[Swan] Centos7 Libreswan to cisco ipsec with sourceNAT?
frank at dio.demon.nl
Mon May 9 08:01:02 UTC 2016
I’m trying to setup an ipsec connection from a recent centos7 box to a cisco ASA.
Libreswan Version 3.15 XFRM(netkey) on 3.10.0-327.10.1.el7.x86_64
The remote/right side already has same internal range (192.168.1.0/24) present in their network for other purposes and also NATted this network for another party/purpose.
What I would like is to sourceNAT my traffic as to be coming from a ‘fake’, virtual ip range or address (say, 10.27.89.0/24), the that the right/remote only sees this 10.27.89.0/24 traffic & can route accordingly.
Is this possible / how to configure this with libreswan?
Can’t use KLIPS for ‘easier debug/tcpdump’, the centos is a stock image, can’t recompile the kernel/find the klips kernel module.
Are specific iptables rules needed for the sourceNAT?
How to go about debugging this ?
For OpenBSD ipsec/pf, this works like this (to another cisco party, I must use centos7/libreswan here):
ike esp from 10.27.89.34 (192.168.1.0/24) to <their_internal_ip_network> peer <their_internet_gateway_ip> main auth hmac-sha2-256 enc aes-256 group modp1024 lifetime 28800 quick auth hmac-sha2-256 enc aes-256 group modp1024 lifetime 28800 psk <presharedkey>
the from ip is virtual, my internal net between brackets
match out on enc0 from 192.168.1.0/24 to <their_internal_ip_network> nat-to 10.27.89.34
Remote net only sees traffic as if coming from ip 10.27.89.34
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