Internet Access Through pptp vpn server on centos

Internet Access Through pptp vpn server on centos

Installation and Configuration of PPTP
Add the Poptop Yum Repository
rpm -Uhv http://poptop.sourceforge.net/yum/stable/rhel5/pptp-release-current.noarch.rpm
yum install ppp pptpd
Configure Kernel
Edit /etc/sysctl.conf
FROM net.ipv4.ip_forward = 0 To net.ipv4.ip_forward = 1
Verify changes sysctl –p
Configure Client Network Options
Modify /etc/pptpd.conf
localip 192.168.50.1
remoteip 192.168.50.2-15
Modify /etc/ppp/options.pptpd
ms-dns 8.8.8.8
ms-dns 8.8.4.4
Configure Client Access
Edit /etc/ppp/chap-secrets.
# Secrets for authentication using CHAP
# client        server  secret                  IP addresses
mccarrms        *       mccarrms-password       *
IPTables Rules
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -p gre -j ACCEPT
-A INPUT -p gre -j ACCEPT
-A INPUT -p gre -j ACCEPT
-A FORWARD -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp -m icmp --icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -p esp -j ACCEPT
-A RH-Firewall-1-INPUT -p ah -j ACCEPT
-A RH-Firewall-1-INPUT -d 224.0.0.251 -p udp -m udp --dport 5353 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 21 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 25 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 2049 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m state --state NEW -m udp --dport 137 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m state --state NEW -m udp --dport 53 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m state --state NEW -m udp --dport 138 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 139 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 445 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 443 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 23 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 1723 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 47 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 8245 -j ACCEPT
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT
*nat
:PREROUTING ACCEPT [1788:95928]
:POSTROUTING ACCEPT [90:5683]
:OUTPUT ACCEPT [90:5683]
-A POSTROUTING -s 192.168.50.0/255.255.255.0 -o eth0 -j MASQUERADE
-A POSTROUTING -o ppp0 -j MASQUERADE
COMMIT

Reference link
http://docs.cslabs.clarkson.edu/wiki/Install_PPTP_on_CentOS_5
https://www.centos.org/modules/newbb/viewtopic.php?topic_id=38783
http://blog.colovirt.com/2009/06/02/linux-security-iptables-cli-list-rules-without-dns-resolution/
http://serverfault.com/questions/407656/connect-linux-server-to-vpn-server-via-pptp
http://www.thegeekstuff.com/2011/06/iptables-rules-examples/