[pfx] Allow TLSv1 only for internal senders
Hi ! I setup my postfix for the clients to use only protocols > TLSv1 with smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1 smtpd_tls_protocols = !SSLv2,!SSLv3,!TLSv1 in main.cf but unfortunately i have a sender (its a printer) which is not capable for TLSv1.1 and up.. How can i manage to use TLSv1.1 and up from outside but allow TLSv1 from inside my network Ciao Gerd ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
On 2023-03-18 at 09:54:15 UTC-0400 (Sat, 18 Mar 2023 14:54:15 +0100) Gerd Hoerst via Postfix-users is rumored to have said: Hi ! I setup my postfix for the clients to use only protocols > TLSv1 with smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1 smtpd_tls_protocols = !SSLv2,!SSLv3,!TLSv1 in main.cf Why? but unfortunately i have a sender (its a printer) which is not capable for TLSv1.1 and up.. How can i manage to use TLSv1.1 and up from outside but allow TLSv1 from inside my network What do you believe to be the risk of allowing TLSv1.0 for SMTP? My understanding is that the marginal risks of TLSv1.0 are not relevant to SMTP. It is also inherently counter-productive to prohibit TLSv1.0 if you allow unencrypted SMTP as a fallback. -- Bill Cole b...@scconsult.com or billc...@apache.org (AKA @grumpybozo and many *@billmail.scconsult.com addresses) Not Currently Available For Hire ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
If you must (not necessariy a god idea), your options are:
- Multiple Posifix instances on different IP addresses. Each instance
has its own main.cf and master.cf.
- Single Postfix instance with different smtpd configurations in
master.cf on different server IP addresses, using main.cf only for
common settings.
/etc/postfix.master.cf:
# =
# service type private unpriv chroot wakeup maxproc command
# (yes) (yes) (yes) (never) (100)
# =
# SMTP service for internal clients)
1.2.3.4:smtp inet n - n - - smtpd
-o { parameter = value }
...
# SMTP service for xternal clients
1.2.3.5:smtp inet n - n - - smtpd
-o { parameter = value }
...
This is manageable when the differences ar small.
Wietse
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[pfx] Re: Allow TLSv1 only for internal senders
Hi ! I read a tutorial to harden postfix and there they trew out TLSv1 Ciao Gerd Am 18.03.2023 um 16:07 schrieb Bill Cole via Postfix-users: On 2023-03-18 at 09:54:15 UTC-0400 (Sat, 18 Mar 2023 14:54:15 +0100) Gerd Hoerst via Postfix-users is rumored to have said: Hi ! I setup my postfix for the clients to use only protocols > TLSv1 with smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1 smtpd_tls_protocols = !SSLv2,!SSLv3,!TLSv1 in main.cf Why? but unfortunately i have a sender (its a printer) which is not capable for TLSv1.1 and up.. How can i manage to use TLSv1.1 and up from outside but allow TLSv1 from inside my network What do you believe to be the risk of allowing TLSv1.0 for SMTP? My understanding is that the marginal risks of TLSv1.0 are not relevant to SMTP. It is also inherently counter-productive to prohibit TLSv1.0 if you allow unencrypted SMTP as a fallback. ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
Gerd Hoerst via Postfix-users skrev den 2023-03-18 14:54: smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1 smtpd_tls_protocols = !SSLv2,!SSLv3,!TLSv1 in main.cf in main.cf put a # in this lines, so its default from postconf -d but unfortunately i have a sender (its a printer) which is not capable for TLSv1.1 and up.. add in master.cf -o smtpd_tls_mandatory_protocols=!SSLv2,!SSLv3,!TLSv1 -o smtpd_tls_protocols=!SSLv2,!SSLv3,!TLSv1 so only port 465, 587 have this, but you should keep defaults this will do what you want, but imho why not keep all tls for all ? How can i manage to use TLSv1.1 and up from outside but allow TLSv1 from inside my network tlsv1 is less weak then tlsv1.1 others will comment now I am sure :) ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
Gerd Hoerst via Postfix-users skrev den 2023-03-18 14:54: smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1 smtpd_tls_protocols = !SSLv2,!SSLv3,!TLSv1 in main.cf in main.cf put a # in this lines, so its default from postconf -d but unfortunately i have a sender (its a printer) which is not capable for TLSv1.1 and up.. On 18.03.23 19:35, Benny Pedersen via Postfix-users wrote: add in master.cf -o smtpd_tls_mandatory_protocols=!SSLv2,!SSLv3,!TLSv1 -o smtpd_tls_protocols=!SSLv2,!SSLv3,!TLSv1 so only port 465, 587 have this, but you should keep defaults Usually, smtpd_tls_mandatory_protocols are user on 465 and 587, while smtpd_tls_protocols is used on port 25. So you only need to define them properly in main.cf, unless you play with different settings on different ports. I would generally allow the printer to use port 25. -- Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. I drive way too fast to worry about cholesterol. ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
On Sat, Mar 18, 2023 at 07:32:18PM +0100, Gerd Hoerst via Postfix-users wrote: > I read a tutorial to harden postfix and there they trew out TLSv1 The tutorial is mostly misguided. Though in practice, TLS 1.0 is increasingly rare on the public Internet, so the damage from disabling it is fairly low. So your server will score more points in a fashion show of modern cryptographic prowess if TLS 1.0 is disabled. You now have a choice between being fashionable, and being interoperable with a dwindling number of unfashionable systems. The latter also makes a non-conformist statement I guess. Choose your crowd. -- Viktor. ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
Dnia 18.03.2023 o godz. 14:54:15 Gerd Hoerst via Postfix-users pisze: > I setup my postfix for the clients to use only protocols > TLSv1 with > > smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1 > smtpd_tls_protocols = !SSLv2,!SSLv3,!TLSv1 While the former makes some sense (requiring TLS>=1.1 for mail *submission* from your users) - most mail clients are able to conform to this - the latter (requiring TLS>=1.1 for *incoming* mail on port 25) does not. Don't do it. -- Regards, Jaroslaw Rafa r...@rafa.eu.org -- "In a million years, when kids go to school, they're gonna know: once there was a Hushpuppy, and she lived with her daddy in the Bathtub." ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
Jaroslaw Rafa wrote in <20230318191215.gb30...@rafa.eu.org>: |Dnia 18.03.2023 o godz. 14:54:15 Gerd Hoerst via Postfix-users pisze: |> I setup my postfix for the clients to use only protocols > TLSv1 with |> |> smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1 |> smtpd_tls_protocols = !SSLv2,!SSLv3,!TLSv1 | |While the former makes some sense (requiring TLS>=1.1 for mail *submission* |from your users) - most mail clients are able to conform to this - \ |the latter |(requiring TLS>=1.1 for *incoming* mail on port 25) does not. Don't do it. I still have no problems with smtpd_tls_mandatory_protocols = >=TLSv1.2 smtpd_tls_protocols = $smtpd_tls_mandatory_protocols # super modern, forward secrecy TLSv1.2 / TLSv1.3 selection.. tls_high_cipherlist = EECDH+AESGCM:EECDH+AES256:EDH+AESGCM:CHACHA20 smtpd_tls_mandatory_ciphers = high Neither for lighttpd nor for postfix. --steffen | |Der Kragenbaer,The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt) ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
Dnia 18.03.2023 o godz. 21:08:17 Steffen Nurpmeso via Postfix-users pisze: > I still have no problems with > > smtpd_tls_mandatory_protocols = >=TLSv1.2 > smtpd_tls_protocols = $smtpd_tls_mandatory_protocols > # super modern, forward secrecy TLSv1.2 / TLSv1.3 selection.. > tls_high_cipherlist = EECDH+AESGCM:EECDH+AES256:EDH+AESGCM:CHACHA20 > smtpd_tls_mandatory_ciphers = high > > Neither for lighttpd nor for postfix. First, we should not mix HTTP(S) with SMTP, these are two completely different things. While as strict TLS security as possible in the web browsing is essential (think about various highly private data you are transmitting eg. when doing online shopping or banking), it has much less meaning in email, due to nature of TLS in email being opportunistic, that means, if servers can't negotiate TLS connection, they fall back to plaintext (unencrypted), because mail must be delivered anyway. As mail can go through various intermediate servers over which you have no control, and can be stored on them for a period of time over which you have no control, if anything highly sensitive is sent via email, it should be end-to-end encrypted anyway, using applications like gpg or similar, and not rely on transport encryption. Second, most web browsers nowadays (as well as mail clients) support TLS v1.2 since long time, so it's of course very little probability that someone who uses so outdated browser that it doesn't support TLS v1.2 will try to access your website, *and*: a) either that person will complain to you, or b) you will notice it in your httpd logs. Third, there are still quite a few mail *servers* that don't support TLS v1.2. In that case, they will fall back to plaintext when sending mail to your server. Do you analyze your logs for such cases? When I occasionally browse my Postfix logs, I notice one particular server (from which I receive mail quite often) that can negotiate only TLS v1 connection with my server. So if I would require TLS>=1.2 on my server, that server would fall back to plaintext to send mail to me. I think that TLS v1 is still better security than no encryption at all ;) -- Regards, Jaroslaw Rafa r...@rafa.eu.org -- "In a million years, when kids go to school, they're gonna know: once there was a Hushpuppy, and she lived with her daddy in the Bathtub." ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
On 19/03/23 09:08, Steffen Nurpmeso via Postfix-users wrote: I still have no problems with smtpd_tls_mandatory_protocols = >=TLSv1.2 This is fine, so long as you don't have a user that can't support at least TLSv1.2 that needs to use submission. smtpd_tls_protocols = $smtpd_tls_mandatory_protocols This will simply result in clients that can't support at least TLSv1.2 connecting in plain text instead. So rather than having (arguably not so) poor encryption for those client you would rather have no encryption at all? This does not make any sense. # super modern, forward secrecy TLSv1.2 / TLSv1.3 selection.. tls_high_cipherlist = EECDH+AESGCM:EECDH+AES256:EDH+AESGCM:CHACHA20 I would avoid messing with this setting unless you really understand what you are doing, and even then it's not a very good idea. You could end up causing some clients to be unable to establish a connection or on the flip side you could inadvertently be enabling a cipher that ends up becoming vulnerable in the future unless you stay on top of this setting and remove it from the list. Note that the default for this setting is taken from openssl so when a vulnerability does get found in a cipher you will get an update to openssl from your OS vendor which will remove that cipher from the list, unless you do something like override it like you are doing above. smtpd_tls_mandatory_ciphers = high This is fine. Peter ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
On 19/03/23 02:54, Gerd Hoerst via Postfix-users wrote: I setup my postfix for the clients to use only protocols > TLSv1 with smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1 A better way to do this is: smtpd_tls_protocols = >=TLSv1.1 smtpd_tls_protocols = !SSLv2,!SSLv3,!TLSv1 Don't do this! All you will accomplish is to force clients that don't support at least TLSv1.1 to connect in plain text instead. No encryption is never better than (arguably not very) weak encryption. in main.cf but unfortunately i have a sender (its a printer) which is not capable for TLSv1.1 and up.. As others have pointed out, TLSv1.0 is not that bad for smtp. Others have posted a solution for this, but honestly I would just allow >=TLSv1 and not worry about it. Peter ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
On 19/03/23 07:44, Matus UHLAR - fantomas via Postfix-users wrote: I would generally allow the printer to use port 25. Port 25 is not a submission port and should not be used as such. Keep your submission separate from your MX traffic and you will avoid a whole heap of issues down the road. If you want a separate port for the printer then just create one in master.cf: 10465 inet n - n - - smtpd -o syslog_name=postfix/10465 -o smtpd_tls_wrappermode=yes -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes -o smtpd_reject_unlisted_recipient=no -o smtpd_recipient_restrictions=$mua_recipient_restrictions -o milter_macro_daemon_name=ORIGINATING ...or similar for a submission (non-wrappermode) port. Peter ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
Jaroslaw Rafa wrote in <20230318203334.ga31...@rafa.eu.org>: |Dnia 18.03.2023 o godz. 21:08:17 Steffen Nurpmeso via Postfix-users pisze: |> I still have no problems with |> |> smtpd_tls_mandatory_protocols = >=TLSv1.2 |> smtpd_tls_protocols = $smtpd_tls_mandatory_protocols |> # super modern, forward secrecy TLSv1.2 / TLSv1.3 selection.. |> tls_high_cipherlist = EECDH+AESGCM:EECDH+AES256:EDH+AESGCM:CHACHA20 |> smtpd_tls_mandatory_ciphers = high |> |> Neither for lighttpd nor for postfix. | |First, we should not mix HTTP(S) with SMTP, these are two completely |different things. While as strict TLS security as possible in the web |browsing is essential (think about various highly private data you are |transmitting eg. when doing online shopping or banking), it has much less Eh, no. I do not do either. (Granted i use PayPal one, two times a month, but my bank account is not online-enabled.) I _never_ shopped online. This destroys local pharmacies, shops, small (hopefully) good jobs that sometimes exist for centuries. Western world cities have become faceless culture-free concrete djungles with McDonald's smell for kilometres. No. |meaning in email, due to nature of TLS in email being opportunistic, that |means, if servers can't negotiate TLS connection, they fall back to |plaintext (unencrypted), because mail must be delivered anyway. | |As mail can go through various intermediate servers over which you have no |control, and can be stored on them for a period of time over which you have |no control, if anything highly sensitive is sent via email, it should be |end-to-end encrypted anyway, using applications like gpg or similar, \ |and not |rely on transport encryption. | |Second, most web browsers nowadays (as well as mail clients) support TLS |v1.2 since long time, so it's of course very little probability that \ |someone |who uses so outdated browser that it doesn't support TLS v1.2 will try to |access your website, *and*: a) either that person will complain to you, or |b) you will notice it in your httpd logs. Sorry i do not understand a word. Long time TLSv1.2, yes. |Third, there are still quite a few mail *servers* that don't support TLS |v1.2. In that case, they will fall back to plaintext when sending mail to |your server. Do you analyze your logs for such cases? I have looked once i switched. I noted a rush of lower connections once i posted the above last. Even the GNU server now uses more modern things, as it gets through. I do not know one. |When I occasionally browse my Postfix logs, I notice one particular server |(from which I receive mail quite often) that can negotiate only TLS v1 |connection with my server. So if I would require TLS>=1.2 on my server, \ |that |server would fall back to plaintext to send mail to me. I think that TLS v1 |is still better security than no encryption at all ;) For _me_ it works in practice and there is no fallout. I get anything i need / expect. If you have to take care for some elder servers then this is surely a problem you have to solve, especially if it is your business. In general people update OpenSSL / crypto library of choice, aka install their distribution's security updates, in which case all is well out of the box (and likely would be for some years). The only problem i currently have is Mar 18 22:24:53 postfix/smtpd[26025]: warning: run-time library vs. compile-time header version mismatch: OpenSSL 3.1.0 may not be compatible with OpenSSL 3.0.0 i hope AlpineLinux recompiles some OpenSSL-linked software so we get rid of that. --steffen | |Der Kragenbaer,The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt) ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Fwd: Re: Re: Allow TLSv1 only for internal senders
--- Forwarded from Steffen Nurpmeso --- Date: Sun, 19 Mar 2023 00:06:13 +0100 Author: Steffen Nurpmeso From: Steffen Nurpmeso To: Peter Subject: Re: [pfx] Re: Allow TLSv1 only for internal senders Message-ID: <20230318230613.c9hc0%stef...@sdaoden.eu> OpenPGP: id=EE19E1C1F2F7054F8D3954D8308964B51883A0DD; url=https://ftp.sdaoden.eu/steffen.asc; preference=signencrypt Peter wrote in <29591811-f04e-b667-d5df-3e3223e7d...@pajamian.dhs.org>: |On 19/03/23 09:08, Steffen Nurpmeso via Postfix-users wrote: |> I still have no problems with |> |>smtpd_tls_mandatory_protocols = >=TLSv1.2 | |This is fine, so long as you don't have a user that can't support at |least TLSv1.2 that needs to use submission. Submission via VPN (without starttls / TLS). |>smtpd_tls_protocols = $smtpd_tls_mandatory_protocols | |This will simply result in clients that can't support at least TLSv1.2 |connecting in plain text instead. So rather than having (arguably not |so) poor encryption for those client you would rather have no encryption |at all? This does not make any sense. There is none. I have looked, there is only a single server of value, and it does not even try starttls. (And he won the USENIX Flame award.) |># super modern, forward secrecy TLSv1.2 / TLSv1.3 selection.. |>tls_high_cipherlist = EECDH+AESGCM:EECDH+AES256:EDH+AESGCM:CHACHA20 | |I would avoid messing with this setting unless you really understand |what you are doing, and even then it's not a very good idea. You could |end up causing some clients to be unable to establish a connection or on |the flip side you could inadvertently be enabling a cipher that ends up |becoming vulnerable in the future unless you stay on top of this setting |and remove it from the list. Note that the default for this setting is |taken from openssl so when a vulnerability does get found in a cipher |you will get an update to openssl from your OS vendor which will remove |that cipher from the list, unless you do something like override it like |you are doing above. | |>smtpd_tls_mandatory_ciphers = high | |This is fine. --steffen | |Der Kragenbaer,The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt) -- End forward <20230318230613.c9hc0%stef...@sdaoden.eu> --steffen | |Der Kragenbaer,The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt) ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
[pfx] Re: Allow TLSv1 only for internal senders
Dnia 18.03.2023 o godz. 23:54:28 Steffen Nurpmeso via Postfix-users pisze: > Eh, no. I do not do either. (Granted i use PayPal one, two times > a month, but my bank account is not online-enabled.) > I _never_ shopped online. This destroys local pharmacies, shops, > small (hopefully) good jobs that sometimes exist for centuries. > Western world cities have become faceless culture-free concrete > djungles with McDonald's smell for kilometres. No. Well... if you could just buy the things you *absolutely need* anywhere else than online... if it were so simple... Sorry, but this is the reality, at least where I live. The local shops have already been by large part destroyed by online shopping. It's too late. You can't buy anything in a local shop if the shop doesn't sell it. Nowadays only the most popular and mass-bought items are available in physical shops. If you need anything that is a bit less popular, you *have* to buy it online. Sorry, that's it. Two examples from last weeks: OMTP to CTIA headphone adapter for a mobile phone? A replacement battery for a used laptop I just bought (in a physical shop btw.)? No chance to get anywhere else than online. And I live in a large city. What should people in rural areas say? And as for the banking, I never understand the people who don't do online banking. You have to constantly pay for something - electricity, Internet, rent, insurance, telephone etc. - all this happens by transferring money to some account. There's a dozen of these payments each month. Do you really want to go to the bank (or to a post office), stand there in a long line to pay for this in cash or fill in a money transfer form on paper and give it to the clerk, instead of doing it conveniently from your computer whenever you have time? > |Second, most web browsers nowadays (as well as mail clients) support TLS > |v1.2 since long time, so it's of course very little probability that \ > |someone > |who uses so outdated browser that it doesn't support TLS v1.2 will try to > |access your website, *and*: a) either that person will complain to you, or > |b) you will notice it in your httpd logs. > > Sorry i do not understand a word. Long time TLSv1.2, yes. I mean, if your website requires TLSv1.2 (because you mentioned lighthttpd, I assume you run some website), for you to notice any problems with it, the following conditions must be met: a) there is a person who is interested in accessing your website and at the same time uses a very outdated browser that doesn't suppport TLSv1.2 and either b) that person complains to you (eg. via e-mail) that he/she can't connect or c) you will notice browsing your httpd logs that some client was unable to connect due to incompatible TLS version. Only if a) and b) or a) and c) are met simultaneously, you will notice that there are any problems. There is very little probability that this will happen. Even a) alone isn't very probable, because there's a small number of people using so old browsers, and how many of them are interested in your particular website? But even if a) alone occurs, you will not notice any problems until b) or c) occurs as well. So it is quite obvious that you don't notice any problems. > For _me_ it works in practice and there is no fallout. I get > anything i need / expect. If you have to take care for some elder > servers then this is surely a problem you have to solve, > especially if it is your business. I'm not talking about any server that I take care for. I'm talking about a server of a company from which I receive emails, as their customer. Their server can negotiate only TLSv1 with my server. Anyway, it's better than if they would send their mail unencrypted. And they would, if I set *my* server to TLSv1.2 minimum (which I don't do). -- Regards, Jaroslaw Rafa r...@rafa.eu.org -- "In a million years, when kids go to school, they're gonna know: once there was a Hushpuppy, and she lived with her daddy in the Bathtub." ___ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
