build(deps): Bump golang.org/x/crypto from 0.52.0 to 0.53.0

Bumps [golang.org/x/crypto](https://github.com/golang/crypto) from 0.52.0 to 0.53.0.
- [Commits](https://github.com/golang/crypto/compare/v0.52.0...v0.53.0)

---
updated-dependencies:
- dependency-name: golang.org/x/crypto
  dependency-version: 0.53.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/codeql-analysis.yml

@@ -38,16 +38,16 @@ jobs:
 
     steps:
     - name: Harden Runner
-      uses: step-security/harden-runner@6c3c2f2c1c457b00c10c4848d6f5491db3b629df # v2.18.0
+      uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
       with:
         egress-policy: audit
 
     - name: Checkout repository
-      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@c10b8064de6f491fea524254123dbe5e09572f13 # v4.35.1
+      uses: github/codeql-action/init@8aad20d150bbac5944a9f9d289da16a4b0d87c1e # v4.36.2
       with:
         languages: ${{ matrix.language }}
         # If you wish to specify custom queries, you can do so here or in a config file.
@@ -58,7 +58,7 @@ jobs:
     # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
     # If this step fails, then you should remove it and run the build manually (see below)
     - name: Autobuild
-      uses: github/codeql-action/autobuild@c10b8064de6f491fea524254123dbe5e09572f13 # v4.35.1
+      uses: github/codeql-action/autobuild@8aad20d150bbac5944a9f9d289da16a4b0d87c1e # v4.36.2
 
     # ℹ️ Command-line programs to run using the OS shell.
     # 📚 https://git.io/JvXDl
@@ -72,4 +72,4 @@ jobs:
     #   make release
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@c10b8064de6f491fea524254123dbe5e09572f13 # v4.35.1
+      uses: github/codeql-action/analyze@8aad20d150bbac5944a9f9d289da16a4b0d87c1e # v4.36.2

.github/workflows/dependency-review.yml

@@ -17,11 +17,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@6c3c2f2c1c457b00c10c4848d6f5491db3b629df # v2.18.0
+        uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
         with:
           egress-policy: audit
 
       - name: 'Checkout Repository'
-        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
       - name: 'Dependency Review'
-        uses: actions/dependency-review-action@2031cfc080254a8a887f58cffee85186f0e49e48 # v4.9.0
+        uses: actions/dependency-review-action@a1d282b36b6f3519aa1f3fc636f609c47dddb294 # v5.0.0

.github/workflows/go.yml

@@ -10,11 +10,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Harden Runner
-      uses: step-security/harden-runner@6c3c2f2c1c457b00c10c4848d6f5491db3b629df # v2.18.0
+      uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
       with:
         egress-policy: audit
 
-    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+    - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
     - uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
       with:
         go-version: 'stable'

.github/workflows/release.yaml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
     - name: Harden Runner
-      uses: step-security/harden-runner@6c3c2f2c1c457b00c10c4848d6f5491db3b629df # v2.18.0
+      uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
       with:
         egress-policy: audit
 
@@ -41,7 +41,7 @@ jobs:
           echo "REF=${GITHUB_REF}" >> $GITHUB_ENV
         fi
 
-    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+    - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
       with:
         ref: ${{ env.REF }}
 

.github/workflows/scorecards.yml

@@ -36,12 +36,12 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@6c3c2f2c1c457b00c10c4848d6f5491db3b629df # v2.18.0
+        uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
         with:
           egress-policy: audit
 
       - name: "Checkout code"
-        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           persist-credentials: false
 
@@ -76,6 +76,6 @@ jobs:
 
       # Upload the results to GitHub's code scanning dashboard.
       - name: "Upload to code-scanning"
-        uses: github/codeql-action/upload-sarif@c10b8064de6f491fea524254123dbe5e09572f13 # v4.35.1
+        uses: github/codeql-action/upload-sarif@8aad20d150bbac5944a9f9d289da16a4b0d87c1e # v4.36.2
         with:
           sarif_file: results.sarif

config.go

@@ -31,6 +31,7 @@ var (
 	listenStr        = flagset.String("listen", "127.0.0.1:25 [::1]:25", "Address and port to listen for incoming SMTP")
 	localCert        = flagset.String("local_cert", "", "SSL certificate for STARTTLS/TLS")
 	localKey         = flagset.String("local_key", "", "SSL private key for STARTTLS/TLS")
+	tlsProfile       = flagset.String("tls_profile", "default", "TLS profile: modern | intermediate | default | legacy")
 	localForceTLS    = flagset.Bool("local_forcetls", false, "Force STARTTLS (needs local_cert and local_key)")
 	readTimeoutStr   = flagset.String("read_timeout", "60s", "Socket timeout for read operations")
 	writeTimeoutStr  = flagset.String("write_timeout", "60s", "Socket timeout for write operations")

go.mod

@@ -1,14 +1,14 @@
 module github.com/decke/smtprelay
 
 require (
-	github.com/DeRuina/timberjack v1.4.1
-	github.com/chrj/smtpd v0.4.0
-	github.com/fsnotify/fsnotify v1.9.0
+	github.com/DeRuina/timberjack v1.4.5
+	github.com/chrj/smtpd v1.0.0
+	github.com/fsnotify/fsnotify v1.10.1
 	github.com/google/uuid v1.6.0
 	github.com/peterbourgon/ff/v3 v3.4.0
-	github.com/rs/zerolog v1.35.0
+	github.com/rs/zerolog v1.35.1
 	github.com/stretchr/testify v1.11.1
-	golang.org/x/crypto v0.50.0
+	golang.org/x/crypto v0.53.0
 )
 
 require (
@@ -17,7 +17,7 @@ require (
 	github.com/mattn/go-colorable v0.1.14 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	golang.org/x/sys v0.43.0 // indirect
+	golang.org/x/sys v0.46.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
 

go.sum

@@ -1,13 +1,13 @@
-github.com/DeRuina/timberjack v1.4.1 h1:JftM5HN/ITKehAXjtdbGqN5XZIS1biHm7VSjU0Qbtqg=
-github.com/DeRuina/timberjack v1.4.1/go.mod h1:RLoeQrwrCGIEF8gO5nV5b/gMD0QIy7bzQhBUgpp1EqE=
-github.com/chrj/smtpd v0.4.0 h1:DPJY9XxJngESsV1O/GKeydN6c+iuV1dglW/dw0VlxFY=
-github.com/chrj/smtpd v0.4.0/go.mod h1:zEP61gNDlWp/jdUqBcq/ykIbgOERyRvwfMsRLl3h9gM=
+github.com/DeRuina/timberjack v1.4.5 h1:F/kms5MPNAXUeWdOILt5ALC6iDHWNRPevaeIVH7tqYU=
+github.com/DeRuina/timberjack v1.4.5/go.mod h1:RLoeQrwrCGIEF8gO5nV5b/gMD0QIy7bzQhBUgpp1EqE=
+github.com/chrj/smtpd v1.0.0 h1:jChSfLzAhrSxTky0EZ6oW+UKiqdnepdknWYRkPeA+ZE=
+github.com/chrj/smtpd v1.0.0/go.mod h1:zEP61gNDlWp/jdUqBcq/ykIbgOERyRvwfMsRLl3h9gM=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fortytw2/leaktest v1.3.0 h1:u8491cBMTQ8ft8aeV+adlcytMZylmA5nnwwkRZjI8vw=
 github.com/fortytw2/leaktest v1.3.0/go.mod h1:jDsjWgpAGjm2CA7WthBh/CdZYEPF31XHquHwclZch5g=
-github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
-github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
+github.com/fsnotify/fsnotify v1.10.1 h1:b0/UzAf9yR5rhf3RPm9gf3ehBPpf0oZKIjtpKrx59Ho=
+github.com/fsnotify/fsnotify v1.10.1/go.mod h1:TLheqan6HD6GBK6PrDWyDPBaEV8LspOxvPSjC+bVfgo=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/klauspost/compress v1.18.4 h1:RPhnKRAQ4Fh8zU2FY/6ZFDwTVTxgJ/EMydqSTzE9a2c=
@@ -20,15 +20,15 @@ github.com/peterbourgon/ff/v3 v3.4.0 h1:QBvM/rizZM1cB0p0lGMdmR7HxZeI/ZrBWB4DqLkM
 github.com/peterbourgon/ff/v3 v3.4.0/go.mod h1:zjJVUhx+twciwfDl0zBcFzl4dW8axCRyXE/eKY9RztQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/rs/zerolog v1.35.0 h1:VD0ykx7HMiMJytqINBsKcbLS+BJ4WYjz+05us+LRTdI=
-github.com/rs/zerolog v1.35.0/go.mod h1:EjML9kdfa/RMA7h/6z6pYmq1ykOuA8/mjWaEvGI+jcw=
+github.com/rs/zerolog v1.35.1 h1:m7xQeoiLIiV0BCEY4Hs+j2NG4Gp2o2KPKmhnnLiazKI=
+github.com/rs/zerolog v1.35.1/go.mod h1:EjML9kdfa/RMA7h/6z6pYmq1ykOuA8/mjWaEvGI+jcw=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
-golang.org/x/crypto v0.50.0 h1:zO47/JPrL6vsNkINmLoo/PH1gcxpls50DNogFvB5ZGI=
-golang.org/x/crypto v0.50.0/go.mod h1:3muZ7vA7PBCE6xgPX7nkzzjiUq87kRItoJQM1Yo8S+Q=
+golang.org/x/crypto v0.53.0 h1:QZ4Muo8THX6CizN2vPPd5fBGHyogrdK9fG4wLPFUsto=
+golang.org/x/crypto v0.53.0/go.mod h1:DNLU434OwVakk9PzuwV8w62mAJpRJL3vsgcfp4Qnsio=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.43.0 h1:Rlag2XtaFTxp19wS8MXlJwTvoh8ArU6ezoyFsMyCTNI=
-golang.org/x/sys v0.43.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/sys v0.46.0 h1:noSf2Fq6F8DBgS+LysIkx7rIExoNHJsxOAtPp4rthXw=
+golang.org/x/sys v0.46.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

main.go

@@ -281,6 +281,7 @@ func generateUUID() string {
 }
 
 func getTLSConfig() *tls.Config {
+	// Certificate loading / validation
 	if *localCert == "" || *localKey == "" {
 		log.Fatal().
 			Str("cert_file", *localCert).
@@ -295,9 +296,60 @@ func getTLSConfig() *tls.Config {
 			Msg("cannot load X509 keypair")
 	}
 
-	return &tls.Config{
+	// TLS profile configuration
+	// tls.Config.CipherSuites only affects TLS 1.0–1.2.
+
+	// Base config: Go defaults unless overridden.
+	conf := &tls.Config{
 		Certificates: []tls.Certificate{cert},
 	}
+
+	profile := strings.ToLower(strings.TrimSpace(*tlsProfile))
+	if profile == "" {
+		profile = "default"
+	}
+
+	switch profile {
+	case "default":
+		// Go defaults (leave MinVersion/MaxVersion/CipherSuites unset).
+
+	case "modern":
+		// TLS 1.3+.
+		conf.MinVersion = tls.VersionTLS13
+
+	case "intermediate":
+		// TLS 1.2+ with AEAD + ECDHE cipher suites only.
+		// Mozilla "intermediate" — AEAD + ECDHE only.
+		conf.MinVersion = tls.VersionTLS12
+		conf.CipherSuites = []uint16{
+			tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+			tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+			tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+			tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+			tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
+			tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
+		}
+
+	case "legacy":
+		// Last resort: TLS 1.0+ and everything Go exposes for TLS 1.0–1.2.
+		conf.MinVersion = tls.VersionTLS10
+
+		allSuites := []uint16{}
+		for _, cs := range tls.CipherSuites() {
+			allSuites = append(allSuites, cs.ID)
+		}
+		for _, cs := range tls.InsecureCipherSuites() {
+			allSuites = append(allSuites, cs.ID)
+		}
+		conf.CipherSuites = allSuites
+
+	default:
+		log.Warn().
+			Str("tls_profile", profile).
+			Msg("unknown tls_profile; using default")
+	}
+
+	return conf
 }
 
 func watchAliasFile() {

smtprelay.ini

@@ -35,6 +35,33 @@
 ;local_cert = smtpd.pem
 ;local_key  = smtpd.key
 
+; TLS PROFILE (STARTTLS / TLS listeners)
+; Controls the minimum TLS version and allowed cipher suites for inbound
+; connections when using listen protocols `starttls://` or `tls://`.
+; Profiles follow the Mozilla SSL Configuration Generator guidelines.
+;
+;   default
+;     Go standard library defaults. Tracks improvements as Go updates
+;     its TLS defaults. Recommended for most deployments.
+;
+;   modern
+;     TLS 1.3+ only. Simplest and most secure, but rejects any client
+;     that cannot negotiate TLS 1.3.
+;     Matches Mozilla "modern" configuration.
+;
+;   intermediate
+;     TLS 1.2+. For TLS 1.2 connections only AEAD ciphers (AES-GCM,
+;     ChaCha20-Poly1305) with ECDHE key exchange are allowed,
+;     providing forward secrecy. TLS 1.3 ciphers are always available.
+;     Matches Mozilla "intermediate" configuration.
+;
+;   legacy
+;     TLS 1.0+ with all cipher suites the Go standard library supports,
+;     including insecure ones (RC4, 3DES). Use only when you must
+;     support very old clients that cannot negotiate TLS 1.2.
+;
+;tls_profile=default
+
 ; Enforce encrypted connection on STARTTLS ports before
 ; accepting mails from client.
 ;local_forcetls = false