最後更新: 2015-06-29

Centos 6 上安裝

1. rpm --import http://poptop.sourceforge.net/yum/RPM-GPG-KEY-PPTP
2. rpm -Uvh http://poptop.sourceforge.net/yum/stable/rhel6/pptp-release-current.noar...
3. yum install ppp pptpd -y

設定:

# 設定 IP

/etc/pptpd.conf

option /etc/ppp/options.pptpd

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

# Turns on broadcast relay to clients from interface <if>
#bcrelay eth0

# Delegates the allocation of client IP addresses to pppd
# 用左佢 localip 及 remoteip 會無效
#delegate

# Limits the number of client connections
connections 100

localip 192.168.1.1
remoteip 192.168.1.234-238,192.168.1.245

# 為 Client 設定 DNS

echo "ms-dns 192.168.1.1" >> /etc/ppp/options.pptpd

一行一個 DNS Server

ms-dns 192.168.1.1
ms-dns 8.8.8.8

* 沒有這 setting, window client 會無左 DNS Server

# 加 User

echo "$USERNAME pptpd $PASSWORD *" >> /etc/ppp/chap-secrets

chap-secrets format

# Dialin format: <remote name> <our name> <password> <allowed IP addresses>
joe    server    password    192.168.0.221

啟動:

chkconfig pptpd on

service pptpd restart

透過 PPTP 出 WAN (NAT)

/etc/sysctl.conf

net.ipv4.ip_forward = 1

修改 /etc/sysconfig/iptables, 加入

iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

service iptables save

service iptables restart

Firewall 設定

-A INPUT -m tcp -p tcp --dport 1723 -j ACCEPT
-A INPUT -m tcp -p tcp -i ppp+ -j ACCEPT
-A FORWARD -i ppp+ -j ACCEPT
-A FORWARD -o ppp+ -j ACCEPT

Troubleshoot

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log

Jun 29 11:35:27 vpn01 pptpd[27498]: CTRL: Client x.x.x.x control connection started
Jun 29 11:35:27 vpn01 pptpd[27498]: CTRL: Starting call (launching pppd, opening GRE)
Jun 29 11:35:27 vpn01 pppd[27499]: Plugin /usr/lib/pptpd/pptpd-logwtmp.so loaded.
Jun 29 11:35:27 vpn01 pppd[27499]: pppd 2.4.5 started by root, uid 0
Jun 29 11:35:27 vpn01 pppd[27499]: Using interface ppp0
Jun 29 11:35:27 vpn01 pppd[27499]: Connect: ppp0 <--> /dev/pts/0
... wait ...
Jun 29 11:35:57 vpn01 pppd[27499]: LCP: timeout sending Config-Requests
Jun 29 11:35:57 vpn01 pppd[27499]: Connection terminated.
Jun 29 11:35:57 vpn01 pppd[27499]: Modem hangup
Jun 29 11:35:57 vpn01 pppd[27499]: Exit.
Jun 29 11:35:57 vpn01 pptpd[27498]: GRE: read(fd=6,buffer=805a480,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs
Jun 29 11:35:57 vpn01 pptpd[27498]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
Jun 29 11:35:57 vpn01 pptpd[27498]: CTRL: Client x.x.x.x control connection finished

WLAN box was most likely not handling GRE (protocol 47) correctly

* GRE/PPTP box under Tracking/NAT helpers

- nf_conntrack_pptp
- nf_conntrack_proto_gre

DOC

http://pptpclient.sourceforge.net/howto-diagnosis.phtml#lcp_timeout

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