PPTP Client - ArchWiki

# PPTP Client

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- PPTP server

pptpclient is a program implementing the Microsoft PPTP protocol. As such, it can be used to connect to a Microsoft VPN network (or any PPTP-based VPN) provided by a school or workplace.

Warning: The PPTP protocol is inherently insecure. See http://poptop.sourceforge.net/dox/protocol-security.phtml for details.

## Installation

Install the pptpclient package.

## Configure

To configure pptpclient you will need to collect the following information from your network administrator:

- The IP address or hostname of the VPN server.
- The username you will use to connect.
- The password you will use to connect.
- The authentication (Windows) domain name. This is not necessary for certain networks.

You must also decide what to name the tunnel.

### Configure using pptpsetup

You can configure and delete tunnels by running the pptpsetup tool as root. For example:

    pptpsetup --create my_tunnel --server vpn.example.com --username alice --password foo --encrypt
    pptpsetup --delete my_tunnel

You can #Connect after a tunnel has been configured.

### Configure by hand

You can also edit all necessary configuration files by hand, rather than relying on pptpsetup.

#### Edit The options File

The `/etc/ppp/options` file sets security options for your VPN client. If you have trouble connecting to your network, you may need to relax the options. At a minimum, this file should contain the options `lock`, `noauth`, `nobsdcomp` and `nodeflate`.

    /etc/ppp/options

    # Lock the port
    lock
    # We don't need the tunnel server to authenticate itself
    noauth
    # Turn off compression protocols we know won't be used
    nobsdcomp
    nodeflate
    # We won't do PAP, EAP, CHAP, or MSCHAP, but we will accept MSCHAP-V2
    # (you may need to remove these refusals if the server is not using MPPE)
    refuse-pap
    refuse-eap
    refuse-chap
    refuse-mschap

#### Edit The chap-secrets File

The `/etc/ppp/chap-secrets` file contains credentials for authenticating a tunnel. Make sure no one except root can read this file, as it contains sensitive information.

    chmod 0600 /etc/ppp/chap-secrets

Edit the file. It has the following format:

    /etc/ppp/chap-secrets

    <DOMAIN>\\<USERNAME> PPTP <PASSWORD> *

Replace each bracketed term with an appropriate value. Omit `<DOMAIN>\\` if your connection does not require a domain.

Note: Place your password in double quotation marks (`"`) if it contains special characters such as `$`.
Warning: This file contains passwords in plain text. Guard it well!

#### Name Your Tunnel

The `/etc/ppp/peers/<TUNNEL>` file contains tunnel-specific configuration options. `<TUNNEL>` is the name you wish to use for your VPN connection. The file should look like this:

    /etc/ppp/peers/<TUNNEL>

    pty "pptp <SERVER> --nolaunchpppd"
    name <DOMAIN>\\<USERNAME>
    remotename PPTP
    require-mppe-128
    file /etc/ppp/options
    ipparam <TUNNEL>

Again, omit `<DOMAIN>\\` if your connection does not require a domain. `<SERVER>` is the remote address of the VPN server, `<DOMAIN>` is the domain your user belongs to, `<USERNAME>` is the name you will use to connect to the server, and `<TUNNEL>` is the name of the connection.

Note: `remotename PPTP` is used to find `<PASSWORD>` in the `/etc/ppp/chap-secrets` File.
Note: If you do not need MPPE support, you should remove the `require-mppe-128` option from this file and from `/etc/ppp/options`

## Connect

To make sure that everything is configured properly, as root execute:

    # pon <TUNNEL> debug dump logfd 2 nodetach

If everything has been configured correctly, the `pon` command should not terminate. Once you are satisfied that it has connected successfully, you can terminate the command.

Note: As an additional verification you can run `ip addr show` and ensure that a new device, `ppp0`, is available.

To connect to your VPN normally, simply execute:

    # pon <TUNNEL>

Where `<TUNNEL>` is the name of the tunnel you established earlier. Note that this command should be run as root.

### Routing

Once you have connected to your VPN, you should be able to interact with anything available on the VPN server. To access anything on the remote network, you need to add a new route to your routing table.

Note: Depending on your configuration, you may need to re-add the routing information every time you connect to your VPN.

For more information on how to add routes, you can read this article which has many more examples: PPTP Routing Howto

#### Split Tunneling

Packets with a destination of your VPN's network should be routed through the VPN interface (usually `ppp0`). To do this, you create the route:

    # ip route add 192.168.10.0/24 dev ppp0

This will route all the traffic with a destination of 192.168.10.* through your VPN's interface, (`ppp0`).

#### Route All Traffic

It may be desirable to route all traffic through your VPN connection. You can do this by running:

    # ip route add default dev ppp0

Note: Routing all traffic through the VPN may result in slower over all connection speed because your traffic will be routed through the remote VPN before being routed normally.

#### Route All Traffic by /etc/ppp/ip-up.d

Note: All scripts in `/etc/ppp/ip-up.d/` will called when the VPN connection is established.

    /etc/ppp/ip-up.d/01-routes.sh

    #!/bin/bash

    # This script is called with the following arguments:
    # Arg Name
    # $1 Interface name
    # $2 The tty
    # $3 The link speed
    # $4 Local IP number
    # $5 Peer IP number
    # $6 Optional ``ipparam'' value foo

    ip route add default via $4

Make sure the script is executable.

#### Split Tunneling based on port by /etc/ppp/ip-up.d

Note: All scripts in `/etc/ppp/ip-up.d/` will called when the VPN connection is established.

    /etc/ppp/ip-up.d/01-routebyport.sh

    #!/bin/bash

    # This script is called with the following arguments:
    # Arg Name
    # $1 Interface name
    # $2 The tty
    # $3 The link speed
    # $4 Local IP number
    # $5 Peer IP number
    # $6 Optional ``ipparam'' value foo

    echo 0 > /proc/sys/net/ipv4/conf/$1/rp_filter
    echo 1 > /proc/sys/net/ipv4/ip_forward
    echo 1 > /proc/sys/net/ipv4/ip_dynaddr

    ip route flush table vpn
    ip route add default via $5 dev $1 table vpn

    # forward only IRC ports over VPN
    iptables -t mangle -A OUTPUT -p tcp -m multiport --dports 6667,6697 -j MARK --set-mark 0x1
    iptables -t nat    -A POSTROUTING -o $1 -j MASQUERADE

    ip rule  add fwmark 0x1 pri 100 lookup vpn
    ip rule  add from $4 pri 200 table vpn
    ip route flush cache

Make sure the script is executable and that the vpn table is added to `/etc/iproute2/rt_tables`

    201 vpn

## Disconnect

Execute the following to disconnect from a VPN:

    # poff <TUNNEL>

`<TUNNEL>` is the name of your tunnel.

## Making A VPN Daemon and Connecting On Boot

This article or section is out of date.

Reason: recent changes to systemd. see https://wiki.archlinux.org/index.php/Systemd/Services (Discuss in Talk:PPTP Client#)

You can create a simple daemon for your VPN connection by creating an appropriate `/etc/rc.d/*` script:

Note: As always, `<TUNNEL>` is the name of your tunnel. `<ROUTING COMMAND>` is the command you use to add the appropriate route to the routing table.
Note: The stop functionality of this script will not work if the `updetach` and `persist` arguments are passed to `/usr/bin/pon` when pon is started. The reason for this is that the `/usr/bin/poff` script contains a bug when determining the PID of the specified `pppd` process if arguments were passed to `pon`.

To resolve this issue, you can patch your `/usr/bin/poff` file by making the following changes on line 93:

    -PID=`ps axw | grep "[ /]pppd call $1 *\$" | awk '{print $1}'`
    +PID=`ps axw | grep "[ /]pppd call $1" | awk '{print $1}'`

    /etc/rc.d/name-of-your-vpn

    #!/bin/bash

    . /etc/rc.conf
    . /etc/rc.d/functions

    DAEMON=<TUNNEL>-vpn
    ARGS=

    [ -r /etc/conf.d/$DAEMON ] && . /etc/conf.d/$DAEMON

    case "$1" in
     start)
       stat_busy "Starting $DAEMON"
       pon <TUNNEL> updetach persist &>/dev/null && <ROUTING COMMAND> &>/dev/null
       if [ $? = 0 ]; then
         add_daemon $DAEMON
         stat_done
       else
         stat_fail
         exit 1
       fi
       ;;
     stop)
       stat_busy "Stopping $DAEMON"
       poff <TUNNEL> &>/dev/null
       if [ $? = 0 ]; then
         rm_daemon $DAEMON
         stat_done
       else
         stat_fail
         exit 1
       fi
       ;;
     restart)
       $0 stop
       sleep 1
       $0 start
       ;;
     *)
       echo "usage: $0 {start|stop|restart}"
    esac

Note: We call `pon` in the script with two additional arguments: `updetach` and `persist`. The argument `updetach` makes pon block until the connection has been established. The other argument, `persist`, makes the network automatically reconnect in the event of a failure. To connect at boot add @<TUNNEL>-vpn to the end of your `DAEMONS` array in `/etc/rc.conf`.

## Troubleshooting

If client connections keep timing out, make sure that GRE is allowed through the client firewall. For iptables, the necessary command is:

    # iptables -A INPUT -p 47 -j ACCEPT

If your client is timing out with "LCP: timeout sending Config-Requests", then you might not have the proper modules loaded:

    # modprobe nf_conntrack_pptp nf_conntrack_proto_gre

## Remarks

You can find more information about configuring pptpclient at their website: pptpclient website. The contents of this article were adapted from their Ubuntu How-To which also provides some hints on how to do things such as connecting on boot. These examples should be easy to adapt into daemons or other scripts to help automate your configuration.

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