diff --git a/Lib.fs b/Lib.fs
index 0aeff4c074d87ef4d718f9ec771f9bcf1175e22a..704f633770b87ba8c152fe1de8455f1322a81b84 100644
--- a/Lib.fs
+++ b/Lib.fs
@@ -65,5 +65,14 @@ let toMingwPath (windowsPath: string) =
         windowsPath
   result
 
+// Convert Mingw64 path to windows path.
+let toWinPath (mingwPath: string) =
+  if mingwPath.StartsWith("/cygdrive/") then
+    let driveLetter = mingwPath.Substring("/cygdrive/".Length, 1).ToUpper()
+    let rest = mingwPath.Substring("/cygdrive/".Length + 1)
+    driveLetter + ":" + rest.Replace('/', '\\')
+  else
+    null
+
 let ensureDir (path: string) = if path.EndsWith "/" then path else path + "/"
 let ensureWinDir (path: string) = if path.EndsWith "\\" then path else path + "\\"
diff --git a/Program.fs b/Program.fs
index da0ef7193d8a2f91ad6011fdf5d6979ca03825ce..3acfbb5962e74b91e8baa6bc562a0f6d61f433b8 100644
--- a/Program.fs
+++ b/Program.fs
@@ -180,7 +180,12 @@ let main argv =
     let sshExeFile = mbackupProgramDir + "rsync-w64/usr/bin/ssh.exe"
     let sshConfigFile = userHome + ".ssh/config"
     let sshPrivateKeyFile = results.GetResult(Ssh_Key, defaultValue = userHome + ".ssh/id_rsa") |> toMingwPath
-    let rsyncCmd = List.append rsyncCmd [sprintf "-e \"'%s' -F %s -i %s -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null\"" sshExeFile sshConfigFile sshPrivateKeyFile]
+    let sshConfigFileOption =
+      if File.Exists(toWinPath sshConfigFile) then
+        " -F " + sshConfigFile
+      else
+        ""
+    let rsyncCmd = List.append rsyncCmd [sprintf "-e \"'%s'%s -i %s -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null\"" sshExeFile sshConfigFileOption sshPrivateKeyFile]
 
     // precedence: command line argument > environment variable > config file
     let normalizeTarget target =
diff --git a/mbackup-tests/MbackupTest.fs b/mbackup-tests/MbackupTest.fs
index 60db4676af511067305d40fd053f1f3166260e21..3b979e35c44cdaa949a3b8a47f5f57c353706c0a 100644
--- a/mbackup-tests/MbackupTest.fs
+++ b/mbackup-tests/MbackupTest.fs
@@ -27,6 +27,14 @@ let TesttoMingwPath () =
     Assert.That("/cygdrive/D/foo", Is.EqualTo(toMingwPath "/D/foo"))
     Assert.That("/var/log", Is.EqualTo(toMingwPath "/var/log"))
 
+[<Test>]
+let TesttoWinPath () =
+    Assert.That("C:\\abc\\def", Is.EqualTo(toWinPath "/cygdrive/c/abc/def"))
+    Assert.That("C:\\abc\\def\\", Is.EqualTo(toWinPath "/cygdrive/c/abc/def/"))
+    Assert.That("C:\\", Is.EqualTo(toWinPath "/cygdrive/c/"))
+    Assert.That("D:\\", Is.EqualTo(toWinPath "/cygdrive/d/"))
+    Assert.That(null, Is.EqualTo(toWinPath "/etc/foo/"))
+
 let mysprintf fmt = sprintf fmt
 
 [<Test>]
diff --git a/operational b/operational
index 87647fc9c23429bd2d087c6094fad905a3b81e31..1a59009c1f939cbaafe2248750714d3a98ef1265 100644
--- a/operational
+++ b/operational
@@ -194,6 +194,21 @@ Both local.list and local.exclude.
   - mbackup.msi works on B75I3 host.
   - try mbackup.msi on win 10 VM.
     how to require dotnet core 3.0 in .wxs file?
+    search: wix NetFxExtension symbol for .net core 3
+    asp.net mvc - Wix package ID for .NET core runtime 1.0.3 - Stack Overflow
+    https://stackoverflow.com/questions/42908913/wix-package-id-for-net-core-runtime-1-0-3
+    requires dotnet core 3 runtime on target node.
+    backup to local dir works.
+    backup to remote ssh node...
+    - problems
+      - 2019-11-14T10:50:13 ERROR Read/write file failed: System.Private.CoreLib Could not find a part of the path 'C:\Users\IEUser\AppData\Local\mbackup\mbackup.list'.
+        Does the dir exist? no. Create it at runtime.
+        fixed.
+      - backup to remote ssh node.
+        Warning: Identity file /cygdrive/c/Users/IEUser/.ssh/id_rsa not accessible: No such file or directory.
+        Can't open user config file /cygdrive/c/Users/IEUser/.ssh/config: No such file or directory
+        DONE do not specify config file if it doesn't exist.
+        TODO fail fast if ssh key doesn't exist. mbackup will only support key based auth.
 
 - problems
   - each file require it's own <Component> tag.