Example redis.conf binds just to 127.0.0.1.

It's hard to pick a good approach here. A few arguments:

1) There are many exposed instances on the internet.
2) Changing the default when "bind" is not given is very dangerous,
   after an upgrade the server changes a fundamental behavior.
3) Usually Redis, when used in a proper way, will be protected *and*
   accessed often from other computers, so this new default is likely
   not what most people want.
4) However if users end with this default, they are using the example
   redis.conf: likely they are reading what is inside, and they'll see
   the warning.

redis.conf

@@ -30,26 +30,27 @@
 # include /path/to/local.conf
 # include /path/to/other.conf
 
-################################ GENERAL  #####################################
+################################## NETWORK #####################################
 
-# By default Redis does not run as a daemon. Use 'yes' if you need it.
-# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
-daemonize no
-
-# If you run Redis from upstart or systemd, Redis can interact with your
-# supervision tree. Options:
-#   supervised no      - no supervision interaction
-#   supervised upstart - signal upstart by putting Redis into SIGSTOP mode
-#   supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
-#   supervised auto    - detect upstart or systemd method based on
-#                        UPSTART_JOB or NOTIFY_SOCKET environment variables
-# Note: these supervision methods only signal "process is ready."
-#       They do not enable continuous liveness pings back to your supervisor.
-supervised no
-
-# When running daemonized, Redis writes a pid file in /var/run/redis.pid by
-# default. You can specify a custom pid file location here.
-pidfile /var/run/redis.pid
+# By default, if no "bind" configuration directive is specified, Redis listens
+# for connections from all the network interfaces available on the server.
+# It is possible to listen to just one or multiple selected interfaces using
+# the "bind" configuration directive, followed by one or more IP addresses.
+#
+# Examples:
+#
+# bind 192.168.1.100 10.0.0.1
+# bind 127.0.0.1 ::1
+#
+# ~~~ WARNING ~~~ If the computer running Redis is directly exposed to the
+# internet, binding to all the interfaces is dangerous and will expose the
+# instance to everybody on the internet. So by default we uncomment the
+# following bind directive, that will force Redis to listen only into
+# the IPv4 lookback interface address (this means Redis will be able to
+# accept connections only from clients running into the same computer it
+# is running).
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+bind 127.0.0.1
 
 # Accept connections on the specified port, default is 6379.
 # If port 0 is specified Redis will not listen on a TCP socket.
@@ -64,16 +65,8 @@ port 6379
 # in order to get the desired effect.
 tcp-backlog 511
 
-# By default Redis listens for connections from all the network interfaces
-# available on the server. It is possible to listen to just one or multiple
-# interfaces using the "bind" configuration directive, followed by one or
-# more IP addresses.
+# Unix socket.
 #
-# Examples:
-#
-# bind 192.168.1.100 10.0.0.1
-# bind 127.0.0.1
-
 # Specify the path for the Unix socket that will be used to listen for
 # incoming connections. There is no default, so Redis will not listen
 # on a unix socket when not specified.
@@ -100,6 +93,27 @@ timeout 0
 # A reasonable value for this option is 60 seconds.
 tcp-keepalive 0
 
+################################# GENERAL #####################################
+
+# By default Redis does not run as a daemon. Use 'yes' if you need it.
+# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
+daemonize no
+
+# If you run Redis from upstart or systemd, Redis can interact with your
+# supervision tree. Options:
+#   supervised no      - no supervision interaction
+#   supervised upstart - signal upstart by putting Redis into SIGSTOP mode
+#   supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
+#   supervised auto    - detect upstart or systemd method based on
+#                        UPSTART_JOB or NOTIFY_SOCKET environment variables
+# Note: these supervision methods only signal "process is ready."
+#       They do not enable continuous liveness pings back to your supervisor.
+supervised no
+
+# When running daemonized, Redis writes a pid file in /var/run/redis.pid by
+# default. You can specify a custom pid file location here.
+pidfile /var/run/redis.pid
+
 # Specify the server verbosity level.
 # This can be one of:
 # debug (a lot of information, useful for development/testing)