ip_nat_pptp stretch not work

Discussion:

Alexey Kurinnij

2017-08-10 10:04:21 UTC

Hi. I have debian box with nat as gateway.
With debbian jessie pptp from local network worked, with loaded kernel
module ip_nat_pptp.
After upgrade to debian stretch - pptp not working any more, module
ip_nat_pptp loaded.
Anyone have similar working configuration?

# Generated by iptables-save v1.6.0 on Thu Aug 10 13:04:00 2017
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type any -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -i eth0 -p udp -m state --state NEW -m udp --dport 67 -j ACCEPT
-A INPUT -j DROP
-A FORWARD -s 192.168.1.0/24 ! -d 192.168.1.0/24 -i eth0 -j ACCEPT
-A FORWARD -d 192.168.1.0/24 -i eth1 -j ACCEPT
-A FORWARD -j DROP
-A OUTPUT -j ACCEPT
COMMIT
# Completed on Thu Aug 10 13:04:00 2017
# Generated by iptables-save v1.6.0 on Thu Aug 10 13:04:00 2017
*nat
:PREROUTING ACCEPT [8403:561775]
:INPUT ACCEPT [4:194]
:OUTPUT ACCEPT [295:18031]
:POSTROUTING ACCEPT [295:18031]
-A PREROUTING -i eth1 -p tcp -m tcp --dport 443 -j REDIRECT --to-ports 22
-A POSTROUTING -s 192.168.1.0/24 -o eth1 -j MASQUERADE
COMMIT
# Completed on Thu Aug 10 13:04:00 2017

Thierry JAOUEN

2017-08-10 11:59:04 UTC

Permalink

Hi,

Maybe you need the "helper" module ?

<https://home.regit.org/netfilter-en/secure-use-of-helpers/>
<http://www.spinics.net/lists/netfilter/msg11791.html>

... -m helper --helper pptp ...

Bye

Post by Alexey Kurinnij
Hi. I have debian box with nat as gateway.
With debbian jessie pptp from local network worked, with loaded kernel
module ip_nat_pptp.
After upgrade to debian stretch - pptp not working any more, module
ip_nat_pptp loaded.
Anyone have similar working configuration?
# Generated by iptables-save v1.6.0 on Thu Aug 10 13:04:00 2017
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type any -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -i eth0 -p udp -m state --state NEW -m udp --dport 67 -j ACCEPT
-A INPUT -j DROP
-A FORWARD -s 192.168.1.0/24 ! -d 192.168.1.0/24 -i eth0 -j ACCEPT
-A FORWARD -d 192.168.1.0/24 -i eth1 -j ACCEPT
-A FORWARD -j DROP
-A OUTPUT -j ACCEPT
COMMIT
# Completed on Thu Aug 10 13:04:00 2017
# Generated by iptables-save v1.6.0 on Thu Aug 10 13:04:00 2017
*nat
:PREROUTING ACCEPT [8403:561775]
:INPUT ACCEPT [4:194]
:OUTPUT ACCEPT [295:18031]
:POSTROUTING ACCEPT [295:18031]
-A PREROUTING -i eth1 -p tcp -m tcp --dport 443 -j REDIRECT --to-ports 22
-A POSTROUTING -s 192.168.1.0/24 -o eth1 -j MASQUERADE
COMMIT
# Completed on Thu Aug 10 13:04:00 2017

Alexey Kurinnij

2017-08-10 12:52:27 UTC

Permalink

Thanks for good point - nf_conntrack_helper was disabled by default and it
is difference between jessie and stretch
When I enable it - pptp from local network is working:

echo 1 > /proc/sys/net/netfilter/nf_conntrack_helper

Post by Thierry JAOUEN
Hi,
Maybe you need the "helper" module ?
<https://home.regit.org/netfilter-en/secure-use-of-helpers/>
<http://www.spinics.net/lists/netfilter/msg11791.html>
... -m helper --helper pptp ...
Bye