free IPSec VPN client, works with IPCOP?

I see OpenVPN is a great tool...and is SSL. =/
I'm using IPCOP as the VPN server, and evidently it only works with
IPSec for VPN.

I see there are a lot of for pay IPSec VPN clients...I'm not finding
any free/open versions (maybe it's not possible. But since the SERVER
is evidently open-able, since IPCOP is free....)

Anyway, anyone have any recommendations? Is we HAVE to buy a VPN
client, I guess we can. If so, any recommendations of any that work
reliably with IPCOP?

Thanks!
Liam