Sponsored Content
Full Discussion: NAT Loopback and iptables
Operating Systems Linux Red Hat NAT Loopback and iptables Post 302790931 by 6765656755 on Sunday 7th of April 2013 11:18:42 AM
Old 04-07-2013
RedHat 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 open that from the local network (Clients).
As I know i have to add NAT Loopback rules in iptables but I even have no ideas which one rules.
Please, help me ...
If it is important, i use MASQUERADE, bc my external IP is dynamic.
Now my iptables looks like that:
Code:
[root@hprouter ~]# service iptables status
Table: filter
Chain INPUT (policy ACCEPT)
num  target     prot opt source               destination         
1    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED 
2    ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0           
3    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           
4    ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:22 
5    ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:53 
6    ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0           state NEW udp dpt:53 
7    REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited 

Chain FORWARD (policy ACCEPT)
num  target     prot opt source               destination         
1    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED 
2    ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0           
3    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           
4    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           
5    ACCEPT     tcp  --  0.0.0.0/0            10.0.1.15           state NEW tcp dpt:80 
6    REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited 

Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination         

Table: nat
Chain PREROUTING (policy ACCEPT)
num  target     prot opt source               destination         
1    DNAT       tcp  --  0.0.0.0/0            0.0.0.0/0           tcp dpt:80 to:10.0.1.15:80 

Chain POSTROUTING (policy ACCEPT)
num  target     prot opt source               destination         
1    MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0           

Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination

NAT Loopback and iptables-10010_24png
 

10 More Discussions You Might Find Interesting

1. 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

2. Red Hat

Can't ping on Fedora 10 affer config NAT iptables

Currently,i use Fedora 10 and get a follow trouble : My network: route(10.11.10.2/24)----eth0----(10.11.10.105/24)Fedora10(172.16.239.1/24)----vmnet0----(172.16.239.2/24)Virtual Machine XP2. I used : Vmware 6.5.1,Virtual Machine : Window XP SP2. , iptable 1.4.1.1 I set up static ip... (2 Replies)
Discussion started by: kideltn
2 Replies

3. IP Networking

How to configure Full Cone NAT using iptables ?

Hi Experts; I want to find the right iptables commands combination to address the following need: - NEs are NATed thru the linux box (using iptables) towards the WAN cloud, where the NTP servers are situated. - In order to achieve redundancy, the NTP Servers are in a load balancing cluster... (0 Replies)
Discussion started by: lvl1s7a
0 Replies

4. 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

5. 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

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. IP Networking

Debugging NAT / prerouting issues (iptables)

Hello, Recently I discovered an issue with packet routing in the latest Android releases (4.4+ KitKat & Lollipop). It seems that the problem Android specific, but essentially it comes from the Linux kernel. I already filed a bug report to Google. You can see the details by searching for... (0 Replies)
Discussion started by: Vladislav
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. Cybersecurity

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). ... (0 Replies)
Discussion started by: end
0 Replies
LOCKOUT(1)							      lockout								LOCKOUT(1)

NAME
lockout - avoid slacking and impose productivity and discipline on yourself WARNING
This program is VERY DANGEROUS. If it fails, you may end up not knowing the root password to your own computer (in which case you need to boot into single-user mode). There are no known reports of this actually happening, but we don't know how stupid you are. Also, you should probably not run this on a multi-user system. SYNOPSIS
lockout lock HhMm | Hh | Mm lockout lock HH:MM lockout lock HH:MMam | HH:MMpm lockout lock HHam | HHpm lockout lock lockout unlock [force] lockout status DESCRIPTION
Lockout is a tool that imposes discipline on you so that you get some work done. For example, lockout can be used to install a firewall that does not let you browse the Web. Lockout changes the root password for a specified duration; this prevents you from secretly ripping down the firewall and then browsing the Web anyway. In case of an emergency, you can reboot your computer to undo the effects of lockout and to restore the original root password. Obviously, lockout lock and lockout unlock can only be run by root. lockout status can be run by any user. lockout without any parameters shows a brief help message. lockout lock takes one optional parameter. If no parameter is given, you are dropped in interactive mode and asked for the duration of the lock or the time at which the lock should be lifted. You can also supply this as a parameter on the command line. Lockout understands various time formats. You can specify a delay, e.g., 3h (3 hours), 1h30m (1 hour and 30 minutes), or 90m (1 hour and 30 minutes), or you can specify absolute time, e.g., 2pm, 2:30am, 15:30, etc. You will be asked to confirm the time at which lockout will unlock your system. If you type "yes", lockout executes /etc/lockout/lock.sh and changes the root password to something completely random. /etc/lock- out/lock.sh is a shell script that you write. It takes measures to make sure you stop slacking. For example, it could install a firewall that prevents outgoing connections to port 80. See the "EXAMPLES" section below. lockout unlock takes an optional force parameter. Without any parameters, lockout lock will check whether it is time to unlock the system and, if so, executes /etc/lockout/unlock.sh, which is a shell script that you write. It should undo the effects of /etc/lockout/lock.sh, executed when the system was locked. If you pass the force parameter to lockout unlock, lockout will forcibly unlock your system, whether it was really time for that or not. lockout unlock should be called every minute by cron. See "CONFIGURATION". lockout status will print out the time at which the system is going to be unlocked. CONFIGURATION
/etc/cron.d/lockout must contain the following two entries: */1 * * * * root /usr/bin/lockout unlock >/dev/null 2>&1 @reboot root /usr/bin/lockout unlock force >/dev/null 2>&1 The examples that follow assume you are using sudo(8) and you have a file, /etc/lockout/sudoers.normal which is the normal /etc/sudoers file, and /etc/lockout/sudoers.lock, which is the /etc/sudoers file when lockout locks your computer. This example also assumes you are using iptables(8). /var/lib/iptables/active should contain your default firewall rules, and /var/lib/iptables/work should contain the firewall rules that enforce discipline. See below for an example. /etc/lock/lock.sh imposes discipline. For example: #!/bin/sh /etc/init.d/iptables load work cp /etc/lockout/sudoers.lock /etc/sudoers /etc/init.d/sudo stop /etc/init.d/sudo start /etc/lock/unlock.sh undoes these effects. For example: #!/bin/sh /etc/init.d/iptables restart cp /etc/lockout/sudoers.normal /etc/sudoers /etc/init.d/sudo stop /etc/init.d/sudo start Your /var/lib/iptables/work may look something like this: *filter :INPUT ACCEPT [1047:99548] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [1104:120792] # allow incoming packets from localhost, ntp, # and existing connections -A INPUT -i lo -j ACCEPT -A INPUT -p udp -m udp --source-port ntp -m state --state ESTABLISHED -j ACCEPT -A INPUT -m state --state ESTABLISHED -j ACCEPT -A INPUT -p tcp -j DROP -A INPUT -p udp -j DROP # allow outgoing connections for email and DNS -A OUTPUT -d 127.0.0.1/8 -j ACCEPT -A OUTPUT -p tcp -m tcp --dport smtp -j ACCEPT -A OUTPUT -p tcp -m tcp --dport domain -j ACCEPT -A OUTPUT -p udp -m udp --dport domain -j ACCEPT -A OUTPUT -j DROP COMMIT EXAMPLES
lockout lock 2h30m [locks out for 2h and 30m] lockout lock 90m [locks out for 1h and 30m] lockout lock 3pm [locks out until 3pm] lockout lock 3:20am [locks out until 3:20am] lockout lock 15:20 [locks out until 3:20pm] lockout status [shows when the system is going to be unlocked] FILES
/etc/lockout/lock.sh: executed when running lockout lock /etc/lockout/unlock.sh: executed when running lockout unlock SEE ALSO
usermod(8), iptables(8), passwd(1), cron(8), crontab(1) BUGS
Arguably, a program that changes the root password to something random with the possibility of never recovering the original password might be considered a bug by itself. Other than that, no known bugs. AUTHOR
Thomer M. Gil, http://thomer.com/lockout/ lockout 2004-09-08 LOCKOUT(1)
All times are GMT -4. The time now is 09:59 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy