nixos/machines/nyarlathotep/configuration.nix

@@ -15,10 +15,12 @@
     stalwartAdminHash = "$argon2i$v=19$m=4096,t=3,p=1$d0hYOTkzclpzSmFTZUplWnhVeWE$I7q9uB19RWL0oZKaPlMPSlGfFp6FQ/vrx80FFKCsalg";
     domains = [
       # lists.mathebau.de is forwarded to another VM and does not need to be listed here.
-      {
+      /*
+        {
         domain = "matheball.de";
         allowlistPass = config.sops.secrets."allowlistPass/matheball".path;
       }
+      */
       {
         domain = "mathebau.de";
         allowlistPass = config.sops.secrets."allowlistPass/mathebau".path;
@@ -73,6 +75,18 @@
       group = "stalwart-mail";
       mode = "0440";
     };
+    "dkim_rsa" = {
+      sopsFile = ./dkim.keys.yaml;
+      owner = "stalwart-mail";
+      group = "stalwart-mail";
+      mode = "0440";
+    };
+    "dkim_ed25519" = {
+      sopsFile = ./dkim.keys.yaml;
+      owner = "stalwart-mail";
+      group = "stalwart-mail";
+      mode = "0440";
+    };
     # password for https://stalw.art/docs/auth/authorization/administrator/#fallback-administrator encoded to be supplied in the basic auth header
     stalwartAdmin = {
       sopsFile = ./stalwartAdmin.secrets.yaml;

nixos/machines/nyarlathotep/dkim.keys.yaml

@@ -0,0 +1,40 @@
+dkim_rsa: ENC[AES256_GCM,data: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,iv:QbZVXp5FQhmYZvXxXNxWKrNm5GqM+2P3a5pPk499mlc=,tag:F+KNoPRnoLLhOpEj6Czj6Q==,type:str]
+dkim_ed25519: ENC[AES256_GCM,data:cZHm7bVpQ/VhYLt2CnNk9364k+J5ybgSLrR7Vm1GsCU6JcAvHl8Y5R7mqwgS+gTnHX7K02GuIGXa8909/aEotE0ZMY5irKJ25SGJqTaqQafbiMOz65CRQh5trtcMBF4s4wRYOkDGgz09KkELbkDHyQZFcrGqvgM=,iv:p9ROj/epqR3xtrimXF1onJJHH9JUqNG9z1MxKVu9uPg=,tag:m53rXkcu+ernS5JX+k8YcA==,type:str]
+sops:
+    kms: []
+    gcp_kms: []
+    azure_kv: []
+    hc_vault: []
+    age:
+        - recipient: age1rasjnr2tlv9y70sj0z0hwpgpxdc974wzg5umtx2pnc6z0p05u3js6r8sln
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSB6VnhvWHdsZWNHemlueFo4
+            L0xCTGp4NlRuU3YwRWJiSHFBbmtURTNMQkVRCnlSbFc0Q2xINjRvU2tQeStQc1U5
+            VElxcTVuNm9MUm01RkpGYytrYWg0czgKLS0tIHZqUWhkMGRNNjJvUTQrOHBpZXVS
+            NlpjeDQxbVZIRHFCcmNtT1JSVHp1K2sKSNcC0fcOar/KKzs1twaozB8wfdFT9OdB
+            4quV/ycNpJpfs6+2r0RTLBxYFyusybu1swosAni+PJsRXS82+PTXHQ==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1epz92k2rkp43hkrg3u0jgkzhnkwx8y43kag7rvfzwl9wcddelvusyetxl7
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBsUTUzYzZuMkYvcTlrUmRK
+            aStnak5IWitFUSt0eVBQOHIzcTlrMFRFTjA4CmlYUTdobXFUK2tYMWtFekNqNnhp
+            R2RRRFdHc1p6bFVjYU9lbTRBeEM3Y2sKLS0tIHdsRW1wR25pVkZIYU1yMm9sQXpr
+            NFhiN0pyaHVWT1h5eVFXMWZDb0sxUGMKIVkYYheD8F9aaAyCA+m9ZGlV8vKbAW4r
+            H6FUe+ats30abxoYfHZfMJv17BxJtpodksSxWjnPYm0dfRf/EF/vSQ==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1ktwclxa640l89le6yecm8v2z6hmwr4lusd6x9gyzamhv57887szqtqp59a
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBvU3NzY0Uxc0NhY2xJZyti
+            TCtTS1crV3hzMXZNV3k4cm0zUFNuY2tBL0dNCnNpYytoaUI1eERhdG1PUlZ2eE5C
+            R2UrVlBwcXR2L1VNR3RJL1lEQmlTSDgKLS0tIFJyLzhZeG5zejFmL2VkYy8xVEM1
+            U3QwOXlRdU8yd3ozL2hUVzRXNGE0bDQKT7SLAqICsbFmRUF+3s2avpBt0dLUbHLX
+            AgQzx5v6GpMMNwCkCrOnpFX6al7zkRSYHe7hbn03BBORz9mPHek5ew==
+            -----END AGE ENCRYPTED FILE-----
+    lastmodified: "2025-03-02T07:58:00Z"
+    mac: ENC[AES256_GCM,data:OvERjDFfHTJbTfwq9BmXBQy6pjeyIhao6zP4we0KeYL3skbw4+aaMixjUFzjauby0C7nJjEPBSk6pwK3lN+rScS5g7J8tTNtmhfEDQbfsS5zNDKzIQjYxbUbDr2cTPWwCA73gRGMwLbyNvdfuEp46jNV8OJ8km/y2nyG9lDcBb4=,iv:0RSU2MdZWiYEapwXGzevP9/vc/Sk1MS6a0MnCRQyIs8=,tag:vvngXS2IRzH999yzo4JyFQ==,type:str]
+    pgp: []
+    unencrypted_suffix: _unencrypted
+    version: 3.9.4

nixos/modules/mail.nix

@@ -65,7 +65,7 @@ in {
         openFirewall = true;
         settings = {
           server = {
-            lookup.default.hostname = "fb04184.mathematik.tu-darmstadt.de"; # Because the DNS PTR of 130.83.2.184 is this and this should be used in SMTP EHLO.
+            hostname = "fb04184.mathematik.tu-darmstadt.de"; # Because the DNS PTR of 130.83.2.184 is this and this should be used in SMTP EHLO.
             listener = {
               "smtp" = {
                 bind = ["[::]:25"];
@@ -82,7 +82,7 @@ in {
                 tls.implicit = true;
               };
               "management" = {
-                # Cthulhu forwards requests for http://fb04184.mathematik.tu-darmstadt.de/.well-known/acme-challenge/ http://imap.mathebau.de/.well-known/acme-challenge/ and http://smtp.mathebau.de/.well-known/acme-challenge/
+                # Cthulhu forwards requests for http://fb04184.mathematik.tu-darmstadt.de/.well-known/acme-challenge/ http://imap.mathebau.de/.well-known/acme-challenge/ and http://smtp.mathebau.de/.well-known/acme-challenge/ and http://mathebau.de/.well-known/acme-challenge/
                 # for TLS certificate challenge validation
                 # whereas the rest of the management interface is not available publically.
                 # It can be reached via SSH and portforwarding.
@@ -95,19 +95,28 @@ in {
             directory = "https://acme-v02.api.letsencrypt.org/directory"; # This setting is necessary for this block to be activated
             challenge = "http-01";
             contact = ["root@mathebau.de"];
-            domains = ["fb04184.mathematik.tu-darmstadt.de" "imap.mathebau.de" "smtp.mathebau.de"];
+            domains = ["fb04184.mathematik.tu-darmstadt.de" "imap.mathebau.de" "smtp.mathebau.de" "mathebau.de"];
             default = true;
           };
           # Reevaluate after DKIM and DMARC deployment
           spam.header.is-spam = "Dummyheader"; # disable moving to spam which would conflict with forwarding
           auth = {
-            # TODO check if HRZ conforms to these standards and we can validate them strictly
+            # TODO check if HRZ and our own VMs conform to these standards and we can validate them strictly
             dkim.verify = "relaxed";
             arc.verify = "relaxed";
             dmarc.verify = "relaxed";
             iprev.verify = "relaxed";
             spf.verify.ehlo = "relaxed";
             spf.verify.mail-from = "relaxed";
+
+            # Sign *our* outgoing mails with the configured signatures.
+            dkim.sign = [
+              {
+                "if" = "is_local_domain('', sender_domain) || sender_domain == 'lists.mathebau.de'";
+                "then" = "['rsa-' + sender_domain, 'ed25519-' + sender_domain]";
+              }
+              {"else" = false;}
+            ];
           };
 
           # Forward outgoing mail to HRZ or mail VMs.
@@ -131,36 +140,61 @@ in {
               starttls = "optional"; # e.g. Lobon does not offer starttls
             };
           };
-          remote."hrz" = {
+          remote = {
-            address = "mailout.hrz.tu-darmstadt.de";
+            "hrz" = {
-            port = 25;
+              address = "mailout.hrz.tu-darmstadt.de";
-            protocol = "smtp";
+              port = 25;
-            tls.implicit = false; # Don't assume TLS on this port but use STARTTLS
+              protocol = "smtp";
-          };
+              tls.implicit = false; # Don't assume TLS on this port but use STARTTLS
-          remote."mailman" = {
+            };
-            address = "lobon.mathebau.de"; # must be created in DNS as a MX record because this field does not accept ip addresses.
+            "mailman" = {
-            port = 25;
+              address = "lobon.mathebau.de"; # must be created in DNS as a MX record because this field does not accept ip addresses.
-            protocol = "smtp";
+              port = 25;
-            tls.implicit = false; # Don't assume TLS on this port but use STARTTLS
+              protocol = "smtp";
+              tls.implicit = false; # Don't assume TLS on this port but use STARTTLS
+            };
           };
 
-          session.rcpt = {
+          session = {
-            # In order to accept mail that we only forward
+            ehlo.require = [
-            # without having to generate an account.
-            # Invalid addresses are filtered by DFN beforehand.
-            catch-all = true;
-            relay = [
               {
-                "if" = "!is_empty(authenticated_as) || rcpt_domain == 'lists.mathebau.de' || starts_with(remote_ip, '192.168.0.')"; #TODO restrict trust by IP
+                "if" = "starts_with(remote_ip, '192.168.0.')"; #TODO setup vms properly
-                "then" = true;
+                "then" = false;
               }
-              {"else" = false;}
+              {"else" = true;}
             ];
+            ehlo.reject-non-fqdn = [
+              {
+                "if" = "starts_with(remote_ip, '192.168.0.')"; #TODO setup vms properly
+                "then" = false;
+              }
+              {"else" = true;}
+            ];
+
+            rcpt = {
+              # In order to accept mail that we only forward
+              # without having to generate an account.
+              # Invalid addresses are filtered by DFN beforehand.
+              # See also https://stalw.art/docs/smtp/inbound/rcpt/#catch-all-addresses
+              catch-all = true;
+              relay = [
+                {
+                  "if" = "!is_empty(authenticated_as) || rcpt_domain == 'lists.mathebau.de' || starts_with(remote_ip, '192.168.0.')"; #TODO restrict trust by IP
+                  "then" = true;
+                }
+                {"else" = false;}
+              ];
+              # The sieve script only handles the last RCPT TO command (https://stalw.art/docs/sieve/variables).
+              # Since we want it to run for every recipient, we need to accept them one at a time. :-(
+              # This setting throws a temporary error for the second RCPT TO command after which the HRZ retries in a new connection.
+              max-recipients = 1;
+            };
+            data.script = "'redirects'";
           };
 
           # Stalwart gets its configuration from two places: A TOML configuration file that we control in this module
           # and from a database that can be configured from web management interface or via Rest API.
-          # We here define what comes from the TOML-file and especially add "sieve.trusted.scripts.*" to the default ones
+          # We here define what comes from the TOML-file and especially add "sieve.trusted.*" to the default ones
           # because only TOML-based keys may use macros to load files from disk.
           # We want this to be able to load our sieve-script for mail forwarding.
           # See https://stalw.art/docs/configuration/overview/#local-and-database-settings for more details.
@@ -181,9 +215,47 @@ in {
               "lookup.default.hostname"
               "certificate.*"
             ] # the default ones
-            ++ ["sieve.trusted.scripts.*"]; #for macros to be able to include our redirection script
+            ++ ["sieve.trusted.*"]; #for macros to be able to include our redirection script
-          sieve.trusted.scripts.redirects.contents = "%{file:/tmp/virt_aliases}%"; # generated redirect script
+          sieve.trusted = {
-          session.data.script = "'redirects'";
+            scripts.redirects.contents = "%{file:/tmp/virt_aliases}%"; # generated redirect script
+            return-path = "sender"; # set the outgoing MAIL FROM to the original sender as specified in the incoming MAIL FROM.
+
+            # If we are the sender, we sign the message with DKIM. Else we leave it alone.
+            sign = [
+              {
+                "if" = "is_local_domain('', sender_domain) || sender_domain == 'lists.mathebau.de'";
+                "then" = "['rsa-' + sender_domain, 'ed25519-' + sender_domain]";
+              }
+              {"else" = false;}
+            ];
+            limits = {
+              redirects = 50;
+              out-messages = 50;
+            };
+          };
+          # See https://stalw.art/docs/smtp/authentication/dkim/sign
+          # We need two blocks per domain because the domain setting in the blocks does not accept variables like `sender_domain`.
+          signature = let
+            signatureTemplate = domain: {
+              "rsa-${domain}" = {
+                private-key = "%{file:/run/secrets/dkim_rsa}%";
+                domain = "${domain}";
+                selector = "rsa-default";
+                headers = ["From" "To" "Cc" "Date" "Subject" "Message-ID" "Organization" "MIME-Version" "Content-Type" "In-Reply-To" "References" "List-Id" "User-Agent" "Thread-Topic" "Thread-Index"];
+                algorithm = "rsa-sha256";
+                canonicalization = "relaxed/relaxed";
+              };
+              "ed25519-${domain}" = {
+                private-key = "%{file:/run/secrets/dkim_ed25519}%";
+                domain = "${domain}";
+                selector = "ed-default";
+                headers = ["From" "To" "Cc" "Date" "Subject" "Message-ID" "Organization" "MIME-Version" "Content-Type" "In-Reply-To" "References" "List-Id" "User-Agent" "Thread-Topic" "Thread-Index"];
+                algorithm = "ed25519-sha256";
+                canonicalization = "relaxed/relaxed";
+              };
+            };
+          in
+            map signatureTemplate (["lists.mathebau.de"] ++ (map ({domain, ...}: domain) cfg.domains));
 
           authentication.fallback-admin = {
             user = "admin";
@@ -229,7 +301,8 @@ in {
               echo "process ${domain}"
               # This line gets the available mailboxes from stalwart's Rest API, searches for their addresses and collects them to a file for submission.
               # The regex searches for alphanumerics combined with some special characters as local paths and the right domain.
-              ${pkgs.curl}/bin/curl -s --header "authorization: Basic $(<${cfg.stalwartAdmin})" http://localhost/api/principal | ${pkgs.gnugrep}/bin/grep -o -e "[A-Za-z0-9.!#\$%&'*+-/=?^_{|}~]*@${domain}" | tee /tmp/addresses
+              # Exclude @domain.tld which is not a valid mail address but used for catch-all accounts.
+              ${pkgs.curl}/bin/curl -s --header "authorization: Basic $(<${cfg.stalwartAdmin})" http://localhost/api/principal | ${pkgs.gnugrep}/bin/grep -o -e "[A-Za-z0-9.!#\$%&'*+-/=?^_{|}~]*@${domain}" | grep -v "@${domain}" | tee /tmp/addresses
               # This line searches for available redirects and adds them to the submission file.
               ${pkgs.gnugrep}/bin/grep -o -e "[A-Za-z0-9.!#\$%&'*+-/=?^_{|}~]*@${domain}" /tmp/virt_aliases >> /tmp/addresses # This doesn't catch all RFC conform local parts. Improve if you need.
               # Post local-parts to HRZ, see https://www-cgi.hrz.tu-darmstadt.de/mail/index.php?bereich=whitelist_upload
@@ -267,6 +340,7 @@ in {
         "stalwart-mail" = {
           restartTriggers = lib.attrsets.mapAttrsToList (_: aliaslist: aliaslist.sopsFile) config.sops.secrets; # restart if secrets, especially alias files, have changed.
           serviceConfig.PrivateTmp = lib.mkForce false; # enable access to generated Sieve script
+          serviceConfig.ProtectSystem = lib.mkForce "full"; # "strict" does not allow writing to /tmp which we need for unpacking the webadmin interface. "full" is less strict.
         };
         "virt-aliases-generator" = {
           description = "Virtual Aliases Generator: Generate a sieve script from the virtual alias file";

nixos/modules/mailman.nix

@@ -32,7 +32,6 @@ in {
         config = {
           transport_maps = ["hash:/var/lib/mailman/data/postfix_lmtp"];
           local_recipient_maps = ["hash:/var/lib/mailman/data/postfix_lmtp"];
-          proxy_interfaces = "130.83.2.184";
           smtputf8_enable = "no"; # HRZ does not know SMTPUTF8
         };
         relayHost = "mathebau.de"; # Relay to mail vm which relays to HRZ (see https://www.hrz.tu-darmstadt.de/services/it_services/email_infrastruktur/index.de.jsp)
@@ -44,7 +43,11 @@ in {
         webHosts = [cfg.hostName];
         serve.enable = true; #
         # Don't include confirmation tokens in reply addresses, because we would need to send them to HRZ otherwise.
-        settings.mta.verp_confirmations = "no";
+        settings.mta = {
+          verp_confirmations = "no";
+          max_recipients = "1"; # We can only send to one recipient at a time due to how forwarding currently works. See also the mail module.
+          max_sessions_per_connection = "1";
+        };
       };
     };