How to redirect all node aliases to ?
Using the Rules module you can implement a rule that looks like so:

{ "rules_redirect_all_node_aliases" : {
    "LABEL" : "Redirect all node aliases",
    "PLUGIN" : "reaction rule",
    "OWNER" : "rules",
    "REQUIRES" : [ "rules" ],
    "ON" : { "init" : [] },
    "IF" : [
      { "text_matches" : {
          "text" : [ "site:current-page:path" ],
          "match" : "node\/\\d+$",
          "operation" : "regex"
        }
      }
    ],
    "DO" : [
      { "redirect" : { "url" : "my_homepage" } }
    ]
  }
}


It will redirect any path starting with node/ to a path named my_homepage (adapt that path to fit your homepage path).

To experiment with this rule in your own site, just copy the entire Rules code above, and paste it in a new Rule in your own site, created via the "Import" function.

Note: A variation of this rule could be to replace the Rules Condition with something like "if the current path is not my_homepage" (in which case the same Rules Action will redirect to my_homepage.