+# Allow using -M (ControlMaster) to create a master SSH session which
+# "tunnels" other connections to the same host, thus reducing the number of
+# authentications (which are relatively slow) and TCP connections. The master
+# sockets are stored in ~/.ssh (by default ControlPath is not set). Using %r
+# (remote user name) might leak information to other users on the current
+# system (e.g. via netstat or lsof).
+ ControlPath ~/.ssh/master-%l-%h-%p-%r
+# Automatically create a new master session if there's none yet or use an
+# existing one. This way the user doesn't have to use -M to enable a master
+# manually. Don't set this option to "yes" or all SSH commands try to become
+# the master session which is obviously not possible.
+ ControlMaster auto
+# When the connection for a master is closed (e.g. logout of remote shell),
+# move the master connection in the background. If there's no other active
+# connection using the master, close it after x seconds. This prevents the
+# client of the master connection from blocking because it waits for all
+# connections using it to terminate which is very annoying. The timeout
+# prevents stale master connections.
+ ControlPersist 10
+
+# Don't hash any hosts in ~/.ssh/known_hosts. It doesn't help if the ssh hosts
+# are stored in the shell's history file or in this file as shortcut so it's
+# rather useless (default).
+ HashKnownHosts no
+
+# Don't permit running local commands (default).
+ PermitLocalCommand no
+
+# Don't send any environment variables (default).