🥇IPSec tunnel between Strongswan behind NAT and VMWare NSX Edge

For a number of reasons, it was necessary to establish a VPN connection between the network in VMWare Cloud Director and a separate Ubuntu machine in the cloud. The note does not pretend to be a full description, it's just a small howto.

The only article of 2015 on this topic was found on the network "Site to Site IPSEC VPN between NSX Edge and Linux strongSwan».

Unfortunately, it was not possible to use it directly, because. I wanted more reliable encryption, not a self-signed certificate, and the described config would not work behind NAT.

Therefore, I had to sit down and delve into the documentation.

As a basis, I took the config that I have been using for a long time, which allows you to connect from almost any OS, and simply added a piece to it that allows you to connect to NSX Edge.

Since the installation and full configuration of the Strongswan server is beyond the scope of the note, let me refer to good stuff on the subject.

So, let's go directly to the settings.

Our connection diagram will look like this:

со стороны VMWare внешний адрес 33.33.33.33 и внутренняя сеть 192.168.1.0/24
со стороны Linux внешний адрес 22.22.22.22 и внутренняя сеть 10.10.10.0/24
также понадобится настроить Let's encrypt сертификат для адреса vpn.linux.ext
PSK с обеих сторон: ChangeMeNow!

Setting by NSX Edge:

Text

Enabled: yes
Enable perfect forward secrecy (PFS): yes
Name: VPN_strongswan (любое, по вашему выбору)
Local Id: 33.33.33.33
Local Endpoint: 33.33.33.33
Local Subnets: 192.168.1.0/24
Peer Id: vpn.linux.ext
Peer Endpoint: 22.22.22.22
Peer Subnets: 10.10.10.0/24
Encryption Algorithm: AES256
Authentication: PSK
Pre-Shared Key: ChangeMeNow!
Diffie-Hellman Group: 14 (2048 bit — приемлемый компромисс между скоростью и безопасностью. Но если хотите, можете поставить больше)
Digest Algorithm: SHA256
IKE Option: IKEv2
IKE Responder Only: no
Session Type: Policy Based Session

Screenshots

Setting by Strongswan:

ipsec.conf

# /etc/ipsec.conf
config setup

conn %default
	dpdaction=clear
	dpddelay=35s
	dpdtimeout=300s

	fragmentation=yes
	rekey=no

	ike=aes256gcm16-aes256gcm12-aes128gcm16-aes128gcm12-sha256-sha1-modp2048-modp4096-modp1024,aes256-aes128-sha256-sha1-modp2048-modp4096-modp1024,3des-sha1-modp1024!
	esp=aes128gcm12-aes128gcm16-aes256gcm12-aes256gcm16-modp2048-modp4096-modp1024,aes128-aes256-sha1-sha256-modp2048-modp4096-modp1024,aes128-sha1-modp2048,aes128-sha1-modp1024,3des-sha1-modp1024,aes128-aes256-sha1-sha256,aes128-sha1,3des-sha1!

	left=%any
	leftsubnet=10.10.10.0/24
        leftcert=certificate.pem
	leftfirewall=yes
	leftsendcert=always

	right=%any
	rightsourceip=192.168.1.0/24
	rightdns=77.88.8.8,8.8.4.4

	eap_identity=%identity

# IKEv2
conn IPSec-IKEv2
	keyexchange=ikev2
	auto=add

# BlackBerry, Windows, Android
conn IPSec-IKEv2-EAP
	also="IPSec-IKEv2"
	rightauth=eap-mschapv2

# macOS, iOS
conn IKEv2-MSCHAPv2-Apple
	also="IPSec-IKEv2"
	rightauth=eap-mschapv2
	leftid=vpn.linux.ext

# Android IPsec Hybrid RSA
conn IKEv1-Xauth
	keyexchange=ikev1
	rightauth=xauth
	auto=add

# VMWare IPSec VPN
conn linux-nsx-psk
	authby=secret
	auto=start
	leftid=vpn.linux.ext
	left=10.10.10.10
	leftsubnet=10.10.10.0/24
	rightid=33.33.33.33
	right=33.33.33.33
	rightsubnet=192.168.1.0/24
	ikelifetime=28800
	keyexchange=ikev2
	lifebytes=0
	lifepackets=0
	lifetime=1h

ipsec.secret

# /etc/ipsec.secrets
: RSA privkey.pem

# Create VPN users accounts
# ВНИМАНИЕ! После логина сначала пробел, потом двоеточие.

user1 : EAP "stongPass1"
user2 : EAP "stongPass2"
%any 33.33.33.33 : PSK "ChangeMeNow!"

after that, just re-read the config, start the connection and check that it is established:

ipsec update
ipsec rereadsecrets
ipsec up linux-nsx-psk
ipsec status

I hope this little note is helpful and saves someone a couple of hours.

Source: habr.com

IPSec tunnel between Strongswan behind NAT and VMWare NSX Edge

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