The mission:

So the object here was to make Centos servers connect via L2TP to a Mikrotik LAC in order to provide connectivity with private ip’s.

This example will build a persistent L2TP tunnel which will auto reconnect and try to remain persistent.

On Mikrotik L2TP Server:

I used standard ppp profile in this example.

/ppp profile
set default change-tcp-mss=yes comment="" name=default only-one=default \
use-compression=default use-encryption=default use-vj-compression=default

Configured a secret in Mikrotik:

/ppp secret
add caller-id="" disabled=no limit-bytes-in=0 limit-bytes-out=0 local-address=10.0.0.1 name=MyUserName password=MyPassword profile=default \
remote-address=10.0.0.254 routes="" service=l2tp

On Mikrotik L2TP Server:

Install xl2tp from EPEL repo

yum install xl2tpd

Change /etc/xl2tpd/xl2tpd.conf

; This is a minimal sample xl2tpd configuration file for use as L2TP client.
;
[global]
debug tunnel = yes

[lac vpnserver]
lns = yourserverip
ppp debug = yes
pppoptfile = /etc/ppp/options.xl2tpd.client
length bit = yes
redial = yes
redial timeout = 2
autodial = yes

create or edit if exists /etc/ppp/options.xl2tpd.client

ipcp-accept-local
ipcp-accept-remote
refuse-eap
require-mschap-v2
noccp
noauth
idle 1800
mtu 1410
mru 1410
nodefaultroute
debug
lock
connect-delay 5000
name MyUserName
password MyPassword
persist
maxfail 0

Create file: /etc/ppp/ip-up.local and remember to chmod +x ….

#!/bin/sh
# Where 10.0.0.1 is the Tunnel endpoint IP defined on Mikrotik or Linux LAC  
case  in
        10.0.0.1)
        # VPN - IP ROUTE BEING ADDED AT RECONNECTION
                route add -net 10.0.0.0/24 gw 10.0.0.1;
        ;;
esac

Now start xl2tpd..

/etc/init.d/xl2tpd start

Result: ifconfig….

[root@myserv ~]# ifconfig ppp0
ppp0      Link encap:Point-to-Point Protocol
          inet addr:10.0.0.254  P-t-P:10.0.0.1  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1410  Metric:1
          RX packets:1198 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1260 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:156001 (152.3 KiB)  TX bytes:1144669 (1.0 MiB)

 

A Snippet of the routing table…

[root@myserv ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.254.255.1    0.0.0.0         255.255.255.255 UH    0      0        0 ppp0
10.254.255.0    10.254.255.1    255.255.255.0   UG    0      0        0 ppp0