pptp failing

[w1z4rd]

For some reason pptp is failing and I am unable to make sense of the logs as to why its failing. Perhaps someone here knows log-fu better than I do?

Sep 7 15:58:48 mail pptpd[18171]: CTRL: Client 41.241.83.132 control connection started
Sep 7 15:58:48 mail pptpd[18171]: CTRL: Starting call (launching pppd, opening GRE)
Sep 7 15:58:48 mail pppd[18172]: pppd 2.4.3 started by root, uid 0
Sep 7 15:58:48 mail pppd[18172]: Changing interface to pptp0
Sep 7 15:58:48 mail pppd[18172]: Connect: pptp0 <--> /dev/pts/1
Sep 7 15:59:18 mail dnsmasq-dhcp[9907]: DHCPINFORM(eth1) 10.0.0.70 00:22:64:1d:9b:30
Sep 7 15:59:18 mail dnsmasq-dhcp[9907]: DHCPACK(eth1) 10.0.0.70 00:22:64:1d:9b:30 theath-PC
Sep 7 15:59:18 mail pppd[18172]: LCP: timeout sending Config-Requests
Sep 7 15:59:18 mail pppd[18172]: Connection terminated.
Sep 7 15:59:18 mail pppd[18172]: Changing interface to pptp0
Sep 7 15:59:18 mail pppd[18172]: Connect: pptp0 <--> /dev/pts/1
Sep 7 15:59:18 mail pppd[18172]: tcflush failed: Bad file descriptor
Sep 7 15:59:18 mail pppd[18172]: tcsetattr: Invalid argument (line 1001)
Sep 7 15:59:18 mail pppd[18172]: Exit.
Sep 7 15:59:18 mail pptpd[18171]: GRE: read(fd=6,buffer=8058f20,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs
Sep 7 15:59:18 mail pptpd[18171]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
Sep 7 15:59:18 mail pptpd[18171]: CTRL: Client 41.241.83.136 control connection finished

 

[The_Unbeliever]

A PPTP VPN server requires TCP port 1723 forwarded to the VPN server, as well as the GRE protocol (protocol 47).

There's the line

Sep 7 15:59:18 mail pptpd[18171]: GRE: read(fd=6,buffer=8058f20,len=8196) from PTY failed: status = -1

in the logs - do check if protocol 47 is enabled...

for more info - http://martybugs.net/smoothwall/vpn.cgi

 

[w1z4rd]

Im sure its enabled....

Here is a print out of my iptables:

[root@mail log]# iptables -L -n
Chain INPUT (policy DROP)
target prot opt source destination
DROP all -- 0.0.0.0/0 0.0.0.0/0 state INVALID
REJECT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp flags:0x12/0x12 state NEW reject-with tcp-reset
DROP tcp -- 0.0.0.0/0 0.0.0.0/0 tcp flags:!0x17/0x02 state NEW
DROP all -- 127.0.0.0/8 0.0.0.0/0
DROP all -- 169.254.0.0/16 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 0
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 3
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 8
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 11
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:67 dpt:68
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp spt:67 dpt:68
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:143
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:993
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:110
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:995
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:22
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:5222
ACCEPT udp -- 0.0.0.0/0 192.168.0.254 udp dpt:5222
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:1723
ACCEPT udp -- 0.0.0.0/0 192.168.0.254 udp dpt:1723
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:81
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:83
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:25
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:1875
ACCEPT 47 -- 0.0.0.0/0 192.168.0.254
ACCEPT tcp -- 0.0.0.0/0 192.168.0.254 tcp dpt:1723
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpts:1024:65535 state RELATED,ESTABLISHED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpts:1024:65535 state RELATED,ESTABLISHED

Chain FORWARD (policy DROP)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 10.0.0.7 tcp dpt:5222
ACCEPT udp -- 0.0.0.0/0 10.0.0.7 udp dpt:5222
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0

Chain OUTPUT (policy DROP)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:68 dpt:67
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp spt:68 dpt:67
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:143
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:993
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:110
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:995
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:22
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:5222
ACCEPT udp -- 192.168.0.254 0.0.0.0/0 udp spt:5222
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:1723
ACCEPT udp -- 192.168.0.254 0.0.0.0/0 udp spt:1723
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:81
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:83
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:25
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:1875
ACCEPT 47 -- 192.168.0.254 0.0.0.0/0
ACCEPT tcp -- 192.168.0.254 0.0.0.0/0 tcp spt:1723
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0

Chain drop-lan (0 references)
target prot opt source destination
DROP all -- 0.0.0.0/0 0.0.0.0/0

 

[s0lar]

Had a similar issue in the past where my MTU was "mysteriously" set to 1669? I setup a consistent MTU across the path and all was suddenly good.