set up NAT (network address translation) on local server

[Antonio Olivares]

--- On Thu, 11/20/08, Christopher K. Johnson <ckjohnson at gwi.net> wrote:

> From: Christopher K. Johnson <ckjohnson at gwi.net>
> Subject: Re: set up NAT (network address translation) on local server
> To: "Community assistance, encouragement, and advice for using Fedora." <fedora-list at redhat.com>
> Date: Thursday, November 20, 2008, 10:27 AM
> It appears from your email that there was an editing error
> at the COMMIT or line after.
> Perhaps instead of a line-end on those lines it has spaces
> and wrapped them into one long line?
> Could happen from copy and paste depending on
> circumstances.
> Check that each rule is on its own line.
> 

I reset the iptables back to the original condition and added them, but still no joy :(


[root at localhost ~]# gedit /etc/sysconfig/iptables &            
[1] 8516                                                       
[root at localhost ~]# service iptables stop
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Setting chains to policy ACCEPT: filter          [  OK  ]
iptables: Unloading modules:                               [  OK  ]
[root at localhost ~]# service iptables restart
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Setting chains to policy ACCEPT: filter          [  OK  ]
iptables: Unloading modules:                               [  OK  ]
iptables: Applying firewall rules: Bad argument `iptables'         
Error occurred at line: 2                                          
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
                                                           [FAILED]         
[root at localhost ~]# service iptables stop
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Setting chains to policy ACCEPT: nat filter      [  OK  ]
iptables: Unloading modules:                               [  OK  ]
[root at localhost ~]# iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT [1]+  Done                    gedit /etc/sysconfig/iptables       
[root at localhost ~]# iptables -A FORWARD -i eth0 -o eth1 -m state --state ESTABLISHED,RELATED -j ACCEPT                                                          
[root at localhost ~]# iptables -A POSTROUTING -t nat -s 192.168.1.0/24 -o eth0 -j SNAT --to-source 10.154.19.210                                          
[root at localhost ~]# iptables-save
# Generated by iptables-save v1.4.1.1 on Thu Nov 20 13:14:50 2008
*nat                                                             
:PREROUTING ACCEPT [5:692]                                       
:POSTROUTING ACCEPT [0:0]                                        
:OUTPUT ACCEPT [0:0]                                             
-A POSTROUTING -s 192.168.1.0/24 -o eth0 -j SNAT --to-source 10.154.19.210 
COMMIT                                                                     
# Completed on Thu Nov 20 13:14:50 2008                                    
# Generated by iptables-save v1.4.1.1 on Thu Nov 20 13:14:50 2008          
*filter                                                                    
:INPUT ACCEPT [2483:1813687]                                               
:FORWARD ACCEPT [0:0]                                                      
:OUTPUT ACCEPT [2598:1049836]                                              
-A FORWARD -i eth1 -o eth0 -j ACCEPT                                       
-A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT  
COMMIT                                                                     
# Completed on Thu Nov 20 13:14:50 2008                                    
[root at localhost ~]# service iptables restart
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Setting chains to policy ACCEPT: nat filter      [  OK  ]
iptables: Unloading modules:                               [  OK  ]
iptables: Applying firewall rules:                         [  OK  ]
iptables: Loading additional modules: ip_conntrack_netbios_[  OK  ]
[root at localhost ~]# service dhcpd start                            
Starting dhcpd:                                            [  OK  ]
[root at localhost ~]#

The iptables get back to original state.  error in iptables-save ?/bug 

[root at localhost ~]# cat /etc/sysconfig/iptables
# Firewall configuration written by system-config-securitylevel
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -p 50 -j ACCEPT
-A RH-Firewall-1-INPUT -p 51 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp --dport 5353 -d 224.0.0.251 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT



Thanks,

Antonio