apps such as a web browser and Usenet news proceed as
> expected after the change but sendmail fails to deliver messages to
> the remote smarthost.
>
> Restarting sendmail fixes this.
[snip]

I think that you are trying to solve the wrong problem. The problem isn't
that sendmail caches the address of the DNS server, but that you are
using a DNS server who's address may change over time.

You could just run a caching nameserver on your slackware box, and
resolve /all/ DNS queries against that server. This way, the DNS
server maintains a fixed address (perhaps, "localhost", in your case)
and sendmail doesn't have to fish about for DNS resolution.

A caching DNS server adds very little to the system overhead, and,
beyond the initial setup, needs little or no maintenance. It gives
the added benefit of adding a bit more security to your DNS queries,
in that your ISP /does not/ handle the queries, /can't/ log or track
them, and /can't/ substitute their own sponsored/edited/redirected
answers.

--
Lew Pitcher
"In Skills We Trust"

Re: Sendmaail, resolv.conf, DNS

<87le71quix.fsf@enoch.nodomain.nowhere>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2204&group=alt.os.linux.slackware#2204

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: mds...@bogus.nodomain.nowhere (Mike Spencer)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: 01 Mar 2024 21:42:14 -0400
Organization: Bridgewater Institute for Advanced Study - Blacksmith Shop
Lines: 36
Sender: mds@enoch.nodomain.nowhere
Message-ID: <87le71quix.fsf@enoch.nodomain.nowhere>
References: <878r32smno.fsf@enoch.nodomain.nowhere> <urri2f$11ui1$1@dont-email.me>
Injection-Info: dont-email.me; posting-host="497e907df30fbe30ab2178b5dfe50bbb";
logging-data="1625810"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+HYeizsUE8bHr+XMe7cRj5w2mH8PzsDC0="
Cancel-Lock: sha1:wHiiFgnDPn84ujlHGcOVg+7PuQM=
X-Clacks-Overhead: 4GH GNU Terry Pratchett
X-Newsreader: Gnus v5.7/Emacs 20.7
 by: Mike Spencer - Sat, 2 Mar 2024 01:42 UTC

Rich <rich@example.invalid> writes:

> Mike Spencer <mds@bogus.nodomain.nowhere> wrote:
>
>> It would be convenient to be able to query the sendmail daemon to see
>> what it was using as nameservers and avoid a restart if one isn't
>> needed.
>
> Not sure that is possible. Sendmail (and mail servers in general) are
> going to assume stable, static IP values, and so it is very doubtful
> there is any official way to ask the daemon what nameservers it is
> using. Reason being that in a static environment, there's no need to
> ever bother doing so.
>
> But, if the sendmail daemon's only task is to deliver outgoing mail to
> a smarthost, what about configuring sendmail with the IP address of the
> smart host? Then it won't need to do a DNS lookup to get the smart
> host's IP, and changing resolv.conf won't matter to it. All that will
> matter is that it can connect to that IP address via the current in use
> network path.

That's a good idea. I'm using the mailertable mechanism which, AIUI, is
distinct from the smarthost one. But I could put the IP address in
the mailertable & authinfo files, rebuild the corresponding .db files
and see if the problem goes away. Don't have to mess with sendmail.cf.

My mail provider is a mom&pop ISP that seems to jockey IP addresses
around from time to time but I can stay alert to that.

Having an unwelcome episode of vertigo just now so I'm not going to
try typing config files through the fog. I'll get to it.

Tnx,
--
Mike Spencer Nova Scotia, Canada

Re: Sendmaail, resolv.conf, DNS

<87h6hpqu9o.fsf@enoch.nodomain.nowhere>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2205&group=alt.os.linux.slackware#2205

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: mds...@bogus.nodomain.nowhere (Mike Spencer)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: 01 Mar 2024 21:47:47 -0400
Organization: Bridgewater Institute for Advanced Study - Blacksmith Shop
Lines: 25
Sender: mds@enoch.nodomain.nowhere
Message-ID: <87h6hpqu9o.fsf@enoch.nodomain.nowhere>
References: <878r32smno.fsf@enoch.nodomain.nowhere> <urs39m$14o1e$3@dont-email.me>
Injection-Info: dont-email.me; posting-host="497e907df30fbe30ab2178b5dfe50bbb";
logging-data="1625810"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19sm1VsTZw2f+sKD3bDBMMxYr6kip7CtCA="
Cancel-Lock: sha1:5/PXvy/biJiHPYTXeiRzImTdumE=
X-Newsreader: Gnus v5.7/Emacs 20.7
X-Clacks-Overhead: 4GH GNU Terry Pratchett
 by: Mike Spencer - Sat, 2 Mar 2024 01:47 UTC

Marco Moock <mm+usenet@dorfdsl.de> writes:

> Am 29.02.2024 schrieb Mike Spencer <mds@bogus.nodomain.nowhere>:
>
>> Not limited to Slackware but as a long-time Slackware user, this group
>> seems more like home to me...
>
> Your question fits in comp.mail.sendmail.

Yeah. Hacking sendmail is really above my pay grade. :-) I'll go
there if I get stuck.

> IIRC for other operating systems a mechanism exists that automatically
> reloads sendmail when the network changes (NetworkManager).
> Maybe you can implement that in slackware too.

Hmm. I use wicd because NetworkManager demands a "tray" that isn't
supported by my favored window manager (twm). But wicd does seems to
do the right thing about swapping the resolv.conf files back and
forth. I'll have a closer look.

Tnx,
--
Mike Spencer Nova Scotia, Canada

Re: Sendmaail, resolv.conf, DNS

<87cysdqtu9.fsf@enoch.nodomain.nowhere>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2206&group=alt.os.linux.slackware#2206

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: mds...@bogus.nodomain.nowhere (Mike Spencer)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: 01 Mar 2024 21:57:02 -0400
Organization: Bridgewater Institute for Advanced Study - Blacksmith Shop
Lines: 44
Sender: mds@enoch.nodomain.nowhere
Message-ID: <87cysdqtu9.fsf@enoch.nodomain.nowhere>
References: <878r32smno.fsf@enoch.nodomain.nowhere> <urso0s$18tpq$1@dont-email.me>
Injection-Info: dont-email.me; posting-host="497e907df30fbe30ab2178b5dfe50bbb";
logging-data="1625810"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19O101GyMMedbPQZLM2CozmdRqQDsPIEG8="
Cancel-Lock: sha1:GLG3hvimV+pV57RHmj8tlfUbk/s=
X-Clacks-Overhead: 4GH GNU Terry Pratchett
X-Newsreader: Gnus v5.7/Emacs 20.7
 by: Mike Spencer - Sat, 2 Mar 2024 01:57 UTC

Lew Pitcher <lew.pitcher@digitalfreehold.ca> writes:

> On Thu, 29 Feb 2024 22:36:59 -0400, Mike Spencer wrote:
>
>> At times, using wicd, I disconnect from the router and reconnect via
>> wi-fi, using a cell phone served by ISP "B" as an access point. Wicd
>> replaces /etc/resolv.conf with one that references the nameservers of
>> ISP "B". Apps such as a web browser and Usenet news proceed as
>> expected after the change but sendmail fails to deliver messages to
>> the remote smarthost.
>>
>> Restarting sendmail fixes this.
> [snip]
>
> I think that you are trying to solve the wrong problem. The problem isn't
> that sendmail caches the address of the DNS server, but that you are
> using a DNS server who's address may change over time.
>
> You could just run a caching nameserver on your slackware box, and
> resolve /all/ DNS queries against that server. This way, the DNS
> server maintains a fixed address (perhaps, "localhost", in your case)
> and sendmail doesn't have to fish about for DNS resolution.

I never thought of that. The caching nameserver would have to be able
to go to the right remote nameserver to update itself but that might
be handled correctly. One more thing to maintain kinda contravenes my
preference for KISS but I'll have a look at that.

> A caching DNS server adds very little to the system overhead, and,
> beyond the initial setup, needs little or no maintenance. It gives
> the added benefit of adding a bit more security to your DNS queries,
> in that your ISP /does not/ handle the queries, /can't/ log or track
> them, and /can't/ substitute their own sponsored/edited/redirected
> answers.

A potential problem, yeah. IIRC, I've only seen it happen twice, once
using somebody's wi-fi where their router did DNS weirdly. I forget
the details of the other case but it became publicly known and went
away after public protest.

Tnx,
--
Mike Spencer Nova Scotia, Canada

Re: Sendmaail, resolv.conf, DNS

<uru2u5$1d7qp$1@dont-email.me>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2207&group=alt.os.linux.slackware#2207

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: lew.pitc...@digitalfreehold.ca (Lew Pitcher)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: Sat, 2 Mar 2024 02:29:26 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 75
Message-ID: <uru2u5$1d7qp$1@dont-email.me>
References: <878r32smno.fsf@enoch.nodomain.nowhere>
<urso0s$18tpq$1@dont-email.me> <87cysdqtu9.fsf@enoch.nodomain.nowhere>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Injection-Date: Sat, 2 Mar 2024 02:29:26 -0000 (UTC)
Injection-Info: dont-email.me; posting-host="83021536b0505deda7fdd938fb72990b";
logging-data="1482585"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX196HosuTALOJNVP8qa/V8YW73IIHFMC8RE="
User-Agent: Pan/0.139 (Sexual Chocolate; GIT bf56508
git://git.gnome.org/pan2)
Cancel-Lock: sha1:4WyhbOXN+0bGUFZULELyO056QF4=
 by: Lew Pitcher - Sat, 2 Mar 2024 02:29 UTC

On Fri, 01 Mar 2024 21:57:02 -0400, Mike Spencer wrote:

> Lew Pitcher <lew.pitcher@digitalfreehold.ca> writes:
>
>> On Thu, 29 Feb 2024 22:36:59 -0400, Mike Spencer wrote:
>>
>>> At times, using wicd, I disconnect from the router and reconnect via
>>> wi-fi, using a cell phone served by ISP "B" as an access point. Wicd
>>> replaces /etc/resolv.conf with one that references the nameservers of
>>> ISP "B". Apps such as a web browser and Usenet news proceed as
>>> expected after the change but sendmail fails to deliver messages to
>>> the remote smarthost.
>>>
>>> Restarting sendmail fixes this.
>> [snip]
>>
>> I think that you are trying to solve the wrong problem. The problem isn't
>> that sendmail caches the address of the DNS server, but that you are
>> using a DNS server who's address may change over time.
>>
>> You could just run a caching nameserver on your slackware box, and
>> resolve /all/ DNS queries against that server. This way, the DNS
>> server maintains a fixed address (perhaps, "localhost", in your case)
>> and sendmail doesn't have to fish about for DNS resolution.
>
> I never thought of that. The caching nameserver would have to be able
> to go to the right remote nameserver to update itself but that might
> be handled correctly.

Unless you configure it incorrectly, a caching nameserver "climbs the
tree" of domains for you, starting at the root servers, and working
its way up from the TLD to the full hostname. It definitely /would/
"go to the right remote nameserver" for any hostname available to
a public DNS query.

> One more thing to maintain kinda contravenes my preference for
> KISS but I'll have a look at that.

I guess that it depends on your definition of "simple". If "simple"
means finding some random hack to sendmail to make it stop caching
DNS query results, then, I guess, a sendmail hack satisfies your
KISS principle.

But, if the addition of a single, standard, low maintenance process
to your current configuration is simpler than a sendmail hack, then
a caching nameserver is the ticket.

I've run one for years, with no maintenance issues at all.

But, that's me. :-)

>> A caching DNS server adds very little to the system overhead, and,
>> beyond the initial setup, needs little or no maintenance. It gives
>> the added benefit of adding a bit more security to your DNS queries,
>> in that your ISP /does not/ handle the queries, /can't/ log or track
>> them, and /can't/ substitute their own sponsored/edited/redirected
>> answers.
>
> A potential problem, yeah. IIRC, I've only seen it happen twice, once
> using somebody's wi-fi where their router did DNS weirdly. I forget
> the details of the other case but it became publicly known and went
> away after public protest.

My GF has cable internet, and her ISP sometimes "redirects" her away
from the websites she asks for to sites that the ISP deems more
"suitable", using altered DNS reply values. But, then again, that ISP
also "injects" its own (sometimes sponsored) HTML into web pages she
views. She (thinks that she) has no choice but to tolerate this
corporate antisocial behaviour. :-(

Luck be with you.
--
Lew Pitcher
"In Skills We Trust"

Re: Sendmaail, resolv.conf, DNS

<urueib$1nsr6$3@dont-email.me>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2208&group=alt.os.linux.slackware#2208

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: ric...@example.invalid (Rich)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: Sat, 2 Mar 2024 05:47:55 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 35
Message-ID: <urueib$1nsr6$3@dont-email.me>
References: <878r32smno.fsf@enoch.nodomain.nowhere> <urri2f$11ui1$1@dont-email.me> <87le71quix.fsf@enoch.nodomain.nowhere>
Injection-Date: Sat, 2 Mar 2024 05:47:55 -0000 (UTC)
Injection-Info: dont-email.me; posting-host="d3ebb0a86cc1c2ad2af4dbd735b35c97";
logging-data="1831782"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+lK6cjgY/lWBLJGno3kEpb"
User-Agent: tin/2.6.1-20211226 ("Convalmore") (Linux/5.15.139 (x86_64))
Cancel-Lock: sha1:P/N0oxD8hJZjyCSX3Em/HncrS9w=
 by: Rich - Sat, 2 Mar 2024 05:47 UTC

Mike Spencer <mds@bogus.nodomain.nowhere> wrote:
>
> Rich <rich@example.invalid> writes:
>
>> Mike Spencer <mds@bogus.nodomain.nowhere> wrote:
>>
>>> It would be convenient to be able to query the sendmail daemon to see
>>> what it was using as nameservers and avoid a restart if one isn't
>>> needed.
>>
>> Not sure that is possible. Sendmail (and mail servers in general) are
>> going to assume stable, static IP values, and so it is very doubtful
>> there is any official way to ask the daemon what nameservers it is
>> using. Reason being that in a static environment, there's no need to
>> ever bother doing so.
>>
>> But, if the sendmail daemon's only task is to deliver outgoing mail to
>> a smarthost, what about configuring sendmail with the IP address of the
>> smart host? Then it won't need to do a DNS lookup to get the smart
>> host's IP, and changing resolv.conf won't matter to it. All that will
>> matter is that it can connect to that IP address via the current in use
>> network path.
>
> That's a good idea. I'm using the mailertable mechanism which, AIUI, is
> distinct from the smarthost one. But I could put the IP address in
> the mailertable & authinfo files, rebuild the corresponding .db files
> and see if the problem goes away. Don't have to mess with sendmail.cf.

Seems it is worth a try. It is likely your simplest item to try.

> My mail provider is a mom&pop ISP that seems to jockey IP addresses
> around from time to time but I can stay alert to that.

Yeah, you'll have to manually follow their changes if you go this
route.

Re: Sendmaail, resolv.conf, DNS

<uruf16$1nsr6$4@dont-email.me>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2209&group=alt.os.linux.slackware#2209

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: ric...@example.invalid (Rich)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: Sat, 2 Mar 2024 05:55:50 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 21
Message-ID: <uruf16$1nsr6$4@dont-email.me>
References: <878r32smno.fsf@enoch.nodomain.nowhere> <urso0s$18tpq$1@dont-email.me> <87cysdqtu9.fsf@enoch.nodomain.nowhere>
Injection-Date: Sat, 2 Mar 2024 05:55:50 -0000 (UTC)
Injection-Info: dont-email.me; posting-host="d3ebb0a86cc1c2ad2af4dbd735b35c97";
logging-data="1831782"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19lKjYArKOZq/thiaUgAcwf"
User-Agent: tin/2.6.1-20211226 ("Convalmore") (Linux/5.15.139 (x86_64))
Cancel-Lock: sha1:r1/OkGrAzivHBlVJQdNCGYnBnKA=
 by: Rich - Sat, 2 Mar 2024 05:55 UTC

Mike Spencer <mds@bogus.nodomain.nowhere> wrote:
>
> Lew Pitcher <lew.pitcher@digitalfreehold.ca> writes:
>> You could just run a caching nameserver on your slackware box, and
>> resolve /all/ DNS queries against that server. This way, the DNS
>> server maintains a fixed address (perhaps, "localhost", in your case)
>> and sendmail doesn't have to fish about for DNS resolution.
>
> I never thought of that. The caching nameserver would have to be able
> to go to the right remote nameserver to update itself but that might
> be handled correctly. One more thing to maintain kinda contravenes my
> preference for KISS but I'll have a look at that.

Slack 15 ships with bind config files suitable for running a caching
nameserver yourself. You likely only need to turn on /etc/rc.d/rc.bind
(make it executable) to gain a local caching nameserver on the next
boot.

If you don't want to reboot just to get named started, then just make
rc.bind executable and then launch it as "rc.bind start" while you are
root.

Re: Sendmaail, resolv.conf, DNS

<us01ll$226sm$1@dont-email.me>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2210&group=alt.os.linux.slackware#2210

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: mm+usene...@dorfdsl.de (Marco Moock)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: Sat, 2 Mar 2024 21:20:04 +0100
Organization: A noiseless patient Spider
Lines: 19
Message-ID: <us01ll$226sm$1@dont-email.me>
References: <878r32smno.fsf@enoch.nodomain.nowhere>
<urs39m$14o1e$3@dont-email.me>
<87h6hpqu9o.fsf@enoch.nodomain.nowhere>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Injection-Date: Sat, 2 Mar 2024 20:20:05 -0000 (UTC)
Injection-Info: dont-email.me; posting-host="86b1f5af9d6b577994ef444d9079a8f2";
logging-data="2169750"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19dlYogo3/mZKZ17AyQUbsp"
Cancel-Lock: sha1:9MfTryPHw4tbKQ789mUb/uqHv0c=
 by: Marco Moock - Sat, 2 Mar 2024 20:20 UTC

On 01.03.2024 um 21:47 Uhr Mike Spencer wrote:

> Hmm. I use wicd because NetworkManager demands a "tray" that isn't
> supported by my favored window manager (twm).

wicd is old-ass and no longer developed.
Networkmanager can be used without a GUI and without nm-applet.
You can manage it via nmcli and nm-tui.
I run it on servery that way and this is default on RHEL/Fedora.

> But wicd does seems to do the right thing about swapping the
> resolv.conf files back and forth. I'll have a closer look.

--
kind regards
Marco

Send spam to 1709326067muell@cartoonies.org

Re: Sendmaail, resolv.conf, DNS

<87v862pu0d.fsf@enoch.nodomain.nowhere>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2213&group=alt.os.linux.slackware#2213

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: mds...@bogus.nodomain.nowhere (Mike Spencer)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: 03 Mar 2024 23:15:30 -0400
Organization: Bridgewater Institute for Advanced Study - Blacksmith Shop
Lines: 18
Sender: mds@enoch.nodomain.nowhere
Message-ID: <87v862pu0d.fsf@enoch.nodomain.nowhere>
References: <878r32smno.fsf@enoch.nodomain.nowhere> <urso0s$18tpq$1@dont-email.me> <87cysdqtu9.fsf@enoch.nodomain.nowhere> <uruf16$1nsr6$4@dont-email.me>
Injection-Info: dont-email.me; posting-host="ffb7a5e0f47ac8405beb0adc52875681";
logging-data="3098459"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+qQ0/4oIPbLQZYQvcEvEddeZ1NZ+1CUls="
Cancel-Lock: sha1:RTHdJcUffeaoSI0stJWH55IMwQo=
X-Newsreader: Gnus v5.7/Emacs 20.7
X-Clacks-Overhead: 4GH GNU Terry Pratchett
 by: Mike Spencer - Mon, 4 Mar 2024 03:15 UTC

Rich <rich@example.invalid> writes:

> Slack 15 ships with bind config files suitable for running a caching
> nameserver yourself. You likely only need to turn on /etc/rc.d/rc.bind
> (make it executable) to gain a local caching nameserver on the next
> boot.
>
> If you don't want to reboot just to get named started, then just make
> rc.bind executable and then launch it as "rc.bind start" while you are
> root.

Interesting. More stuff I didn't know. When I get past the very
annoying episode of persistent vertigo, I'll have a look at that.

Tnx,
--
Mike Spencer Nova Scotia, Canada

Re: Sendmaail, resolv.conf, DNS

<slrnuucc94.dbl.zsd@x360.localdomain>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2214&group=alt.os.linux.slackware#2214

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: zsd...@jdvb.ca (Jim)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: Mon, 4 Mar 2024 16:37:55 -0400
Organization: A noiseless patient Spider
Lines: 27
Message-ID: <slrnuucc94.dbl.zsd@x360.localdomain>
References: <878r32smno.fsf@enoch.nodomain.nowhere>
<urs39m$14o1e$3@dont-email.me> <87h6hpqu9o.fsf@enoch.nodomain.nowhere>
Injection-Info: dont-email.me; posting-host="b54ee7d7a28100e893a8cedb7b8193d4";
logging-data="3514505"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX181sPfdTxY73MKTIxeGTZCb"
User-Agent: slrn/1.0.3 (Linux)
Cancel-Lock: sha1:wlnsEZ4lOb8wHl/645gWkq8hdzE=
 by: Jim - Mon, 4 Mar 2024 20:37 UTC

On 2024-03-01 at 21:47 AST, Mike Spencer <mds@bogus.nodomain.nowhere> wrote:
>
> Marco Moock <mm+usenet@dorfdsl.de> writes:
>
>> Am 29.02.2024 schrieb Mike Spencer <mds@bogus.nodomain.nowhere>:
>>
>>> Not limited to Slackware but as a long-time Slackware user, this group
>>> seems more like home to me...
>>
>> Your question fits in comp.mail.sendmail.
>
> Yeah. Hacking sendmail is really above my pay grade. :-) I'll go
> there if I get stuck.
>
>> IIRC for other operating systems a mechanism exists that automatically
>> reloads sendmail when the network changes (NetworkManager).
>> Maybe you can implement that in slackware too.
>
> Hmm. I use wicd because NetworkManager demands a "tray" that isn't
> supported by my favored window manager (twm). But wicd does seems to
> do the right thing about swapping the resolv.conf files back and
> forth. I'll have a closer look.

I use stalonetray to get a "tray" with fvwm. Perhaps twm could use that
somehow?

Jim

Re: Sendmaail, resolv.conf, DNS

<usd76d$17l7f$1@dont-email.me>

 copy mid

https://www.novabbs.com/computers/article-flat.php?id=2215&group=alt.os.linux.slackware#2215

 copy link   Newsgroups: alt.os.linux.slackware
Path: i2pn2.org!i2pn.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: jer...@example.invalid (Jerry Peters)
Newsgroups: alt.os.linux.slackware
Subject: Re: Sendmaail, resolv.conf, DNS
Date: Thu, 7 Mar 2024 20:14:05 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 32
Message-ID: <usd76d$17l7f$1@dont-email.me>
References: <878r32smno.fsf@enoch.nodomain.nowhere> <urs39m$14o1e$3@dont-email.me> <87h6hpqu9o.fsf@enoch.nodomain.nowhere> <slrnuucc94.dbl.zsd@x360.localdomain>
Injection-Date: Thu, 7 Mar 2024 20:14:05 -0000 (UTC)
Injection-Info: dont-email.me; posting-host="be22bc7bd5aaa5b9316ccf91a42fad97";
logging-data="1299695"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+U8RYHyU4LxiGmzbhiDTAqUZTX0gMc6Tw="
User-Agent: tin/2.4.5-20201224 ("Glen Albyn") (Linux/6.6.21 (x86_64))
Cancel-Lock: sha1:+VT7/gqnLpJ5CCyHe7mJ3fyTPqo=
 by: Jerry Peters - Thu, 7 Mar 2024 20:14 UTC

Jim <zsd@jdvb.ca> wrote:
> On 2024-03-01 at 21:47 AST, Mike Spencer <mds@bogus.nodomain.nowhere> wrote:
>>
>> Marco Moock <mm+usenet@dorfdsl.de> writes:
>>
>>> Am 29.02.2024 schrieb Mike Spencer <mds@bogus.nodomain.nowhere>:
>>>
>>>> Not limited to Slackware but as a long-time Slackware user, this group
>>>> seems more like home to me...
>>>
>>> Your question fits in comp.mail.sendmail.
>>
>> Yeah. Hacking sendmail is really above my pay grade. :-) I'll go
>> there if I get stuck.
>>
>>> IIRC for other operating systems a mechanism exists that automatically
>>> reloads sendmail when the network changes (NetworkManager).
>>> Maybe you can implement that in slackware too.
>>
>> Hmm. I use wicd because NetworkManager demands a "tray" that isn't
>> supported by my favored window manager (twm). But wicd does seems to
>> do the right thing about swapping the resolv.conf files back and
>> forth. I'll have a closer look.
>
> I use stalonetray to get a "tray" with fvwm. Perhaps twm could use that
> somehow?
>
> Jim

There's also wmsystemtray, which I use with fvwm.

Jerry

1
server_pubkey.txt

rocksolid light 0.9.7
clearnet tor