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.
Yes, piece of cake!
Your WindowsXP box would need to become the default route for all your other computers. I do this often using a similar technique to tunnel traffic through an HTTP proxy firewall.
Couple things you need to do:
On your ubuntu server, locate the sshd.conf file and enable, if not already
GatewayPorts yes
Install Putty on your WinXP computer and configure a connection from WinXP to your Ubuntu server and under the Tunnels section, create some tunnel entries making sure to check the box "Local ports accept connections from other hosts", then use some random unprivledged ports. You should have a list like so:
L5000 1.2.3.4:443 where 5000 is the local port you listen on and 1.2.3.4 is your ubuntu server.
Now you need to enable Routing and Remote Access service under the services (right click My Computer, manage & navigate to services section). Once enabled, need to edit the following RegKey:
HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Services > Tcpip > Parameters and look for something like “IPEnableRouter”. Double click on it and turn the value from 0 to 1 and reboot your computer.
After the reboot, pop open a command prompt and type some commands:
netsh routing ip nat install
netsh routing ip nat add interface "if-public" full (where if-public is the interface used to connect to ubuntu server)
netsh routing ip nat add interface "if-private" private
It should be obvious that your WinXP machine cannot be using DHCP; you'll need static IP assignments here.
Best Answer
If outgoing connections are relatively open, you can ask
ssh(1)to create tunnels for you.Now, connections to
proxyserver.example.com:8888should be forwarded to your local port 80. The details from thessh(1)manpage: