This article explains how to get xl2tpd, which has PPPtP cababilibies, working on Linux. This is useful where you have a server environment and you might need to connect from one server to another server.
If you’re using a Linux desktop based on Ubuntu, e.g. Linux Mint, you can use the built-in network manager to connect to a VPN. If you want to use the command line to connect to a desktop based-in VPN, use this command (see reference here):
nmcli con up id ConnectionName
Note password stored in clear text, so not secure.
ssh to server or use localhost
sudo -i
apt-get install -y xl2tpd ppp
or
yum install xl2tpd ppp
mv /etc/xl2tpd/xl2tpd.conf /etc/xl2tpd/xl2tpd.conf.backup
vi /etc/xl2tpd/xl2tpd.conf
When done:
# cat /etc/xl2tpd/xl2tpd.conf [lac myvpn] name = l2tp_user_name lns = l2tp_server_domain_or_ip pppoptfile = /etc/ppp/peers/myvpn.xl2tpd ppp debug = no
vi /etc/ppp/peers/myvpn.xl2tpd
[email protected]:~# cat /etc/ppp/peers/myvpn.xl2tpd remotename myvpn user "username" password "secret" unit 0 nodeflate nobsdcomp noauth persist nopcomp noaccomp maxfail 5 debug
Start the service. If you change credentials or all new files, restart the service:
systemctl start xl2tpd
Now connect:
sh -c 'echo "c myvpn" > /var/run/xl2tpd/l2tp-control'
Table of Contents
Troubleshooting tips?
Do `ifconfig` or ip addr and look for pppo0
Checking the log file
tail -f /var/log/syslog | grep pppd
How to add a VPN route
route add -host 192.168.8.20 dev ppp0
Errors
Unauthorized remote IP address
Feb 10 16:28:53 host01 pppd[1038040]: rcvd [IPCP TermReq id=0x2 "Unauthorized remote IP address"]
Check noipdefault
cat /etc/ppp/options
Look for this and possibly uncomment:
# Disables the default behaviour when no local IP address is specified, # which is to determine (if possible) the local IP address from the # hostname. With this option, the peer will have to supply the local IP # address during IPCP negotiation (unless it specified explicitly on the # command line or in an options file). #noipdefault
Checking remote username and password
Log into the remote VPN server and check your IP address and username:
cat /etc/ppp/chap-secrets
Just one connection allowed
Your L2TP might only allow one connection. Disconnect first and try again.
Route not found
When you do this:
# route add -host 172.168.1.42 dev ppp0
Command ‘route’ not found, but can be installed with:
apt install net-tools