Remote IP for pptpd server

Question

I'm trying to set up a VPN server with pptpd, and I'm having trouble determining what range of IP addresses I should pass to it's remoteip configuration option. I can connect just fine to the VPN, but when I try to use the connection to make requests, it does not resolve.

Here's my pptpd.conf file:

###############################################################################
# $Id$
#
# Sample Poptop configuration file /etc/pptpd.conf
#
# Changes are effective when pptpd is restarted.
###############################################################################

# TAG: ppp
# Path to the pppd program, default '/usr/sbin/pppd' on Linux
#
#ppp /usr/sbin/pppd

# TAG: option
# Specifies the location of the PPP options file.
# By default PPP looks in '/etc/ppp/options'
#
option /etc/ppp/pptpd-options

# TAG: debug
# Turns on (more) debugging to syslog
#
debug

# TAG: stimeout
# Specifies timeout (in seconds) on starting ctrl connection
#
# stimeout 10

# TAG: noipparam
#       Suppress the passing of the client's IP address to PPP, which is
#       done by default otherwise.
#
#noipparam

# TAG: logwtmp
# Use wtmp(5) to record client connections and disconnections.
#
logwtmp

# TAG: bcrelay <if>
# Turns on broadcast relay to clients from interface <if>
#
#bcrelay eth1

# TAG: localip
# TAG: remoteip
# Specifies the local and remote IP address ranges.
#
#       Any addresses work as long as the local machine takes care of the
#       routing.  But if you want to use MS-Windows networking, you should
#       use IP addresses out of the LAN address space and use the proxyarp
#       option in the pppd options file, or run bcrelay.
#
# You can specify single IP addresses seperated by commas or you can
# specify ranges, or both. For example:
#
#   192.168.0.234,192.168.0.245-249,192.168.0.254
#
# IMPORTANT RESTRICTIONS:
#
# 1. No spaces are permitted between commas or within addresses.
#
# 2. If you give more IP addresses than MAX_CONNECTIONS, it will
#    start at the beginning of the list and go until it gets 
#    MAX_CONNECTIONS IPs. Others will be ignored.
#
# 3. No shortcuts in ranges! ie. 234-8 does not mean 234 to 238,
#    you must type 234-238 if you mean this.
#
# 4. If you give a single localIP, that's ok - all local IPs will
#    be set to the given one. You MUST still give at least one remote
#    IP for each simultaneous client.
#
# (Recommended)
localip 192.168.0.1
remoteip 192.168.0.170-180,192.168.0.245
# or
#localip 192.168.0.234-238,192.168.0.245
#remoteip 192.168.1.234-238,192.168.1.245


# Use Google's DNS
ms-dns 8.8.8.8
ms-dns 8.8.4.4

I tried to follow this tutorial.

When I connect to the VPN, and then try to ping, I get the following:

$ ping google.com
ping: cannot resolve google.com: Unknown host

Answer 1

First off, I suggest you drop PPTP as it is provably insecure and should not be relied upon for privacy, replace it with either OpenVPN or IPsec depending on the network environment/restrictions of the client systems.

Understanding this, if you wish to continue with PPTP:

Try ping 8.8.8.8 to rule out a dns issue.

If that doesn't work (and if you're forwarding all traffic through the VPN, which is a client option), you probably don't have IPv4 Forwarding enabled in your pptp server's linux(I'm assuming here) kernel.

To do so immediately:

# sysctl -w net.ipv4.ip_forward=1

Then to make that configuration permanent edit /etc/sysctl.conf and find the section referencing net.ipv4.ip_forward and un-comment(remove # at start of line) it.

If you have any firewall rules check that they allow for masqueraded/NAT traffic.

Answer 2

The pptpd package for Ubuntu only support i386 architecture – I was using a x86 version of Ubuntu.