Networking :: Firewall Installed Using IPtables - NAT Rules?
Apr 7, 2010
I just install 1 firewall using Iptables.
Firewall includes 2 NIC:
NIC1 <IP PUBLIC>
NIC2 192.168.10.1
I installed 1 web server IP: 192.168.10.2
I have some PC IP range: 192.168.10.10->20
I set rules NAT on firewall and PC & web server can connect internet good, but I have problems:
When PC access to web server with IP 192.168.10.2 that ok, but PC can't access to web server when using IP Public. But outside internet, I can access to web server using IP Public.
Rules on IPTables
Code:
# Generated by iptables-save v1.3.5 on Sun Mar 7 21:01:16 2010
*nat
:PREROUTING ACCEPT [950:126970]
:POSTROUTING ACCEPT [89:5880]
:OUTPUT ACCEPT [19:1342]
-A PREROUTING -d 209.99.242.124 -i eth0 -p tcp -m tcp --dport 80 -j DNAT --to-destination 192.168.10.2:80
-A POSTROUTING -s 192.168.10.0/24 -o eth0 -j SNAT --to-source 209.99.242.124
*filter
:INPUT DROP [1599:157409]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [232:34452]
-A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i eth1 -o eth0 -j ACCEPT
-A FORWARD -i eth0 -o eth1 -d 192.168.10.2 -p tcp --dport 80 -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -i eth1 -j ACCEPT
-A OUTPUT -o lo -j ACCEPT
-A OUTPUT -o eth1 -j ACCEPT
COMMIT
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Jul 17, 2010
IPtables creates an error during startup as well as when I try to restart it: Here's the output of:
[Code]....
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Jan 8, 2010
I am booting centos 5.4 on machine. The system hangs at line "Applying iptables firewall rules".Is there any way to skip starting iptables service during boot or disable it during boot so the system finally reboots.
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Nov 29, 2010
Even though I've set up HTTPS to be trusted, it still blocks my school's https site: "mnsu.edu/eservices" same with SAMBA and SSH.
If enter the GUI and authenticate as root, change anything and apply, then exit: it works fine and so does SAMBA. However, after restarting, everything stops working again.
yet secure firewall configuration that doesn't require any login or headaches.
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May 22, 2011
I added a few rules to my /etc/iptables.rules file and then used sudo iptables-restore < /etc/iptables.rules but i got an error saying "iptables-restore: line 29 failed".But the only word on that line.
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Jun 7, 2011
every now and then Firewall Builder fails to open rules (*.fwb)and I have to use some old backup. it does load 'object libraries' but the main 'currently editing policy' panel is empty.(in gnome, debian testing amd64)
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Mar 10, 2011
I need with some iptables rules. I've done all I can, Googling all over, to cover as many exploits as possible and the following script is what I've come up with. The current set up works and I've checked with NMAP. I just need some sort of confirmation that this is pretty much what I can do.
Code:
LAN="eth0 eth1"
RANGE=10.1.0.0/17
WAN=eth2
# Delete all existing rules
[code]....
Also, if I wanted a broadcast to be relayed to all subnets within a defined range, how would such a iptables rule look like? I need this in order to find a networked Canon MP640 printer.
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Jan 25, 2010
I am trying solve a strange problem which ocurred after upgrading many packages including kernel and iptables.This is a Fedora 10 PC acting as a small home-server I've been using over a year without problems. Recently, I've run a yum upgrade and after that, connections outside home wouldn't work. No changes in IPtables (firewall) rules have been done. But connection through local network is working.Symptom is.I've connected to my second PC at home and connected to the server. It works fine on local network. I restart network services (service network restart) and outside connections could be established.I have disabled iptables and ip6tables and after reboots it works fine. But PC is running without firewall.
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Jul 20, 2010
How do I get ufw to refresh firewall rules after accidentally running iptables -F
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Jan 26, 2010
Does anyone have tips about iptables rules for filtering network traffice?
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Mar 13, 2011
I'm trying to configure NFS sharing behind a firewall, I got it to work and all but I was caught by something that (to me anyways) seems odd.I've been able to mount the export on another computer and am transferring files over as we speak, but I'm just interested in knowing why the RELATED,ESTABLISHED rule seems to be catching almost all the traffic coming from the other node. Any ideas? Should I be concerned that my firewall isn't protecting anything or something?
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May 19, 2011
Whenever I add a rule to iptables, all of the policy counters reset. The counters for each individual rule remain intact, however, the main counter resets. Here's what I mean:
Code:
[root] ~ # iptables -vL
Chain INPUT (policy ACCEPT 65M packets, 83G bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 50M packets, 30G bytes)
pkts bytes target prot opt in out source destination .....
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Jun 18, 2010
The following is my setup. wireless server (ip of this server is 192.168.1.1) -- target board ( wireless client [ip of this is got for wireless server is 192.168.1.3 ] , bridge (192.168.36.1) )-- linux pc ( 192.168.36.3) as show above i have target board for that i have a wireless interface and a linux pc is connected to target board.now the ips are like this for linux pc 192.168.36.3 and my target board bridge ip s 192.168.36.1
my wireless interface got ip from another server like 192.168.1.3 ,now if i do ping on my target board for 192.168.1.1 it goes through wireless interface to the 192.168.1.1 wireless server.but when i do the same from target board connected linux pc its not pinging from linux pc i could able to ping to 192.168.1.3 but not 192.168.1.1 .I think i need to write a iptable rule properly on my target board to forward the 192.168.1.* packtes to wireless interface.
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Aug 15, 2011
I'm trying to build a firewall with IPTables: INTERNET <--------> (eth0) FIREWALL (eth1) <------------->FTP_srvI set all rules DROP by default.My rules for forwarding packet to FTP server:
#iptables -t nat -A PREROUTING -i eth1 -d $FIREWALL_EX_ADDR -p tcp --dport 21 -j DNAT --to-destination $FTP_ADDR:21
#iptables -A FORWARD -i eth0 -o eth1 -p tcp --dport 21 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
[code]....
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Jul 2, 2010
I two servers set up: 192.168.1.150 and 192.168.1.160 Initially, I want all traffic to be served by server 150. So for this purpose I am leaving the IPTables on .150 empty. At a point in time, I want to forward all incoming traffic to be served by .160 instead. I have accomplished this using these commands (on .150):
iptables -t nat -A PREROUTING -j DNAT --to 192.168.1.160
iptables -t nat -I POSTROUTING -j MASQUERADE
My problem is that if I have an open SSH connection to .150 (prior to adding the rules), the packets are still handled by .150 after adding the rules.. e.g. my SSH session stays active. I want these packets to be forwarded to .160, which would effectively disconnect the SSH session. I do not want the packets flat out dropped, I just want them forwarded on in whatever state they are in. If I try a new SSH session, it is properly forwarded to .160
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Oct 24, 2010
I have set up a master DNS server at 192.168.50.9 and a slave DNS at 192.168.50.6. Both servers are BIND9.Machines are for testing/experimenting, hence the IP addresses. Initially, the zone transfer was blocked by the firewall on the master, as the slave uses randomly selected non-privileged ports for zone-transfer query. So, as far as I understand, there are two possible approaches:
1. Allow connections based on source, which should be
Code:
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW,ESTABLISHED -s 192.168.50.6 --sport 1024:65535 --dport 53 -j ACCEPT
(and it works for me fine)
2. Allow ESTABLISHED and RELATED connections, which would be something like
Code:
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
which was my initial idea but didn't work, but has inspired me to dig deeper into firewall configuration topics :).
Question: Does zone change notification message count for opening a dialog, or notification from master and slave zone update request are two absolutely separate actions? If the latter is true, that, of course, explains why option #2 didn't work.
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Sep 23, 2010
I'm trying to configure Iptables and I just want to block everything but http/https. However, my connection is pppoe, so I have the ppp0 interface. Pretty much every Iptables tutorial that I found don't teach how to deal with this kind of setup. I'm forwarding the ppp0 to eth0 and I could configure the input rules and they're working. After this, I need to configure the output but nothing seems to work.
The current working rules are:
Code:
Chain INPUT (policy ACCEPT 7858 packets, 5792K bytes)
pkts bytes target prot opt in out source destination
299 201K ACCEPT all -- any any anywhere anywhere state RELATED,ESTABLISHED
0 0 ACCEPT tcp -- any any anywhere anywhere tcp dpt:www
0 0 ACCEPT tcp -- any any anywhere anywhere tcp dpt:https
11 820 DROP all -- any any anywhere anywhere
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 ACCEPT all -- eth0 ppp0 anywhere anywhere
0 0 ACCEPT all -- ppp0 eth0 anywhere anywhere state RELATED,ESTABLISHED
Chain OUTPUT (policy ACCEPT 10791 packets, 1951K bytes)
pkts bytes target prot opt in out source destination
I don't understand what those "state RELATED,ESTABLISHED" rules do. Also, I don't know if this rules are secure, because i'm very confused about the ppp0/eth0 interfaces.
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Apr 16, 2011
I am running Ubuntu server 10.10 and trying to setup iptables rules in /etc/if-up.d/iptables
Quote:
root@host# cat /etc/network/if-up.d/iptables
#!/bin/sh -e
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
Problem is that iptables doesn't get updated and I don't see them when iptables -L is executed after reboot.
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Sep 10, 2010
I have to make my final exam on network & security, my task is to compare Iptables and a firewall program, yeah not a distribution. I use Archlinux so I'd like to continue use it for my project! Anyway my question is: which Network firewall could be the best one? I need this features:
- packet filtering
- HA (High Availability)
- Live (active) connection migration (if one fails...)
- Load balancing (not really important but...)
I know "many" firewalls but they all are distro. I need something to install on a linux machine (as said... better if I can run it directly on Archlinux!)
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Apr 26, 2010
I am encountering problems to configure my firewall (through iptables) to allow apt-get features, like update and install.I have the latest debian server running in a virtual machine in my windows xp and therefore I have two interfaces in this debian server:- NAT Interfaceinet: 10.0.2.15- Host Only Interfaceinet: 192.168.56.101So far my iptable rules drop all packets for default, in exception icmp and ssh that I allow to ping and connect from my windows xp. Both of them I use only the Host interface (192...) to connect to another 192... interface on my windows.
Those are working fine, but apt is not. I know, in this very moment it shouldn't. But I made a lot of attempts trying to configure the iptables allow connections through the 80 and 21 ports from/to NAT and Host. I think I made all possible combination (or not, because it didnt work). But I'm wondering if someone more experient can help me solve this problem.
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Aug 13, 2009
I'm at my wits end at this point.
CentOS 5
iptables 1.4.1.1
APF 9.7
Webmin 1.4.80 (yes i can be a gui noob at times)
I'm currently running a dedicated server that hosts a couple of sites and runs a game server or two. I was using iptables on its own for a while, but recently I'm a target of all sorts of attacks (typically aimed directly at the gameserver on port 7777. UDP flood attacks, etc). I'm also seeing an spike in foreign spam, SSH brutes, and a few people in Turkey thought it would be cute to download files over and over and over I have decided to start banning entire countries, using the subnets listed here [URL]... I'm trying to block Central and South america (189,190,200,201.x.x.x), China, Ukraine, Turkey, Iran, Spain and Italy. I do this because a majority of the traffic from those areas are usually up to no good.
I installed APF so I could easily add these ranges in deny_hosts.rules and be done with it. I added the ranges, which turned out to be too many, and the system tanked. I decreased the amount of ranges to just 4:
189.0.0.0/8
190.0.0.0/8
200.0.0.0/8
201.0.0.0/8
Restarted APF and it loaded fine. Do an apf --list and iptables --list and it shows those 4 ranges as blocked. The only issue...I have people from 190.x and 200.x connecting to the gameserver and PLAYING. Its as if the firewall isnt there. Also, adding those ranges to /etc/hosts.deny (or whatever) doesn't block them either.
I add one of my own ips and I get blocked instantly. WTF?? I look in the iptables for webmin, and it shows an empty firewall. I do iptables --list and it shows the ranges I added in APF. I'm looking at building (or whatever its called) an fresh iptables with the geoip module added in. [URL]...
I've never done anything like this, and I don't want to kill the box. I also don't want to spend the effort if 1) something is wrong with my system to begin with and 2) the geoip module doesn't work. geoip module aside....how exactly should i configure the firewall? Empty iptables completely and then rely on APF for everything? Oh and heres another tidbit: I tried this before 2 years ago and it used to be that anything I put in APF would show when i looked at iptables using the webmin module. Thats no longer the case now. That was also on CentOS 4 when it did that. I don't know if moving to 5 is whats preventing it now.
In a nutshell, I'm new at this and I'm being inundated with terrible people trying to do terrible things and I'm ready to just give up. Can someone just give me a quick rundown on:
1) how to test that my firewall is actually firewalling
2) how I should configure the/a firewall on this CentOS5. Not too specific, I just want to know if I should empty iptables then load apf, should i not bother with APF (i like it when it works), is there a specific order of doing things?
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Nov 27, 2008
We have a new Bussiness DSL line with 16 public addresses.What we want is to setup a DMZ to run some services and internet to the LAN. Here's a schematic of what we want:
Code:
Backup Internet Main Internet
connection connection
| |
| |
SDSL Modem BDSL Modem
[code]....
The webserver has the following settings:
IP: 12.34.56.125
subnet: 255.255.255.240
gateway: 12.34.56.126
What IPTABLES rules do i need to setup to "see" all IP's in the DMZ-2 from the internet?
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Sep 17, 2010
I am facing a strange problem witht my iptables as there are some firewall entries stored somewhere which is displaying the below firewall entries even after flushing the iptables & when I restart the iptables service then the firewall entries are again shown in my iptables as shown below,
[root@myhome ~]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
[code]....
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Sep 28, 2010
I have managed to get iodine working between my ubuntu intrepid box and my windows client with a caveat.
The firewall rules allows DNS queries inbound. The client tunnel endpoint gets assigned an IP address and the tunnel is established properly.
However when I try to ping from the client machine, the reply packets are not coming back.
I used TCPDUMP on the Ubuntu box and watch the dns0 tunnel interface, and noticed that the packets are reaching the Ubuntu box from the client, but I don't see ANY ICMP echo replies until I turn off the firewall from Firestarter.
I see that outbound access rule is to allow all.
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Jan 14, 2011
is this possible on 2 Linux boxes will act as a INTERNET Firewall + Filtering: 1st PC = CENTOS 5.5 functions as a firewall using iptables with two NICS 1=ETH0 connected to internet with a public ip and 1=ETH1 with ip address of 10.0.0.1 connected to the 2nd PC Centos 5.5 with squid/dansguardian with ip address of 10.0.0.2
2nd PC = Centos 5.5 functions as a squid + dansguardian internet filtering with 2 NICS 1=ETH0 with ip address of 10.0.0.2 connected to the ETH1 of the 1st PC with ip address of 10.0.0.1 and 2nd ETH1=connected to LAN (172.16.1.0/24)
does this make sense? this might be confusing but I just want to try this, to protect incoming ssh from our previous Sys admins who intended to enter the LAN 172.16.1.0/24 network. And also to confuse them that they have to pass through 10.0.0.1 - 2.
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May 9, 2011
Can we use iptables as firewall instead of Juniper firewall
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Jun 4, 2010
I greet you at the same time ask me to help with a problem I have and I could not solve. Within the requirements I have is to connect a network that is connected by VPN to my LAN.The detail is I could have connection to the network by adding a network card (eth3) on the firewall and connect to the VPN router (DLINK) cable network, but I can not reach the other estin that are in the VPN.
It should be noted if I add a station within the network: 10.30.1.X/24 has no problems connecting with the other destinations.Physically this router is inside my 10.30.1.X DATA CENTER another wan.
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Aug 26, 2010
can I deny the access to my server for a specific OS? I have one PC which I want to give it acces from winxp, but if it's boot into ubuntu I want to deny all access to my server, same IP, same ethernet card
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May 9, 2010
I have a set of iptables rules generated by Firestarter, and i'm in the process of trying to familiarise myself with iptables itself, but there's one particular rule which is confusing me, perhaps somebody could explain it to me
My INPUT chain reads as follows:
Code:
Chain INPUT (policy DROP)
target prot opt source destination
ACCEPT tcp -- cdns01.plus.net anywhere tcp flags:!FIN,SYN,RST,ACK/SYN
ACCEPT udp -- cdns01.plus.net anywhere
ACCEPT tcp -- cdns02.plus.net anywhere tcp flags:!FIN,SYN,RST,ACK/SYN
[Code]...
Given that the firewall is actually blocking packets, it can't be this simple, so what am I missing?
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Sep 16, 2010
I am trying to program iptable rules for implementing a 1:1 NAT which does the following:
1. Forward all traffic from all ports on a public ip to a private ip
2. Forward traffic from a range of ports (x-->y) on a public ip, to a private ip
I did some google searches for the same, and came up with the following.
iptables -A FORWARD -t filter -o eth0 -m state
state NEW,ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -t filter -i eth0 -m state
state ESTABLISHED,RELATED -j ACCEPT
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