OpenVPN Client Nat question?

[Fire walls]

  Hi people.

  Working with pf, every day I'm understanding more pf.

   I have openvpn at work running on gentoo, I add my openvpn in my home FW
with freebsd 7.2, I setup everything and is working, I can reach my work
network.

   I read some sites on internet about this setup and they say something
about NAT the openvpn network but doesn't explain if this must be done just
in the server side or both sides, I mean server + client.

   In my case I'm a client, I have to NAT my vpn network?

nat on $ext_if from $vpn_network to any -> ($ext_if)

   Or just need to play with the pass/block rules?

  Thanks all for your time!!!

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:-)