CentOS/Ubuntu VPN proxy server configuration tutorial

Configure the VPN proxy server in CentOS

I use CentOS 6.4 Here. The configurations of other linux versions are basically the same.

1. Check whether the PPP and TUN devices of the VPS are correctly installed.

 

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Ls/dev/ppp Ls/dev/net/tun # Or Cat/dev/ppp Cat/dev/net/tun

If the message "No such file or directory" or "No such device or address" is displayed, it indicates that it is not installed. Generally, you can open a ticket directly to your VPS provider.

2. Install pptp. Since pptp depends on ppp, you need to install ppp first.

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Yum install-y ppp Yum install-y pptp

3. Create a VPN pipe

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Mknod/dev/ppp c 108 0

If the 619 error occurs during VPN connection, you can also execute the above

4. Modify/etc/sysctl. conf to enable ipv4 forwarding.
Open the file, find the following content, and modify it.

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Net. ipv4.ip _ forward = 1 Net. ipv4.tcp _ syncookies = 0

Modification to/etc/sysctl. conf (optional)

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Sysctl-p

Or execute

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Echo 1>/proc/sys/net/ipv4/ip_forward Echo 0>/proc/sys/net/ipv4/tcp_syncookies

5. Modify the/etc/pptpd. conf file and set the vpn ip address. Write

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Localip XXX. XXX Remoteip XXX.XXX.XXX.XXX-XXX

Localip is the local IP address, that is, the local IP address.
The remoteip is the IP address allocated to the remote host. It is usually set to a continuous ip segment.

6. Modify the/etc/ppp/options.ppt pd file to complete DNS modification for the VPS server.

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Ms-dns 8.8.8.8 Ms-dns 8.8.4.4

7. Edit/etc/ppp/chap-secrets and configure the VPN connection user.
Format:

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Username pptpd password * Username: User name Password: password Or execute Echo "username pptpd password *">/etc/ppp/chap-secrets

8. Modify iptables settings and enable firewall

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Iptables-a forward-s XXX. XXX/XX-p tcp-m tcp -- tcp-flags FIN, SYN, RST, ack syn-j TCPMSS -- set-mss 1356   # Save Service iptables save

XXX. XXX/XX is the remote IP address set in step 1.

9. Configure the startup service (optional)

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Chkconfig iptables on Chkconfig pptpd on

10. Start or restart the pptp and iptables services.

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# Service iptables start # Service pptpd start   Service iptables restart Service pptpd restart

Configure the VPN proxy server in Ubuntu

The operating system is Ubuntu Server12.04.3. All operations are performed after sudo su.

1. Check whether the PPP device or TUN device is installed (skip DigitalOcean VPS)

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Ls/dev/ppp Ls/dev/net/tun # Or Cat/dev/ppp Cat/dev/net/tun

If the system prompts "No such file or directory" or "No such device or address", it indicates that the system is not installed. Open a ticket

2. Install pptpd

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Apt-get install pptpd

3. After the installation is successful, modify the/etc/pptd. conf file and configure the vpn ip address to write data.

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Localip XXX. XXX Remoteip XXX.XXX.XXX.XXX-XXX # Reference configuration # Localip 10.0.0.1 # Remoteip 10.0.0.100-200

Localip is the local IP address, that is, the local IP address.
The remoteip is the IP address allocated to the remote host. It is usually set to a continuous ip segment.

4. Modify the/etc/ppp/options.ppt pd file to complete DNS modification for the VPS server.

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Ms-dns 8.8.8.8 Ms-dns 8.8.4.4

5. Edit/etc/ppp/chap-secrets and configure the VPN connection user.
Format:

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Username pptpd password * Username indicates the user name Pptpd indicates the service name, which is generally the default value. Password indicates the password. * Asterisk indicates that all IP addresses can be connected.

6. Enable IP forwarding, modify/etc/sysctl. conf, and enable ipv4 forwarding.
Open the file, find the following content, and modify it. No. Please add.
# Enable IP forwarding

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Net. ipv4.ip _ forward = 1

 
# Enable SYN cookies to prevent SYN flood attacks. We recommend that you enable these cookies when connecting multiple users.
Net. ipv4.tcp _ syncookies = 0

Modification to/etc/sysctl. conf (optional)

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Sysctl-p

7. Open the firewall

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Iptables-t nat-a postrouting-o eth0-j MASQUERADE & iptables-save

8. Start pptp vpn service

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Service pptpd start