add support for DHGEX

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

docs/full-configuration.md

@@ -129,7 +129,8 @@ The configuration file contains the following sections:
   - `host_keys`, list of strings. It contains the daemon's private host keys. Each host key can be defined as a path relative to the configuration directory or an absolute one. If empty, the daemon will search or try to generate `id_rsa`, `id_ecdsa` and `id_ed25519` keys inside the configuration directory. If you configure absolute paths to files named `id_rsa`, `id_ecdsa` and/or `id_ed25519` then SFTPGo will try to generate these keys using the default settings.
   - `host_certificates`, list of strings. Public host certificates. Each certificate can be defined as a path relative to the configuration directory or an absolute one. Certificate's public key must match a private host key otherwise it will be silently ignored. Default: empty.
   - `host_key_algorithms`, list of strings. Public key algorithms that the server will accept for host key authentication. The supported values are: `rsa-sha2-512-cert-v01@openssh.com`, `rsa-sha2-256-cert-v01@openssh.com`, `ssh-rsa-cert-v01@openssh.com`, `ssh-dss-cert-v01@openssh.com`, `ecdsa-sha2-nistp256-cert-v01@openssh.com`, `ecdsa-sha2-nistp384-cert-v01@openssh.com`, `ecdsa-sha2-nistp521-cert-v01@openssh.com`, `ssh-ed25519-cert-v01@openssh.com`, `ecdsa-sha2-nistp256`, `ecdsa-sha2-nistp384`, `ecdsa-sha2-nistp521`, `rsa-sha2-512`, `rsa-sha2-256`, `ssh-rsa`, `ssh-dss`, `ssh-ed25519`. Default values: `rsa-sha2-512-cert-v01@openssh.com`, `rsa-sha2-256-cert-v01@openssh.com`, `ecdsa-sha2-nistp256-cert-v01@openssh.com`, `ecdsa-sha2-nistp384-cert-v01@openssh.com`, `ecdsa-sha2-nistp521-cert-v01@openssh.com`, `ssh-ed25519-cert-v01@openssh.com`, `ecdsa-sha2-nistp256`, `ecdsa-sha2-nistp384`, `ecdsa-sha2-nistp521`, `rsa-sha2-512`, `rsa-sha2-256`, `ssh-ed25519`.
-  - `kex_algorithms`, list of strings. Available KEX (Key Exchange) algorithms in preference order. Leave empty to use default values. The supported values are: `curve25519-sha256`, `curve25519-sha256@libssh.org`, `ecdh-sha2-nistp256`, `ecdh-sha2-nistp384`, `ecdh-sha2-nistp521`, `diffie-hellman-group14-sha256`, `diffie-hellman-group16-sha512`, `diffie-hellman-group18-sha512`, `diffie-hellman-group14-sha1`, `diffie-hellman-group1-sha1`. Default values: `curve25519-sha256`, `curve25519-sha256@libssh.org`, `ecdh-sha2-nistp256`, `ecdh-sha2-nistp384`, `ecdh-sha2-nistp521`, `diffie-hellman-group14-sha256`. SHA512 based KEXs are disabled by default because they are slow.
+  - `moduli`, list of strings. Diffie-Hellman moduli files. Each moduli file can be defined as a path relative to the configuration directory or an absolute one. If set, `diffie-hellman-group-exchange-sha256` and `diffie-hellman-group-exchange-sha1` KEX algorithms will be available, `diffie-hellman-group-exchange-sha256` will be enabled by default if you don't explicitly set KEXs. Default: empty.
+  - `kex_algorithms`, list of strings. Available KEX (Key Exchange) algorithms in preference order. Leave empty to use default values. The supported values are: `curve25519-sha256`, `curve25519-sha256@libssh.org`, `ecdh-sha2-nistp256`, `ecdh-sha2-nistp384`, `ecdh-sha2-nistp521`, `diffie-hellman-group14-sha256`, `diffie-hellman-group16-sha512`, `diffie-hellman-group18-sha512`, `diffie-hellman-group14-sha1`, `diffie-hellman-group1-sha1`. Default values: `curve25519-sha256`, `curve25519-sha256@libssh.org`, `ecdh-sha2-nistp256`, `ecdh-sha2-nistp384`, `ecdh-sha2-nistp521`, `diffie-hellman-group14-sha256`. SHA512 based KEXs are disabled by default because they are slow. If you set one or more moduli files,  `diffie-hellman-group-exchange-sha256` and `diffie-hellman-group-exchange-sha1` will be available.
   - `ciphers`, list of strings. Allowed ciphers in preference order. Leave empty to use default values. The supported values are: `aes128-gcm@openssh.com`, `aes256-gcm@openssh.com`, `chacha20-poly1305@openssh.com`, `aes128-ctr`, `aes192-ctr`, `aes256-ctr`, `aes128-cbc`, `aes192-cbc`, `aes256-cbc`, `3des-cbc`, `arcfour256`, `arcfour128`, `arcfour`. Default values: `aes128-gcm@openssh.com`, `aes256-gcm@openssh.com`, `chacha20-poly1305@openssh.com`, `aes128-ctr`, `aes192-ctr`, `aes256-ctr`. Please note that the ciphers disabled by default are insecure, you should expect that an active attacker can recover plaintext if you enable them.
   - `macs`, list of strings. Available MAC (message authentication code) algorithms in preference order. Leave empty to use default values. The supported values are: `hmac-sha2-256-etm@openssh.com`, `hmac-sha2-256`, `hmac-sha2-512-etm@openssh.com`, `hmac-sha2-512`, `hmac-sha1`, `hmac-sha1-96`. Default values: `hmac-sha2-256-etm@openssh.com`, `hmac-sha2-256`.
   - `trusted_user_ca_keys`, list of public keys paths of certificate authorities that are trusted to sign user certificates for authentication. The paths can be absolute or relative to the configuration directory.

go.mod

@@ -9,14 +9,14 @@ require (
 	github.com/GehirnInc/crypt v0.0.0-20200316065508-bb7000b8a962
 	github.com/alexedwards/argon2id v0.0.0-20211130144151-3585854a6387
 	github.com/aws/aws-sdk-go-v2 v1.17.1
-	github.com/aws/aws-sdk-go-v2/config v1.18.0
-	github.com/aws/aws-sdk-go-v2/credentials v1.13.0
+	github.com/aws/aws-sdk-go-v2/config v1.18.1
+	github.com/aws/aws-sdk-go-v2/credentials v1.13.1
 	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.12.19
-	github.com/aws/aws-sdk-go-v2/feature/s3/manager v1.11.39
-	github.com/aws/aws-sdk-go-v2/service/marketplacemetering v1.13.22
-	github.com/aws/aws-sdk-go-v2/service/s3 v1.29.2
-	github.com/aws/aws-sdk-go-v2/service/secretsmanager v1.16.5
-	github.com/aws/aws-sdk-go-v2/service/sts v1.17.2
+	github.com/aws/aws-sdk-go-v2/feature/s3/manager v1.11.40
+	github.com/aws/aws-sdk-go-v2/service/marketplacemetering v1.13.23
+	github.com/aws/aws-sdk-go-v2/service/s3 v1.29.3
+	github.com/aws/aws-sdk-go-v2/service/secretsmanager v1.16.6
+	github.com/aws/aws-sdk-go-v2/service/sts v1.17.3
 	github.com/cockroachdb/cockroach-go/v2 v2.2.18
 	github.com/coreos/go-oidc/v3 v3.4.0
 	github.com/drakkan/webdav v0.0.0-20221101181759-17ed21f9337b
@@ -66,7 +66,7 @@ require (
 	go.etcd.io/bbolt v1.3.6
 	go.uber.org/automaxprocs v1.5.1
 	gocloud.dev v0.27.0
-	golang.org/x/crypto v0.2.0
+	golang.org/x/crypto v0.3.0
 	golang.org/x/net v0.2.0
 	golang.org/x/oauth2 v0.2.0
 	golang.org/x/sys v0.2.0
@@ -138,7 +138,7 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/oklog/run v1.1.0 // indirect
 	github.com/pelletier/go-toml v1.9.5 // indirect
-	github.com/pelletier/go-toml/v2 v2.0.5 // indirect
+	github.com/pelletier/go-toml/v2 v2.0.6 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/power-devops/perfstat v0.0.0-20220216144756-c35f1ee13d7c // indirect
 	github.com/prometheus/client_model v0.3.0 // indirect
@@ -158,7 +158,7 @@ require (
 	golang.org/x/tools v0.3.0 // indirect
 	golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
-	google.golang.org/genproto v0.0.0-20221114212237-e4508ebdbee1 // indirect
+	google.golang.org/genproto v0.0.0-20221116193143-41c2ba794472 // indirect
 	google.golang.org/grpc v1.50.1 // indirect
 	google.golang.org/protobuf v1.28.1 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
@@ -169,5 +169,5 @@ require (
 
 replace (
 	github.com/jlaffaye/ftp => github.com/drakkan/ftp v0.0.0-20201114075148-9b9adce499a9
-	golang.org/x/crypto => github.com/drakkan/crypto v0.0.0-20221020054403-a265c1cba3cb
+	golang.org/x/crypto => github.com/drakkan/crypto v0.0.0-20221117111000-a0321143587c
 )

go.sum

@@ -233,17 +233,17 @@ github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.4.3/go.mod h1:gNsR5CaXK
 github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.4.9 h1:RKci2D7tMwpvGpDNZnGQw9wk6v7o/xSwFcUAuNPoB8k=
 github.com/aws/aws-sdk-go-v2/aws/protocol/eventstream v1.4.9/go.mod h1:vCmV1q1VK8eoQJ5+aYE7PkK1K6v41qJ5pJdK3ggCDvg=
 github.com/aws/aws-sdk-go-v2/config v1.15.15/go.mod h1:A1Lzyy/o21I5/s2FbyX5AevQfSVXpvvIDCoVFD0BC4E=
-github.com/aws/aws-sdk-go-v2/config v1.18.0 h1:ULASZmfhKR/QE9UeZ7mzYjUzsnIydy/K1YMT6uH1KC0=
-github.com/aws/aws-sdk-go-v2/config v1.18.0/go.mod h1:H13DRX9Nv5tAcQvPABrE3dm5XnLp1RC7fVSM3OWiLvA=
+github.com/aws/aws-sdk-go-v2/config v1.18.1 h1:wMzU9tBq/tEdTUcmB9WsYe5stdP0/EAf84vfeqS5S6A=
+github.com/aws/aws-sdk-go-v2/config v1.18.1/go.mod h1:jQIgBmQJa5oPzTUtWMjFryPDCBlVqIgoFmdfFKLx4WE=
 github.com/aws/aws-sdk-go-v2/credentials v1.12.10/go.mod h1:g5eIM5XRs/OzIIK81QMBl+dAuDyoLN0VYaLP+tBqEOk=
-github.com/aws/aws-sdk-go-v2/credentials v1.13.0 h1:W5f73j1qurASap+jdScUo4aGzSXxaC7wq1i7CiwhvU8=
-github.com/aws/aws-sdk-go-v2/credentials v1.13.0/go.mod h1:prZpUfBu1KZLBLVX482Sq4DpDXGugAre08TPEc21GUg=
+github.com/aws/aws-sdk-go-v2/credentials v1.13.1 h1:HusGjp9C8zwu1SSEh3s501Llqr2xhn+FYKV5XMnOt6M=
+github.com/aws/aws-sdk-go-v2/credentials v1.13.1/go.mod h1:C8xoJdzfQq/kl6gGIuJeHpcAaZnraJfTV9FoBgW1QYg=
 github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.12.9/go.mod h1:KDCCm4ONIdHtUloDcFvK2+vshZvx4Zmj7UMDfusuz5s=
 github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.12.19 h1:E3PXZSI3F2bzyj6XxUXdTIfvp425HHhwKsFvmzBwHgs=
 github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.12.19/go.mod h1:VihW95zQpeKQWVPGkwT+2+WJNQV8UXFfMTWdU6VErL8=
 github.com/aws/aws-sdk-go-v2/feature/s3/manager v1.11.21/go.mod h1:iIYPrQ2rYfZiB/iADYlhj9HHZ9TTi6PqKQPAqygohbE=
-github.com/aws/aws-sdk-go-v2/feature/s3/manager v1.11.39 h1:Fz/t08vTFdz63ZnlrQBLOMgBCNqdKmMQWE/XjKm1jt4=
-github.com/aws/aws-sdk-go-v2/feature/s3/manager v1.11.39/go.mod h1:763L1Xloj/mjT0do5k9d0qh0vEAVuomDPn1iOG2AdB4=
+github.com/aws/aws-sdk-go-v2/feature/s3/manager v1.11.40 h1:Q8Pshd76l1y24DSWJrQPyYY6xVNmpcsZHEfE9xZ4rpU=
+github.com/aws/aws-sdk-go-v2/feature/s3/manager v1.11.40/go.mod h1:rxGAF7fGMCse4bUVO+55P1mWCMCnUZPmh3LAnl0PZms=
 github.com/aws/aws-sdk-go-v2/internal/configsources v1.1.15/go.mod h1:pWrr2OoHlT7M/Pd2y4HV3gJyPb3qj5qMmnPkKSNPYK4=
 github.com/aws/aws-sdk-go-v2/internal/configsources v1.1.25 h1:nBO/RFxeq/IS5G9Of+ZrgucRciie2qpLy++3UGZ+q2E=
 github.com/aws/aws-sdk-go-v2/internal/configsources v1.1.25/go.mod h1:Zb29PYkf42vVYQY6pvSyJCJcFHlPIiY+YKdPtwnvMkY=
@@ -269,14 +269,14 @@ github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.13.9/go.mod h1:Rc5+wn2
 github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.13.19 h1:piDBAaWkaxkkVV3xJJbTehXCZRXYs49kvpi/LG6LR2o=
 github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.13.19/go.mod h1:BmQWRVkLTmyNzYPFAZgon53qKLWBNSvonugD1MrSWUs=
 github.com/aws/aws-sdk-go-v2/service/kms v1.18.1/go.mod h1:4PZMUkc9rXHWGVB5J9vKaZy3D7Nai79ORworQ3ASMiM=
-github.com/aws/aws-sdk-go-v2/service/marketplacemetering v1.13.22 h1:abXVcIh8pjiuWdPBk8vZYwxO5yZCmRHR8grHf6ZqCdY=
-github.com/aws/aws-sdk-go-v2/service/marketplacemetering v1.13.22/go.mod h1:mRGY+k3s1yt7yQA3AfzJhnr68OCs1xDfQfIABFUk+ek=
+github.com/aws/aws-sdk-go-v2/service/marketplacemetering v1.13.23 h1:NZKyAfM6J2OPehuSZI8woNGTxYi5jMkTDWGEFwR6/FA=
+github.com/aws/aws-sdk-go-v2/service/marketplacemetering v1.13.23/go.mod h1:mRGY+k3s1yt7yQA3AfzJhnr68OCs1xDfQfIABFUk+ek=
 github.com/aws/aws-sdk-go-v2/service/s3 v1.27.2/go.mod h1:u+566cosFI+d+motIz3USXEh6sN8Nq4GrNXSg2RXVMo=
-github.com/aws/aws-sdk-go-v2/service/s3 v1.29.2 h1:l29X5biLks99HzZzQgC78plJpwiMv/pGNhmaTM2z62A=
-github.com/aws/aws-sdk-go-v2/service/s3 v1.29.2/go.mod h1:/NHbqPRiwxSPVOB2Xr+StDEH+GWV/64WwnUjv4KYzV0=
+github.com/aws/aws-sdk-go-v2/service/s3 v1.29.3 h1:F6wgg8aHGNyhaAy2ONnWBThiPdLa386qNA0j33FIuSM=
+github.com/aws/aws-sdk-go-v2/service/s3 v1.29.3/go.mod h1:/NHbqPRiwxSPVOB2Xr+StDEH+GWV/64WwnUjv4KYzV0=
 github.com/aws/aws-sdk-go-v2/service/secretsmanager v1.15.14/go.mod h1:xakbH8KMsQQKqzX87uyyzTHshc/0/Df8bsTneTS5pFU=
-github.com/aws/aws-sdk-go-v2/service/secretsmanager v1.16.5 h1:De+sGzRmk6+/lzKqZXa6RdC1ZVGLPHI1nvjOxw4ooj0=
-github.com/aws/aws-sdk-go-v2/service/secretsmanager v1.16.5/go.mod h1:k6CPuxyzO247nYEM1baEwHH1kRtosRCvgahAepaaShw=
+github.com/aws/aws-sdk-go-v2/service/secretsmanager v1.16.6 h1:TMIXEKw1ak/OPXGBTwBORU4aR921XFbj7pFsDPn45go=
+github.com/aws/aws-sdk-go-v2/service/secretsmanager v1.16.6/go.mod h1:k6CPuxyzO247nYEM1baEwHH1kRtosRCvgahAepaaShw=
 github.com/aws/aws-sdk-go-v2/service/sns v1.17.10/go.mod h1:uITsRNVMeCB3MkWpXxXw0eDz8pW4TYLzj+eyQtbhSxM=
 github.com/aws/aws-sdk-go-v2/service/sqs v1.19.1/go.mod h1:A94o564Gj+Yn+7QO1eLFeI7UVv3riy/YBFOfICVqFvU=
 github.com/aws/aws-sdk-go-v2/service/ssm v1.27.6/go.mod h1:fiFzQgj4xNOg4/wqmAiPvzgDMXPD+cUEplX/CYn+0j0=
@@ -286,8 +286,8 @@ github.com/aws/aws-sdk-go-v2/service/sso v1.11.25/go.mod h1:IARHuzTXmj1C0KS35vbo
 github.com/aws/aws-sdk-go-v2/service/ssooidc v1.13.8 h1:jcw6kKZrtNfBPJkaHrscDOZoe5gvi9wjudnxvozYFJo=
 github.com/aws/aws-sdk-go-v2/service/ssooidc v1.13.8/go.mod h1:er2JHN+kBY6FcMfcBBKNGCT3CarImmdFzishsqBmSRI=
 github.com/aws/aws-sdk-go-v2/service/sts v1.16.10/go.mod h1:cftkHYN6tCDNfkSasAmclSfl4l7cySoay8vz7p/ce0E=
-github.com/aws/aws-sdk-go-v2/service/sts v1.17.2 h1:tpwEMRdMf2UsplengAOnmSIRdvAxf75oUFR+blBr92I=
-github.com/aws/aws-sdk-go-v2/service/sts v1.17.2/go.mod h1:bXcN3koeVYiJcdDU89n3kCYILob7Y34AeLopUbZgLT4=
+github.com/aws/aws-sdk-go-v2/service/sts v1.17.3 h1:WMAsVk4yQTHOZ2m7dFnF5Azr/aDecBbpWRwc+M6iFIM=
+github.com/aws/aws-sdk-go-v2/service/sts v1.17.3/go.mod h1:bXcN3koeVYiJcdDU89n3kCYILob7Y34AeLopUbZgLT4=
 github.com/aws/smithy-go v1.12.0/go.mod h1:Tg+OJXh4MB2R/uN61Ko2f6hTZwB/ZYGOtib8J3gBHzA=
 github.com/aws/smithy-go v1.13.4 h1:/RN2z1txIJWeXeOkzX+Hk/4Uuvv7dWtCjbmVJcrskyk=
 github.com/aws/smithy-go v1.13.4/go.mod h1:Tg+OJXh4MB2R/uN61Ko2f6hTZwB/ZYGOtib8J3gBHzA=
@@ -536,8 +536,8 @@ github.com/docker/go-units v0.4.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDD
 github.com/docker/libtrust v0.0.0-20150114040149-fa567046d9b1/go.mod h1:cyGadeNEkKy96OOhEzfZl+yxihPEzKnqJwvfuSUqbZE=
 github.com/docker/spdystream v0.0.0-20160310174837-449fdfce4d96/go.mod h1:Qh8CwZgvJUkLughtfhJv5dyTYa91l1fOUCrgjqmcifM=
 github.com/docopt/docopt-go v0.0.0-20180111231733-ee0de3bc6815/go.mod h1:WwZ+bS3ebgob9U8Nd0kOddGdZWjyMGR8Wziv+TBNwSE=
-github.com/drakkan/crypto v0.0.0-20221020054403-a265c1cba3cb h1:ex3x8ir969oV6bQ8fBYlaw1DXKGZCOM560bdeqeDJ/Y=
-github.com/drakkan/crypto v0.0.0-20221020054403-a265c1cba3cb/go.mod h1:IBSs4ri4rdTqz2QKcpTKpwKMdM+WJ7atZeL9lCu2swQ=
+github.com/drakkan/crypto v0.0.0-20221117111000-a0321143587c h1:3lJRXQcGw8fnheQ9ORGYE17JLuYzu6FkDuK8MZwqeRQ=
+github.com/drakkan/crypto v0.0.0-20221117111000-a0321143587c/go.mod h1:z/3TjBrBT/Dch7NfsgFg7f07WiGYZVYQgnxGHacCvRc=
 github.com/drakkan/ftp v0.0.0-20201114075148-9b9adce499a9 h1:LPH1dEblAOO/LoG7yHPMtBLXhQmjaga91/DDjWk9jWA=
 github.com/drakkan/ftp v0.0.0-20201114075148-9b9adce499a9/go.mod h1:2lmrmq866uF2tnje75wQHzmPXhmSWUt7Gyx2vgK1RCU=
 github.com/drakkan/webdav v0.0.0-20221101181759-17ed21f9337b h1:B9z7XyDoVxLO4yEvnXgdvZ+0Uw9NA1qdD4KTSGmKcoQ=
@@ -1059,7 +1059,6 @@ github.com/klauspost/compress v1.15.1/go.mod h1:/3/Vjq9QcHkK5uEr5lBEmyoZ1iFhe47e
 github.com/klauspost/compress v1.15.12 h1:YClS/PImqYbn+UILDnqxQCZ3RehC9N318SU3kElDUEM=
 github.com/klauspost/compress v1.15.12/go.mod h1:QPwzmACJjUTFsnSHH934V6woptycfrDDJnH7hvFVbGM=
 github.com/klauspost/cpuid/v2 v2.0.4/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
-github.com/klauspost/cpuid/v2 v2.1.2/go.mod h1:RVVoqg1df56z8g3pUjL/3lE5UfnlrJX8tyFgg4nqhuY=
 github.com/klauspost/cpuid/v2 v2.2.1 h1:U33DW0aiEj633gHYw3LoDNfkDiYnE5Q8M/TKJn2f2jI=
 github.com/klauspost/cpuid/v2 v2.2.1/go.mod h1:RVVoqg1df56z8g3pUjL/3lE5UfnlrJX8tyFgg4nqhuY=
 github.com/kolo/xmlrpc v0.0.0-20201022064351-38db28db192b/go.mod h1:pcaDhQK0/NJZEvtCO0qQPPropqV0sJOJ6YW7X+9kRwM=
@@ -1313,8 +1312,8 @@ github.com/pelletier/go-toml v1.8.1/go.mod h1:T2/BmBdy8dvIRq1a/8aqjN41wvWlN4lrap
 github.com/pelletier/go-toml v1.9.3/go.mod h1:u1nR/EPcESfeI/szUZKdtJ0xRNbUoANCkoOuaOx1Y+c=
 github.com/pelletier/go-toml v1.9.5 h1:4yBQzkHv+7BHq2PQUZF3Mx0IYxG7LsP222s7Agd3ve8=
 github.com/pelletier/go-toml v1.9.5/go.mod h1:u1nR/EPcESfeI/szUZKdtJ0xRNbUoANCkoOuaOx1Y+c=
-github.com/pelletier/go-toml/v2 v2.0.5 h1:ipoSadvV8oGUjnUbMub59IDPPwfxF694nG/jwbMiyQg=
-github.com/pelletier/go-toml/v2 v2.0.5/go.mod h1:OMHamSCAODeSsVrwwvcJOaoN0LIUIaFVNZzmWyNfXas=
+github.com/pelletier/go-toml/v2 v2.0.6 h1:nrzqCb7j9cDFj2coyLNLaZuJTLjWjlaz6nvTvIwycIU=
+github.com/pelletier/go-toml/v2 v2.0.6/go.mod h1:eumQOmlWiOPt5WriQQqoM5y18pDHwha2N+QD+EUNTek=
 github.com/performancecopilot/speed v3.0.0+incompatible/go.mod h1:/CLtqpZ5gBg1M9iaPbIdPPGyKcA8hKdoy6hAWba7Yac=
 github.com/peterbourgon/diskv v2.0.1+incompatible/go.mod h1:uqqh8zWWbv1HBMNONnaR/tNboyR3/BZd58JJSHlUSCU=
 github.com/pierrec/lz4 v1.0.2-0.20190131084431-473cd7ce01a1/go.mod h1:3/3N9NVKO0jef7pBehbT1qWhCMrIgbYNnFAZCqQ5LRc=
@@ -1812,7 +1811,6 @@ golang.org/x/net v0.0.0-20220624214902-1bab6f366d9e/go.mod h1:XRhObCWvk6IyKnWLug
 golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
 golang.org/x/net v0.0.0-20220802222814-0bcc04d9c69b/go.mod h1:YDH+HFinaLZZlnHAfSS6ZXJJ9M9t4Dl22yv3iI2vPwk=
 golang.org/x/net v0.0.0-20220826154423-83b083e8dc8b/go.mod h1:YDH+HFinaLZZlnHAfSS6ZXJJ9M9t4Dl22yv3iI2vPwk=
-golang.org/x/net v0.1.0/go.mod h1:Cx3nUiGt4eDBEyega/BKRp+/AlGL8hYe7U9odMt2Cco=
 golang.org/x/net v0.2.0 h1:sZfSu1wtKLGlWI4ZZayP0ck9Y73K1ynO6gqzTdBVdPU=
 golang.org/x/net v0.2.0/go.mod h1:KqCZLdyyvdV855qA2rE3GC2aiw5xGR5TEjj8smXukLY=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
@@ -2004,15 +2002,14 @@ golang.org/x/sys v0.0.0-20220728004956-3c1f35247d10/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220731174439-a90be440212d/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.2.0 h1:ljd4t30dBnAvMZaQCevtY0xLLD0A+bRZXbgLMLU1F/A=
 golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210220032956-6a3ed077a48d/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
-golang.org/x/term v0.1.0/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.2.0 h1:z85xZCsEl7bi/KwbNADeBYoOP0++7W1ipu+aGnpwzRM=
+golang.org/x/term v0.2.0/go.mod h1:TVmDHMZPmdnySmBfhjOoOdhjzdE1h4u1VwSiw2l1Nuc=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -2295,8 +2292,8 @@ google.golang.org/genproto v0.0.0-20220617124728-180714bec0ad/go.mod h1:KEWEmljW
 google.golang.org/genproto v0.0.0-20220624142145-8cd45d7dbd1f/go.mod h1:KEWEmljWE5zPzLBa/oHl6DaEt9LmfH6WtH1OHIvleBA=
 google.golang.org/genproto v0.0.0-20220628213854-d9e0b6570c03/go.mod h1:KEWEmljWE5zPzLBa/oHl6DaEt9LmfH6WtH1OHIvleBA=
 google.golang.org/genproto v0.0.0-20220802133213-ce4fa296bf78/go.mod h1:iHe1svFLAZg9VWz891+QbRMwUv9O/1Ww+/mngYeThbc=
-google.golang.org/genproto v0.0.0-20221114212237-e4508ebdbee1 h1:jCw9YRd2s40X9Vxi4zKsPRvSPlHWNqadVkpbMsCPzPQ=
-google.golang.org/genproto v0.0.0-20221114212237-e4508ebdbee1/go.mod h1:rZS5c/ZVYMaOGBfO68GWtjOw/eLaZM1X6iVtgjZ+EWg=
+google.golang.org/genproto v0.0.0-20221116193143-41c2ba794472 h1:kIfItBRE5gkUKpH4H5lNGciZbka1JrmRli3ArqrKFkA=
+google.golang.org/genproto v0.0.0-20221116193143-41c2ba794472/go.mod h1:rZS5c/ZVYMaOGBfO68GWtjOw/eLaZM1X6iVtgjZ+EWg=
 google.golang.org/grpc v0.0.0-20160317175043-d3ddb4469d5a/go.mod h1:yo6s7OP7yaDglbqo1J04qKzAhqBH6lvTonzMVmEdcZw=
 google.golang.org/grpc v1.17.0/go.mod h1:6QZJwpn2B+Zp71q/5VxRsJ6NXXVCE5NRUHRo+f3cWCs=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=

internal/config/config.go

@@ -253,6 +253,7 @@ func Init() {
 			HostKeys:                          []string{},
 			HostCertificates:                  []string{},
 			HostKeyAlgorithms:                 []string{},
+			Moduli:                            []string{},
 			KexAlgorithms:                     []string{},
 			Ciphers:                           []string{},
 			MACs:                              []string{},
@@ -1961,6 +1962,7 @@ func setViperDefaults() {
 	viper.SetDefault("sftpd.host_keys", globalConf.SFTPD.HostKeys)
 	viper.SetDefault("sftpd.host_certificates", globalConf.SFTPD.HostCertificates)
 	viper.SetDefault("sftpd.host_key_algorithms", globalConf.SFTPD.HostKeyAlgorithms)
+	viper.SetDefault("sftpd.moduli", globalConf.SFTPD.Moduli)
 	viper.SetDefault("sftpd.kex_algorithms", globalConf.SFTPD.KexAlgorithms)
 	viper.SetDefault("sftpd.ciphers", globalConf.SFTPD.Ciphers)
 	viper.SetDefault("sftpd.macs", globalConf.SFTPD.MACs)

internal/sftpd/internal_test.go

@@ -1926,6 +1926,30 @@ func TestSupportedSecurityOptions(t *testing.T) {
 	assert.Equal(t, supportedKexAlgos, serverConfig.KeyExchanges)
 }
 
+func TestLoadModuli(t *testing.T) {
+	dhGEXSha1 := "diffie-hellman-group-exchange-sha1"
+	dhGEXSha256 := "diffie-hellman-group-exchange-sha256"
+	c := Configuration{}
+	c.Moduli = []string{".", "missing file"}
+	err := c.loadModuli(configDir)
+	assert.Error(t, err)
+	assert.NotContains(t, supportedKexAlgos, dhGEXSha1)
+	assert.NotContains(t, supportedKexAlgos, dhGEXSha256)
+	assert.Len(t, supportedKexAlgos, 10)
+	moduli := []byte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
+	moduliFile := filepath.Join(os.TempDir(), "moduli")
+	err = os.WriteFile(moduliFile, moduli, 0600)
+	assert.NoError(t, err)
+	c.Moduli = []string{moduliFile}
+	err = c.loadModuli(configDir)
+	assert.NoError(t, err)
+	assert.Contains(t, supportedKexAlgos, dhGEXSha1)
+	assert.Contains(t, supportedKexAlgos, dhGEXSha256)
+	assert.Len(t, supportedKexAlgos, 12)
+	err = os.Remove(moduliFile)
+	assert.NoError(t, err)
+}
+
 func TestLoadHostKeys(t *testing.T) {
 	serverConfig := &ssh.ServerConfig{}
 	c := Configuration{}

internal/sftpd/server.go

@@ -141,6 +141,12 @@ type Configuration struct {
 	// HostKeyAlgorithms lists the public key algorithms that the server will accept for host
 	// key authentication.
 	HostKeyAlgorithms []string `json:"host_key_algorithms" mapstructure:"host_key_algorithms"`
+	// Diffie-Hellman moduli files.
+	// Each moduli file can be defined as a path relative to the configuration directory or an absolute one.
+	// If set, "diffie-hellman-group-exchange-sha256" and "diffie-hellman-group-exchange-sha1" KEX algorithms
+	// will be available, `diffie-hellman-group-exchange-sha256` will be enabled by default if you
+	// don't explicitly set KEXs
+	Moduli []string `json:"moduli" mapstructure:"moduli"`
 	// KexAlgorithms specifies the available KEX (Key Exchange) algorithms in
 	// preference order.
 	KexAlgorithms []string `json:"kex_algorithms" mapstructure:"kex_algorithms"`
@@ -294,6 +300,10 @@ func (c *Configuration) Initialize(configDir string) error {
 		return err
 	}
 
+	if err := c.loadModuli(configDir); err != nil {
+		return err
+	}
+
 	sftp.SetSFTPExtensions(sftpExtensions...) //nolint:errcheck // we configure valid SFTP Extensions so we cannot get an error
 
 	if err := c.configureSecurityOptions(serverConfig); err != nil {
@@ -840,6 +850,29 @@ func (c *Configuration) checkHostKeyAutoGeneration(configDir string) error {
 	return nil
 }
 
+func (c *Configuration) loadModuli(configDir string) error {
+	supportedKexAlgos = util.Remove(supportedKexAlgos, "diffie-hellman-group-exchange-sha1")
+	supportedKexAlgos = util.Remove(supportedKexAlgos, "diffie-hellman-group-exchange-sha256")
+	for _, m := range c.Moduli {
+		m = strings.TrimSpace(m)
+		if !util.IsFileInputValid(m) {
+			logger.Warn(logSender, "", "unable to load invalid moduli file %q", m)
+			logger.WarnToConsole("unable to load invalid host moduli file %q", m)
+			continue
+		}
+		if !filepath.IsAbs(m) {
+			m = filepath.Join(configDir, m)
+		}
+		logger.Info(logSender, "", "loading moduli file %q", m)
+		if err := ssh.ParseModuli(m); err != nil {
+			return err
+		}
+		supportedKexAlgos = append(supportedKexAlgos, "diffie-hellman-group-exchange-sha1",
+			"diffie-hellman-group-exchange-sha256")
+	}
+	return nil
+}
+
 // If no host keys are defined we try to use or generate the default ones.
 func (c *Configuration) checkAndLoadHostKeys(configDir string, serverConfig *ssh.ServerConfig) error {
 	if err := c.checkHostKeyAutoGeneration(configDir); err != nil {
@@ -853,14 +886,14 @@ func (c *Configuration) checkAndLoadHostKeys(configDir string, serverConfig *ssh
 	for _, hostKey := range c.HostKeys {
 		hostKey = strings.TrimSpace(hostKey)
 		if !util.IsFileInputValid(hostKey) {
-			logger.Warn(logSender, "", "unable to load invalid host key %#v", hostKey)
-			logger.WarnToConsole("unable to load invalid host key %#v", hostKey)
+			logger.Warn(logSender, "", "unable to load invalid host key %q", hostKey)
+			logger.WarnToConsole("unable to load invalid host key %q", hostKey)
 			continue
 		}
 		if !filepath.IsAbs(hostKey) {
 			hostKey = filepath.Join(configDir, hostKey)
 		}
-		logger.Info(logSender, "", "Loading private host key %#v", hostKey)
+		logger.Info(logSender, "", "Loading private host key %q", hostKey)
 
 		privateBytes, err := os.ReadFile(hostKey)
 		if err != nil {

internal/sftpd/sftpd_test.go

@@ -401,6 +401,12 @@ func TestInitialization(t *testing.T) {
 	assert.True(t, sftpdConf.Bindings[0].HasProxy())
 	err = sftpdConf.Initialize(configDir)
 	assert.Error(t, err)
+	sftpdConf.Moduli = []string{"missing moduli file"}
+	err = sftpdConf.Initialize(configDir)
+	if assert.Error(t, err) {
+		assert.Contains(t, err.Error(), "unable to open moduli file")
+	}
+	sftpdConf.Moduli = nil
 	sftpdConf.HostKeys = []string{"missing key"}
 	err = sftpdConf.Initialize(configDir)
 	assert.Error(t, err)

internal/util/util.go

@@ -125,6 +125,18 @@ func Contains[T comparable](elems []T, v T) bool {
 	return false
 }
 
+// Remove removes an element from a string slice and
+// returns the modified slice
+func Remove(elems []string, val string) []string {
+	for idx, v := range elems {
+		if v == val {
+			elems[idx] = elems[len(elems)-1]
+			return elems[:len(elems)-1]
+		}
+	}
+	return elems
+}
+
 // IsStringPrefixInSlice searches a string prefix in a slice and returns true
 // if a matching prefix is found
 func IsStringPrefixInSlice(obj string, list []string) bool {

sftpgo.json

@@ -84,6 +84,7 @@
     "host_keys": [],
     "host_certificates": [],
     "host_key_algorithms": [],
+    "moduli": [],
     "kex_algorithms": [],
     "ciphers": [],
     "macs": [],