set PATH correctly in ssh sessions

for a non=interactive shell ("ssh linminix foo") ash does not source
*any* startup files, so we need to set this to something more useful
than /bin:usr/bin

examples/rotuer.nix

@@ -151,12 +151,21 @@ in rec {
 
   services.sshd = longrun {
     name = "sshd";
+    # env -i clears the environment so we don't pass anything weird to
+    # ssh sessions. Dropbear params are
+    # -e  pass environment to child
+    # -E  log to stderr
+    # -R  create hostkeys if needed
+    # -P  pid-file
+    # -F  don't fork into background
+
     run = ''
       if test -d /persist; then
         mkdir -p /persist/secrets/dropbear
         ln -s /persist/secrets/dropbear /run
       fi
-      ${dropbear}/bin/dropbear -E -R -P /run/dropbear.pid  -F
+      PATH=${lib.makeBinPath config.defaultProfile.packages}:/bin
+      exec env -i ENV=/etc/ashrc PATH=$PATH ${dropbear}/bin/dropbear -e -E -R -P /run/dropbear.pid  -F
     '';
   };