Home / Open source / Linux / Configurer un VPN L2TP / IPSec sur Ubuntu (15.10 & 16.04) pour Fortigate (Forti OS 5.2)

Configurer un VPN L2TP / IPSec sur Ubuntu (15.10 & 16.04) pour Fortigate (Forti OS 5.2)

After hours on google and my Ubuntu working VMs, I found a solutions to establish the VPN tunnel to my office datacenter. Something that should very easy and simple to do with other devices and OSs (Android, iOS, Windows 10) it is very hard with Ubuntu (Very strange Non ?) !! As Jason’s blog report « Unfortunately as many people likely know (after a few google searches it seems) the client for this is pretty crap in Ubuntu 16.04.  » And I confirm.
Here is a small howto configure your VPN to a Fortigate 90D (FortiOs 5.2) with Ubuntu 15.10 Wily Werewolf or Ubuntu 16.04 LTS Xenial Xerus.

To check your Ubuntu version :

lsb_release -a

Configure On-demand tunnel using native L2TP/IPSec on your FortiGate

The latest Fortigate firewall/routers comes with  some templates for creating VPN Tunnels. We should use  » Dialup – Android (Native L2TP/IPsec) » to get Ubuntu users connected.
I tried the « Dialup – Cisco Firewall » that should work with vpnc packages but nothing works fine !!.
Here is a sample wizard to create your VPN tunnel :

  1. Create a User group « VPN Users » for users that they should establish the VPN connection.
    fortigateusergroup
  2. Create local user or synchronize them from your remote active directory and attach them to « VPN Users ». For manually configuration (First solution) you should not use special characters ($ & ..) in the password.
  3. Create the tunnel template as presented in secreen shots
    1. Step 1 : VPN Setup
      fortigatecreatevpn-step1
    2. Step 2 : Authentication
      fortigatecreatevpn-step2
    3. Step 3 : Policy & Routing
      fortigatecreatevpn-step3
  4. Note the tunnel template detail by clicking on the template name from the tunnel lis :
    fortigatetemplatedetails
  5. You should also note :
    1. Public IP address
    2. Preshared key
    3. Username and Password

Solution 1 : Manual configuration using strongswan xl2tpd packages

I followed Jason’s ticket : http://www.jasonernst.com/2016/06/21/l2tp-ipsec-vpn-on-ubuntu-16-04/. This solution works fine on Ubuntu 15.10 and 16.04

  1. Install required packages
    sudo apt-get install -y strongswan xl2tpd
  2. Create / Edit the ipsec.conf file
    sudo vi /etc/ipsec.conf
    # ipsec.conf - strongSwan IPsec configuration file
    # basic configuration
    config setup
    #     strictcrlpolicy=yes
    #     uniqueids = no
    # Add connections here.
    # Sample VPN connections
    conn %default
         ikelifetime=60m
         keylife=20m
         rekeymargin=3m
         keyingtries=1
         keyexchange=ikev1
         authby=secret
         ike=aes256-md5-modp1024,3des-sha1-modp1024!
    # esp=aes256-md5-modp1024,3des-sha1-modp1024!
    conn XXX-YOUR-CONNECTION-NAME-XXX
         keyexchange=ikev1
         left=%defaultroute
         auto=add
         authby=secret
         type=transport
         leftprotoport=17/1701
         rightprotoport=17/1701
    # set this to the ip address of your vpn server
         right=FIREWALL_PUBLIC_IP
    

    Note my modifications in bold to be able to negociate DH phase 1 & 2 algorithm and hash with our Fortigate VPN tunnel specifications.

  3. Put the preshared key in ipsec.secrets
    sudo nano /etc/ipsec.secrets
    : PSK "YOUR_PSK_GOES_HERE"
    
  4. Setup the xl2tpd.conf
    sudo vi /etc/xl2tpd/xl2tpd.conf
    [lac XXX-YOUR-CONNECTION-NAME-XXX]
    lns = FIREWALL_PUBLIC_IP
    ppp debug = yes
    pppoptfile = /etc/ppp/options.l2tpd.client
    length bit = yes
    
  5. Setup the ppp configuration
    sudo vi /etc/ppp/options.l2tpd.client
    ipcp-accept-local
    ipcp-accept-remote
    refuse-eap
    require-mschap-v2
    noccp
    noauth
    idle 1800
    mtu 1410
    mru 1410
    defaultroute
    usepeerdns
    debug
    lock
    connect-delay 5000
  6. Create run file and path for xl2tp
    sudo mkdir -p /var/run/xl2tpd
    sudo touch /var/run/xl2tpd/l2tp-control
  7. Restart Services
    sudo service strongswan restart
    sudo service xl2tpd restart
  8. Bring up the l2tp tunnel interface
    sudo ipsec up XXX-YOUR-CONNECTION-NAME-XXX

    you should have something like this on output.

    initiating Main Mode IKE_SA XXX-YOUR-CONNECTION-NAME-XXX[1] to FIREWALL_PUBLIC_IP
    generating ID_PROT request 0 [ SA V V V V ]
    sending packet: from 192.168.1.64[500] to FIREWALL_PUBLIC_IP[500] (188 bytes)
    received packet: from FIREWALL_PUBLIC_IP[500] to 192.168.1.64[500] (144 bytes)
    parsed ID_PROT response 0 [ SA V V V ]
    received NAT-T (RFC 3947) vendor ID
    received DPD vendor ID
    received unknown vendor ID: 82:99:03:17:57:a3:60:82:c6:a6:21:de:00:05:02:e0
    generating ID_PROT request 0 [ KE No NAT-D NAT-D ]
    sending packet: from 192.168.1.64[500] to FIREWALL_PUBLIC_IP[500] (236 bytes)
    received packet: from FIREWALL_PUBLIC_IP[500] to 192.168.1.64[500] (220 bytes)
    parsed ID_PROT response 0 [ KE No NAT-D NAT-D ]
    local host is behind NAT, sending keep alives
    generating ID_PROT request 0 [ ID HASH ]
    sending packet: from 192.168.1.64[4500] to FIREWALL_PUBLIC_IP[4500] (76 bytes)
    received packet: from FIREWALL_PUBLIC_IP[4500] to 192.168.1.64[4500] (76 bytes)
    parsed ID_PROT response 0 [ ID HASH ]
    IKE_SA XXX-YOUR-CONNECTION-NAME-XXX[1] established between 192.168.1.64[192.168.1.64]...FIREWALL_PUBLIC_IP[FIREWALL_PUBLIC_IP]
    scheduling reauthentication in 3247s
    maximum IKE_SA lifetime 3427s
    generating QUICK_MODE request 111451902 [ HASH SA No ID ID NAT-OA NAT-OA ]
    sending packet: from 192.168.1.64[4500] to FIREWALL_PUBLIC_IP[4500] (252 bytes)
    received packet: from FIREWALL_PUBLIC_IP[4500] to 192.168.1.64[4500] (172 bytes)
    parsed QUICK_MODE response 111451902 [ HASH SA No ID ID NAT-OA NAT-OA ]
    connection 'XXX-YOUR-CONNECTION-NAME-XXX' established successfully
    
  9. Authenticate using your username & password
    sudo bash -c "echo \"c XXX-YOUR-CONNECTION-NAME-XXX username password\" > /var/run/xl2tpd/l2tp-control"
  10. Now you should have a ppp interface up
    ifconfig
    ppp0 Link encap:Point-to-Point Protocol
    inet addr:192.168.202.2 P-t-P:192.168.202.1 Mask:255.255.255.255
    UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1410 Metric:1
    RX packets:7 errors:0 dropped:0 overruns:0 frame:0
    TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:3
    RX bytes:283 (283.0 B) TX bytes:256 (256.0 B)
    
  11. At this moment you should contact any server in your office datacenter. however if you want that all your internet traffic pass in the vpn tunnel you should add this routes :
    1. note the local gateway :
      route
      Kernel IP routing table
      Destination Gateway Genmask Flags Metric Ref Use Iface
      default 192.168.1.254 0.0.0.0 UG 0 0 0 eth0
      link-local * 255.255.0.0 U 1000 0 0 eth0
      172.17.0.0 * 255.255.0.0 U 0 0 0 docker0
      172.26.0.0 * 255.255.0.0 U 100 0 0 eth2
      192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
      192.168.200.0 * 255.255.255.0 U 0 0 0 ppp0
      192.168.202.1 * 255.255.255.255 UH 0 0 0 ppp0
      

      => your local default gateway is 192.168.1.254
      => your vpn local gateway ip is 192.168.202.1

    2. Add route to the FIREWALL_PUBLIC_IP
      sudo route add FIREWALL_PUBLIC_IP gw LOCAL_DEFAULT_GATEWAY
    3. Add default route
      sudo route add -net default gw VPN_GATEGOAY
    4. You can check your outgoing ip with http://www.mon-ip.com you should got your office ip address or
      $ curl http://ipinfo.io
      {
        "ip": "AA.BB.CC.DD",
        "city": "Amsterdam",
        "region": "North Holland",
        "country": "NL",
        "loc": "52.3556,4.9135",
        "postal": "1091",
        "org": "AS8075 Microsoft Corporation"
      }
      
  12. To release the tunnel you should
    1. Shutdhown the tunnel
      sudo ipsec down FIREWALL_PUBLIC_IP
    2. Restart services again
      sudo service strongswan restart
      sudo service xl2tpd restart

Issues

Solution 2 : GUI Network Manager

As reported http://blog.z-proj.com/enabling-l2tp-over-ipsec-on-ubuntu-16-04/ Ubuntu has stopped shipping L2TP on IPSec since Precise (12.04.x LTS). Here is the work around but it works only on Ubuntu 16.04.

  1. Install Prerequist packages :
    sudo apt install \
    intltool \
    libtool \
    network-manager-dev \
    libnm-util-dev \
    libnm-glib-dev \
    libnm-glib-vpn-dev \
    libnm-gtk-dev \
    libnm-dev \
    libnma-dev \
    ppp-dev \
    libdbus-glib-1-dev \
    libsecret-1-dev \
    libgtk-3-dev \
    libglib2.0-dev \
    xl2tpd \
    strongswan
  2. Build the network-manager-l2tp for its git repository
    git clone https://github.com/nm-l2tp/network-manager-l2tp.git
    cd network-manager-l2tp
    autoreconf -fi
    intltoolize
    
  3. Pray to not have any errors
  4. Configure the build : Change path that not correspond to your installation
    ./configure \
    --disable-static --prefix=/usr \
    --sysconfdir=/etc --libdir=/usr/lib/x86_64-linux-gnu \
    --libexecdir=/usr/lib/NetworkManager \
    --localstatedir=/var \
    --with-pppd-plugin-dir=/usr/lib/pppd/2.4.7
  5. Install the package :
    make
    sudo make install
    
  6. Remove AppArmor setting for IPSec
    sudo apparmor_parser -R /etc/apparmor.d/usr.lib.ipsec.charon
    sudo apparmor_parser -R /etc/apparmor.d/usr.lib.ipsec.stroke 
  7. Replace xl2tpd with libcap
    sudo apt remove xl2tpd
    sudo apt install libpcap0.8-dev
    
    wget https://github.com/xelerance/xl2tpd/archive/v1.3.6/xl2tpd-1.3.6.tar.gz
    tar xvzf xl2tpd-1.3.6.tar.gz
    cd xl2tpd-1.3.6
    make
    sudo make install
  8. Restart you machine
  9. You can now start configure your VPN Tunnel with the nm-connection-editor application. You should have a new option for vpn
    1. networkmanager-screen0
    2. networkmanager-screen1
    3. networkmanager-screen2
    4. networkmanager-screen3

Good home working 😉

 

Helpful links

http://www.jasonernst.com/2016/06/21/l2tp-ipsec-vpn-on-ubuntu-16-04/

http://blog.z-proj.com/enabling-l2tp-over-ipsec-on-ubuntu-16-04/

http://packages.ubuntu.com/search?keywords=libnma-dev

http://askubuntu.com/questions/617785/how-to-connect-to-l2tp-over-ipsec-vpn

https://github.com/nm-l2tp/network-manager-l2tp

https://fr.ikoula.wiki/fr/Mettre_en_place_un_VPN_L2TP/IPSEC

https://supportforums.cisco.com/document/12276506/diffie-hellman-groups

https://doc.pfsense.org/index.php/IPsec_Troubleshooting

http://cookbook.fortinet.com/ipsec-vpn-troubleshooting/

https://gist.github.com/psanford/42c550a1a6ad3cb70b13e4aaa94ddb1c
http://stackoverflow.com/questions/82256/how-do-i-use-sudo-to-redirect-output-to-a-location-i-dont-have-permission-to-wr

About Wicem

Check Also

Configurer Jenkins pour PHP

Here a summary of steps and instructions for preparing a continuous integration platform for PHP …

4 comments

  1. Hi, I need a L2TP/IPSec VPN software which can be installed in ubuntu 16.10.
    Do you think strongswan xl2tpd packages is compatible for this version of ubuntu 16.10?
    if yes then Is it free ware software?
    If no, can you suggest me any other VPN software options??

    Thanks
    Munim Morshed

    • Thank you for your comment and question. As you see, those packages à available for ubuntu repository so they are free. I’ve also tried some GUI packages but I got some issues.
      If you find something else please keep me in touch.
      Best regards

  2. Thank you man, very helpful!
    Your solution 1 works fine on Kubuntu 16.10.
    In my case, I should also add:
    leftnexthop=%defaultroute
    rightnexthop=%defaultroute
    rightid=%any
    to ipsec.conf to custom connection properties. (I don’t exactly know what that properties mean)

    Additional implicit notes:
    1. Keep indents in ipsec.conf
    2. Use « journalctl -xe » to watch any network errors you can encounter.

Laisser un commentaire

Votre adresse de messagerie ne sera pas publiée. Les champs obligatoires sont indiqués avec *