Sponsored Content
Full Discussion: Openvpn nat and iptables
Special Forums Cybersecurity Openvpn nat and iptables Post 302985097 by end on Friday 4th of November 2016 07:21:18 PM
Old 11-04-2016
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
 

10 More Discussions You Might Find Interesting

1. IP Networking

Iptables/TC: how to make masqueraded traffic go through an openVPN tun0?

Hi all! We have a setup of three computers; Machine A (eth0) -> Machine B (eth0, hso0, tun0) -> Machine C (eth0, tun0) hso0 is the packet interface of a 3G modem, it behaves like a normal network interface. Machine B and C are connected in a VPN using openVPN (TCP). Machine A is a... (2 Replies)
Discussion started by: theVOID
2 Replies

2. UNIX for Advanced & Expert Users

iptables internal NAT with two public IP

Hello Guys, I have a debian machine that work as a firewall (iptables + squid 2.6) with two physical interfaces: eth0 (public interface) and eth1 (internal interface LAN). I have created an alias eth1:1 in order to have two subnets on same physical interface: cat/etc/network/interfaces auto... (0 Replies)
Discussion started by: sincity2006
0 Replies

3. Debian

Iptables Nat forward port 29070

Hello, the Nat and the forward worked on my debian server up to the reboot of machines. The following rules*: /sbin/iptables -t nat -A PREROUTING -p tcp -i eth2 -d xxx.xxx.xxx.xxx --dport 29070 -j DNAT --to-destination 10.0.1.7:29070 /sbin/iptables -A FORWARD -p tcp -i eth2 -o eth0 -d... (0 Replies)
Discussion started by: titoms
0 Replies

4. IP Networking

iptables NAT prerouting & postrouting

Good morning, I'm a newbie of iptables and as far as I've seen on tutorials on the Internet it seems that both prerouting and postrouting NAT chains are undergone both by a packet that goes from an internal LAN to the Internet and of a one that goes in the opposite direction (from the Internet to... (0 Replies)
Discussion started by: giac85
0 Replies

5. Red Hat

NAT Loopback and iptables

Hello, please can you help and explain me. I have two servers. Both are RHEL6. I use the first one like router and the second one for apache. Router forwards 80 port on the second server and I can open that from the internet (mysite.com, for example). But I can not open mysite.com if i try to... (0 Replies)
Discussion started by: 6765656755
0 Replies

6. Cybersecurity

iptables in a NAT scenario

Hi, I am learning IPTables have this question. My server is behind a firewall that does a PAT & NAT to the LAN address. Internet IP: 68.1.1.23 Port: 10022 Server LAN IP: 10.1.1.23 port: 22 Allowed Internet IPs: 131.1.1.23, 132.1.1.23 I want to allow a set of IPs are to be able to... (1 Reply)
Discussion started by: capri_guy84
1 Replies

7. IP Networking

Nat and packet limits with iptables

Hi all, I have a following situation: - I want certain source IPs to be natted to a different destination IP and Port. Following is how I am achieving it: /usr/local/sbin/iptables -t nat -A PREROUTING -p tcp -s 192.168.10.12 --dport 1500 -j DNAT --to-destination 192.168.10.20:2000 ... (3 Replies)
Discussion started by: ahmerin
3 Replies

8. UNIX for Dummies Questions & Answers

iptables for openvpn

Hey all, I'm trying to get openvpn working on DD-WRT router. I can make a connection inside my lan, but outside the connection is yellow. I think yellow means it is close to making a connection, but it never completes the connection. So I believe there is a problem with my iptables since it... (0 Replies)
Discussion started by: sdnix
0 Replies

9. IP Networking

NAT via iptables - Won't work!!

Hi guys I'm running on debian on a small embedded system. I have a ppp interface that is connected to the internet (and works). My unit also has wifi access point (which works and I can connect to it). I want to allow connections to the wifi to be able to use the internet from ppp0... (1 Reply)
Discussion started by: alirezan1
1 Replies

10. Solaris

OpenVPN and NAT

Hi. I am attempting to set up an OpenVPN server on my Solaris 11 box by following all the Linux guides. Thus far I have a working VPN that I can connect to and ssh onto my VPN server over which is great but not what I require long term. I would like to route all VPN client requests for addresses... (0 Replies)
Discussion started by: nickb1976
0 Replies
RACOONCTL(8)                                                BSD System Manager's Manual                                               RACOONCTL(8)

NAME
racoonctl -- racoon administrative control tool SYNOPSIS
racoonctl [opts] reload-config racoonctl [opts] show-schedule racoonctl [opts] show-sa [isakmp|esp|ah|ipsec] racoonctl [opts] get-sa-cert [inet|inet6] src dst racoonctl [opts] flush-sa [isakmp|esp|ah|ipsec] racoonctl [opts] delete-sa saopts racoonctl [opts] establish-sa [-w] [-n remoteconf] [-u identity] saopts racoonctl [opts] vpn-connect [-u identity] vpn_gateway racoonctl [opts] vpn-disconnect vpn_gateway racoonctl [opts] show-event racoonctl [opts] logout-user login DESCRIPTION
racoonctl is used to control racoon(8) operation, if ipsec-tools was configured with adminport support. Communication between racoonctl and racoon(8) is done through a UNIX socket. By changing the default mode and ownership of the socket, you can allow non-root users to alter racoon(8) behavior, so do that with caution. The following general options are available: -d Debug mode. Hexdump sent admin port commands. -l Increase verbosity. Mainly for show-sa command. -s socket Specify unix socket name used to connecting racoon. The following commands are available: reload-config This should cause racoon(8) to reload its configuration file. show-schedule Unknown command. show-sa [isakmp|esp|ah|ipsec] Dump the SA: All the SAs if no SA class is provided, or either ISAKMP SAs, IPsec ESP SAs, IPsec AH SAs, or all IPsec SAs. Use -l to increase verbosity. get-sa-cert [inet|inet6] src dst Output the raw certificate that was used to authenticate the phase 1 matching src and dst. flush-sa [isakmp|esp|ah|ipsec] is used to flush all SAs if no SA class is provided, or a class of SAs, either ISAKMP SAs, IPsec ESP SAs, IPsec AH SAs, or all IPsec SAs. establish-sa [-w] [-n remoteconf] [-u username] saopts Establish an SA, either an ISAKMP SA, IPsec ESP SA, or IPsec AH SA. The optional -u username can be used when establishing an ISAKMP SA while hybrid auth is in use. The exact remote block to use can be specified with -n remoteconf. racoonctl will prompt you for the password associated with username and these credentials will be used in the Xauth exchange. Specifying -w will make racoonctl wait until the SA is actually established or an error occurs. saopts has the following format: isakmp {inet|inet6} src dst {esp|ah} {inet|inet6} src/prefixlen/port dst/prefixlen/port {icmp|tcp|udp|gre|any} vpn-connect [-u username] vpn_gateway This is a particular case of the previous command. It will establish an ISAKMP SA with vpn_gateway. delete-sa saopts Delete an SA, either an ISAKMP SA, IPsec ESP SA, or IPsec AH SA. vpn-disconnect vpn_gateway This is a particular case of the previous command. It will kill all SAs associated with vpn_gateway. show-event Listen for all events reported by racoon(8). logout-user login Delete all SA established on behalf of the Xauth user login. Command shortcuts are available: rc reload-config ss show-sa sc show-schedule fs flush-sa ds delete-sa es establish-sa vc vpn-connect vd vpn-disconnect se show-event lu logout-user RETURN VALUES
The command should exit with 0 on success, and non-zero on errors. FILES
/var/racoon/racoon.sock or /var/run/racoon.sock racoon(8) control socket. SEE ALSO
ipsec(4), racoon(8) HISTORY
Once was kmpstat in the KAME project. It turned into racoonctl but remained undocumented for a while. Emmanuel Dreyfus <manu@NetBSD.org> wrote this man page. BSD March 12, 2009 BSD
All times are GMT -4. The time now is 07:26 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy