Iptables is a module that provides the Linux operating system functions of firewall, NAT and logging of data traveling over a computer network.

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Secondary NIC: what all can I do?

I was loaned a NIC which I promptly installed in my F16 workstation just to 'play' with it (using iptables and stuff). Other than forwarding packets from the new NIC to the old NIC using various ...
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1answer
512 views

Open a linux port without using iptables in Centos? [closed]

just a quick question, is it possible to open a port on linux Centos without using iptables? If so, how do I do that from the command line?
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2answers
3k views

IPtables: Blocking all traffic on an interface except select ports

I have four interfaces on my system (eth0, eth1, eth2, and eth3). I want to block all incoming and outgoing traffic on eth2 except for port 80 and 443, although I'm only worrying about 80 right now. ...
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106 views

How can I restrict my Virtual Machine using an iptables rule?

I am using CentOS Linux and am planning to setup a rule on my VM's iptable. I want to restrict all outgoing and incoming packets to the VM for a temporary period and allow only the DHCP packet to ...
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2answers
881 views

How to drop traffic before it hits existing iptables conntrack rule?

I am running an application that injects iptables connection tracking rules into the kernel so the machine can forward incoming UDP traffic to its destination as fast as possible. Some of the ...
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2answers
349 views

In Linux can I direct all traffic from a specific ip address or mac address to file

In Linux can I direct all traffic from a specific ip address or mac address to file. I am look of a way to take all traffic from a specific ip address or mac address and put it into a file. Does ...
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1answer
403 views

How can a PPTD VPN route traffic to other servers on network?

I a have a number of servers which expose various public services to the web. These are behind a server which is acting as a firewall using IPTables and forwards traffic to and from the servers. All ...
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1answer
4k views

Ubuntu 11.10 firewall/gateway - no client internet access

I have read many other posts but cannot figure this out. eth0 is my external connected to a Comcast modem. The server has internet access with no issues. eth1 is internal and running DHCP for the ...
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2answers
1k views

Using iptables to selectively route outgoing requests?

I'd like to set up my Dd-WRT firewall so that it uses the VPN service from a VPN provider to access a bunch of destinations and normal route foe all other requests. In detail: giganews.com would be ...
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1answer
244 views

conectivity problem

I have 2 PCs (anuin and hed), both running Linux that are connected via ethernet (192.168.1.1 and 192.168.1.3). Both PCs can ping each other. anuin is connected to the internet via an USB-stick ...
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1answer
351 views

iptables Settings as WAN Input for Router

I have an eee running ArchLinux with wireless access to the Internet. I want to use it as the WAN input for an Asus RT-G32 router into which it is hardwired. The router in turn is hooked up to a ...
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1answer
2k views

will the left|rightfirewall option of StrongSwan open UDP 500/4500 and protocol number 50 on iptable?

I know the StrongSwan use UDP 500 and 4500 for IKE traffic and IP protocal number 50 for ESP packages. I am not sure the usage of left|rightfirewall ...
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1answer
3k views

Remove port aliases in iptables

How can I make iptables show me port numbers instead of aliases for well known port numbers (eg. http for 80, https for 443 etc.). Is there a way to make it show just port numbers at all times?
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1answer
4k views

DD-WRT Setting Up Guest Network

I have a router on which I installed DD-WRT firmware. I am trying to set up a virtual interface to use as a guest network. The guest network should be on the 192.168.8.0/24 subnet while our LAN is ...
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1answer
485 views

Why small TCP connections succeeds, but big ones fails?

Sometimes from Linux system I see the following weird behaviour: I able to ping things and sometimes use some services, but networking is very bad. For example, now I routed connection through my ...
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2answers
2k views

Routing from the DMZ to the interior network only

I have a home network connected to Verizon's FIOS service. Verizon's ActionTec router is connected to the ONT via coax to establish the MOCA network. My DD-WRT router's WAN port is connected to one ...
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1answer
3k views

How do I block all ports except 22 and 80 in Fedora's iptables? [duplicate]

I am trying to only allow port 22 TCP/UDP and port 80 TCP/UDP from anywhere using Fedora 15 iptables, and all the rest will be never accessible nor scannable from a public network. But it never ...
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2answers
341 views

Blocking a botting URL to an Linux server running Apache

I have a webserver running OpenSUSE 11.1 and I need to block a URL. The reason I want to block a URL is because it seems to have a different IP address all the time, but the URL stays the same. I'd ...
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3answers
656 views

I need a traffic monitor for Linux, that only counts in a specific wireless network

I need a simple traffic monitor for Linux, that counts the traffic in a specific wireless network because I have volume restrictions on that one. I tried it using the following iptables rule: ...
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0answers
814 views

How do you add a MAC-based routing whitelist with DD-WRT and the OpenVPN client?

I have an OpenVPN client set up on my DD-WRT home router which maintains a VPN into my workplace. Slight problem: I don't want random lusers who access my wireless AP to have access to my company's ...
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1answer
522 views

Rackspace Firewall/Gateway Setup

I have rackspace account and wish to have this sort of setup: Firewall/Gateway eth0 - Public IP (56.X.X.X) eth1 - Private IP (10.X.X.X) Ubuntu 10.10. Accepts connections from the internet and ...
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3answers
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How to install firewall script in Ubuntu?

https://help.ubuntu.com/community/Router/Firewall In the link above there is a firewall script described. How can I install this script in Ubuntu 10.0.4 desktop?
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1answer
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Properly portforwarding the external IP with iptables

I am trying to forward all the incoming internet/LAN requests on port 80 to my local machine (running Apache), current iptables work (forward incoming internet traffic to my desktop, but if I try to ...
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1answer
584 views

Fedora 14 system-config-firewall-tui gone?

On Fedora I used to be abble to configure custom ports into the Firewall by going to setup and following the required steps till I got to something like this: Well that menu is here no more. I can ...
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1answer
951 views

iptables and NetworkManager on Ubuntu

I want to use iptables configuration on my Ubuntu 10.0.4 desktop, however I read that Network Manager and iptables have some conflicts. Should I uninstall NetworkManager? If yes, how? ...
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2answers
234 views

Blocking ports with iptables

I have a server with multiple interfaces (IPs). I'd like to block all ports on one of the IPs (I don't want to change anything for other IPs/interfaces), but allow outgoing connections from it. For ...
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246 views

Can ipmasq and ufw be used together?

If both ufw and ipmasq manipulate iptables, can I use ipmasq for a quick easy setup and then use ufw afterwards to add security or will the two just trample all over the iptables "stuff"? I'm playing ...
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1answer
93 views

Network problems that might be related to NAT

I have an odd setup where there is a router(Router 2) routing between network network 1 and network 2. One router(Router 1) with nat for internet access that routes between internet and network 1. ...
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1answer
476 views

iptables drop fake ip packets

I'm trying to drop all packets from the internet that use a fake ip address so they appear to come locally. Do I need both lines or only the first ? --append INPUT ! --in-interface lo --source ...
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2answers
392 views

iptables rules revert on Ubuntu

I'm using iptables on Ubuntu 10.04 and whenever I set iptables rules they will revert after a while. I set them with iptables -I INPUT or iptables -D INPUT and they work immediately and I see them in ...
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1answer
536 views

Save iptables when iptables-save doesn't exist?

I'm working on a Soekris net4801 that is running an unknown distro of Linux. The kernel is 2.4.29, and iptables is v1.3.4. I can't work out how to save the iptables. I searched the whole system for ...
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248 views

Fedora iptables error

I recently installed Fedora 13 and receive this Boot message: iptables: Applying firewall rules: iptables-restore: line 14 failed I am new to Linux and need help in figuring out how to fix ...
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3answers
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iptables restrict ssh session by mac address

I'm in the process of restricting access to my Linux production box, where ssh access needs to be limited to only a few MAC addresses. I've followed the instructions outlined in this guide and ran ...
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2answers
4k views

Setting up a Linux server with a public Static IP

I have setup a Ubuntu Linux server in an office. It should have a public IP so that outside users can access the internet. Currently, it is set with a public IP, but is it supposed to have a local ...
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1answer
258 views

One website not connecting over shared connection

A website is not opening on a computer that's connected via shared connection (not exactly "shared"). Pinging the website gets Packet filtered message. The setup of my home network is done by Ubuntu ...
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2answers
765 views

How evade firewall port blocking?

I have a serious problem with my institute's firewall. I have a Rackspace Cloud server instance that is configured to accept SSH connections on port 6xxx. When I was using port 22 there wasn't any ...
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1answer
867 views

Iptables prerouting and IP forwarding

I have a linux machine used as gateway for a Win XP machine. Both are in Virtual machine for testing purpose. Now I want to trick the Win XP user (me) with the forwarding of an IP address: I want to ...
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3answers
113 views

how do i set up this firewall?

i use fedora 13, and i have firewall turned off now. but i want to allow all incoming connections and outgoing connections except to a port P. i want to allow connection to port P only from certain ...
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2answers
440 views

iptables - router configuration

I have a router that I am customizing settings for. I want to only allow SSH from the internal network and drop everything else. This is what I have so far. I tried it and I had to reset my router ...
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1answer
588 views

Removing/Disabling Firewall on Linux CentOs seem to happen temporarily

I tried following the instructions in this link to disable and remove iptables firewall using commands: # service iptables save # service iptables stop # chkconfig iptables off # iptables -F # ...
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1answer
1k views

loopback error, home network

I've setup my router to forward port 80 through to my computer, so I can access it from a dyndns.org domain. The domain and the ip both seem to be totally working, externally (can access it from ...
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1answer
623 views

Quotas with iptables

pkts bytes target prot opt in out source destination 12770 2385K ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 quota: 2000000 bytes 0 ...
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1answer
928 views

Internal working of rules in forward chain for NAT

I am trying to understand how exactly NAT works to solve another bigger problem, here is my linux box setup: Interface eth0 connected to internet (public IP address) eth1 connected to local network ...
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1answer
402 views

Linux box acting as wireless access point to share the internet connection

A linux machine is connected to internet over two interfaces ppp0 and ppp1 using two modems. Also this machine acts as wireless access point through an interface say, eth0 with ip address 192.168.1.1 ...
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1answer
5k views

tc / iproute2, how to list the configuration

This is my first time using traffic shaping and I am wondering how I can list the rules I applied like you can with iptables? Walter
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1answer
332 views

how do I forward *only* http proxy across vlans?

My router has two bridges, br0 and br1. I'm sharing wifi access, and the guest subnet will be 192.168.2.x. The home subnet will be 192.168.1.x. I want all traffic destined for port 80 from the ...
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1answer
2k views

DD-WRT OpenVPN client - cannot get “lan” connected device to route traffic

I have OpenVPN client setup on DD-WRT openvpn small. client connects and can use traceroute to verify everything is tunneling out the openvpn connection. ip_forward is 1. iptables -t nat -A ...
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1answer
597 views

iptables firewall rules not allowing ssh from lan to DMZ

Chain INPUT (policy ACCEPT) target prot opt source destination REJECT tcp -- anywhere anywhere tcp dpt:www reject-with tcp-reset REJECT tcp ...
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1answer
517 views

IP Tables won't save the rule

I'm using ArchLinux and I have an IP tables rule that I know works (from my other server), and it's in /etc/iptables/iptables.rules, it's the only rule set in that directory. I run, ...
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539 views

Why does my Tomato router seem to behave badly as time passes

I've set up a Firewall script on my Tomato router (a WRT54G 2.0, actually) that seems to behave correctly at start, but after one or two days, it seems that the script does not work anymore... The ...