Openvpn nat and iptables


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Openvpn nat and iptables

good day good people

hi

first to tell that firewall and vpn is working as expected, but I notice something strange.

I have host system 11.11.11.11(local ip) firewall is blocking everything except port to vpn.
I have vpn on virtualized system 22.22.22.22 (CentOS both host and virtual). They are behind MikroTik router and then to my ISP router. This is a home setup I'm just experimenting.

PREROUTING 11.11.11.11:1194 to 22.22.22.22:1194 all other is blocked by iptables.
POSTROUTING 22.22.22.22 to 11.11.11.11

I noticed with Wireshark from host 11.11.11.11 that while I'm connected to vpn from another pc that 11.11.11.11 is connecting to ip addresses of websites I visit while in same time is connected to vpn. like:

11.11.11.11 XX.XX.XX public ip
11.11.11.11 tcp udp sites i visit

but 11.11.11.11 is unnecessarily making connections to website ip addresses. She cannot make the reqests because DNS and ports for that are blocked. So this is because postrouting command my best guess. Can this somehow be disabled? First this is a security issue, second its unnecessary.

Someone told me that this is because NAT setup. but I believe that this can be disabled somehow, I didn't find solution yet so maybe someone know how.

thanks


Moderator's Comments:
Mod Comment We had to correct a lot of spelling errors. Please put more effort into using proper english

Last edited by Scrutinizer; 11-05-2016 at 04:48 AM.. Reason: Spelling
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iptables-apply(8)					      System Manager's Manual						 iptables-apply(8)

NAME
iptables-apply - a safer way to update iptables remotely SYNOPSIS
iptables-apply [-hV] [-t timeout] ruleset-file DESCRIPTION
iptables-apply will try to apply a new ruleset (as output by iptables-save/read by iptables-restore) to iptables, then prompt the user whether the changes are okay. If the new ruleset cut the existing connection, the user will not be able to answer affirmatively. In this case, the script rolls back to the previous ruleset after the timeout expired. The timeout can be set with -t. When called as ip6tables-apply, the script will use ip6tables-save/-restore instead. OPTIONS
-t seconds, --timeout seconds Sets the timeout after which the script will roll back to the previous ruleset. -h, --help Display usage information. -V, --version Display version information. SEE ALSO
iptables-restore(8), iptables-save(8), iptables(8). LEGALESE
iptables-apply is copyright by Martin F. Krafft. This manual page was written by Martin F. Krafft <madduck@madduck.net> Permission is granted to copy, distribute and/or modify this document under the terms of the Artistic License 2.0. 2006-06-04 iptables-apply(8)

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