.htaccess

RewriteEngine On
# 将404页面跳转到 http://abc.com/

ErrorDocument 404 http://abc.com/
# 将 不是abc.com 永久跳转到 http://abc.com
rewriteCond %{http_host} !^abc.com [NC]
rewriteRule ^(.*)$ http://abc.com/$1 [R=301,L]