I have a PPTP server inside (green) a network. The old firewall was ipchains-based, and now it's iptables. I can't seem to figure out how to route GRE (protocol 47) and 1723 so that it works.

Jan 17, 2010 · Just a handy little reference for myself. #Internal PPTP Server. vpnserver=”172.16.1.10″. iptables -N pptp. iptables -A pptp -p tcp –destination-port 1723 –dst $vpnserver -j ACCEPT. iptables -A pptp -p gre –dst $vpnserver -j ACCEPT. iptables -I FORWARD -j pptp. May 14, 2013 · A PPTP VPN server requires TCP port 1723 forwarded to the VPN server, as well as the GRE protocol (protocol 47). As the Smoothwall web interface doesn't provide functionality for forwarding the GRE protocol, you'll have to edit the firewall script. Editing the Firewall Script: Nov 28, 2011 · 1723, 47, 50, and 500 do i need to open these ports for VPN to work? Thanks in advance. Wednesday, November 23, 2011 10:28 AM. SSTP: port 443 TCP ; PPTP: 1723 It is also for PPTP VPN connections. Simple Mail Transfer Protocol operates on tcp port 25. iptables -I FORWARD 1 -p tcp -s 192.168.1.2 --dport 25 -j ACCEPT Jan 06, 2009 · PPTP Vpn through a Linux IpTables/Netfilter firewall I spent some time configuring a pptp vpn for one of our offices yesterday, but it kept failing to connect during testing. Each failure generated these errors in the firewall (the one I was Vpn-ing too) log.

# Accept all packets via ppp* interfaces (for example, ppp0) iptables -A INPUT -i ppp+ -j ACCEPT iptables -A OUTPUT -o ppp+ -j ACCEPT # Accept incoming connections to port 1723 (PPTP) iptables -A INPUT -p tcp --dport 1723 -j ACCEPT # Accept GRE packets iptables -A INPUT -p 47 -j ACCEPT iptables -A OUTPUT -p 47 -j ACCEPT # Enable IP forwarding iptables -F FORWARD iptables -A FORWARD -j ACCEPT # Enable NAT for eth0 on ppp* interfaces iptables -A POSTROUTING -t nat -o eth0 -j MASQUERADE

Apr 04, 2018 · Point-to-point tunneling protocol is a common protocol because it’s been implemented in Windows in various forms since Windows 95. PPTP has many known security issues, and it’s likely the NSA (and probably other intelligence agencies) are decrypting these supposedly “secure” connections. 2. Disable DHCP server on the DD-WRT, only if you want certain devices to access the internet via the VPN (This option you will need to set the static gateway IP on your device to that of the DD-WRT router) Click the ‘Services’ tab in the menu and select ‘VPN’ from the submenu bar. Click ‘Enable’ to ‘PPTP Client Options’ Posted June 22, 2016 By BrookDO. In order to block port 80, you would add this to your iptables shell script: # /sbin/iptables -A INPUT -p tcp --destination-port 80 -j DROP # /sbin/service iptables save Jul 09, 2020 · PPTP has been superseded by safer and more secure VPN tunneling protocols, including OpenVPN, L2TP/IPSec, and IKEv2/IPSec. How PPTP Works PPTP is an outgrowth of PPP, and as such, is based on its authentication and encryption framework.

Hi, I seem to be having some issues with Centos 4.4 (2.6.9-22.EL) & iptables. I have a VPN server behind my firewall (running centos 4.4) which I want to allow PPTP & GRE to.

Figure 19.6. Traffic does not route through PPTP VPN. As PPTP also uses GRE protocol 47, it is also necessary to build your kernel with GRE support, documented here, and if that support is modular, the ip_gre module is loaded in the kernel: modprobe ip_gre . Note. Versions of pptpclient 1.2.0 and greater no longer require this. May 16, 2013 · The following iptables firewall rules allow port 1723, GRE and perform NAT. iptables -I INPUT -p tcp --dport 1723 -m state --state NEW -j ACCEPT iptables -I INPUT -p gre -j ACCEPT iptables -t nat -I POSTROUTING -o eth0 -j MASQUERADE. In the last rule replace “eth0” with the interface connecting to the internet on your VPN server. Jul 11, 2018 · This ruleset replaces the pre-exiting iptables rules and instructs the firewall to drop every outgoing connection other than loopback traffic, the local network’s subnet and UDP traffic to and from your OpenVPN server’s IP on port 1194. Apr 24, 2019 · PPTP VPN: From the Port Forwarding screen, set Local Port to 1723 and Protocol to TCP for PPTP tunnel, and then set Port Range to 47 and Protocol to Other for GRE tunnel. OpenVPN: From the Port Forwarding screen, set Local Port to 1194 and Protocol to UDP for OpenVPN tunnel. Internet -> WAN IP:Port -> Forward to Client VPN IP:Port. So for instance, if I had port 6000 open on my client, a person could telnet in to x.x.x.x:6000, and the server would catch that and forward it to 192.168.3.100:6000. I have tried at least 20 different Googled up iptables configs and none have worked yet. Does anyone have any ideas, or Jan 17, 2010 · Just a handy little reference for myself. #Internal PPTP Server. vpnserver=”172.16.1.10″. iptables -N pptp. iptables -A pptp -p tcp –destination-port 1723 –dst $vpnserver -j ACCEPT. iptables -A pptp -p gre –dst $vpnserver -j ACCEPT. iptables -I FORWARD -j pptp.