How to redirect all 404s to the same path on a different server

Question

I want to redirect all 404 errors on my site to the same path on a different server.

For example:

http://drupal.example.com/url/not/in/drupal should be redirected to http://othersite.example.com/url/not/in/drupal

The sites are not on the same server and the other site is not running Drupal.

I know I can use the redirect module to redirect specific URLs but I don't have a complete list of the URLs on the other site so building the list is not practical.

Suggestions for modules or pointers to the appropriate hooks if I want to write my own module would be appreciated.

Answer 1

Here is small trick:

Enable module PHP Filter, add PHP filter to administrator

Create a node can use php filter, add code: (We are using header here, not use drupal_goto because handle 404 workfollow of Drupal will redirect to the node first.

<?php
  $url = drupal_get_destination();
  header('Location: http://other.example.com/' . $url['destination']);
  drupal_exit();
?>

Config Drupal using 404 page is the node you was create.