Openvpn – Forwarding OpenVPN traffic on specific port to different OpenVPN server

I don't think that there is a way to explicitly invalidate cached items, but here is an example of how to do the rest. Update: As mentioned by Piotr in another answer, there is a cache purge module that you can use. You can also force a refresh of a cached item using nginx's proxy_cache_bypass - see Cherian's answer for more information.

In this configuration, items that aren't cached will be retrieved from example.net and stored. The cached versions will be served up to future clients until they are no longer valid (60 minutes).

Your Cache-Control and Expires HTTP headers will be honored, so if you want to explicitly set an expiration date, you can do that by setting the correct headers in whatever you are proxying to.

There are lots of parameters that you can tune - see the nginx Proxy module documentation for more information about all of this including details on the meaning of the different settings/parameters: http://nginx.org/r/proxy_cache_path

http {
  proxy_cache_path  /var/www/cache levels=1:2 keys_zone=my-cache:8m max_size=1000m inactive=600m;
  proxy_temp_path /var/www/cache/tmp; 


  server {
    location / {
      proxy_pass http://example.net;
      proxy_cache my-cache;
      proxy_cache_valid  200 302  60m;
      proxy_cache_valid  404      1m;
    }
  }
}

Postfix is extremely flexible (and therefore, complex) in its configuration, so there are various ways to achieve this. The simplest way would probably be to use a transport(5) table.

First, enable the use of a transport table in postfix:

/etc/postfix/main.cf:
    transport_maps = hash:/etc/postfix/transport

You'll also have to make sure that Postfix accepts mails for the addresses that will be handled by Lamson. Have a look at permit_auth_destination for the rules Postfix will apply to determine valid recipient addresses. For the following example, assuming "example.com" is a domain not otherwise known to Postfix, it's probably easiest to simply add it as relay domain:

/etc/postfix/main.cf:
    relay_domains = example.com

Then, create an appropriate table. E.g. to redirect all mail for the domain "example.com" as well as mail for "user@mydomain.org" to your local Lamson listening at port 10025:

/etc/postfix/transport:
    example.com          smtp:127.0.0.1:10025
    user@mydomain.org    smtp:127.0.0.1:10025

After that (and then once after every update to the transport table file) don't forget to run:

$ postmap /etc/postfix/transport

This should get you going. Be sure to read the transport(5) man page, which will give you more ideas on how to use this powerful facility.