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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How to unblock jabber on TI ADSL router with iptables

I have old but reliable Texas Instruments ADSL router. Board AR7RD; BUILD=061005; VERSION=3.7.1 If that matters... One thing that bothers me is that it somehow blocking my jabber (Pidgin ...
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IPTables - unknown error 4294967295

I've moved an old Slackware 11 installation from a physical PC to a virtualized in ESXi. Everything seems to work fine except for one rule in iptables, namely the row: iptables -t filter -I INPUT -m ...
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Access Apache server running in Fedora guest VirtualBox from host

I have trouble accessing Apache server from host. I’ve Fedora 15 VM VirtualBox installed on Windows 7. Within this VM I have Apache server running and working fine within the guest. Not sure what ...
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236 views

amule, Fedora 14, iptables

I need to set iptables rules for aMule, but I am not sure which one are the right ones. Googling around, I have seen something like: iptables -I INPUT -p tcp --dport 4662 -j ACCEPT iptables -I ...
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How to “shut off” all networking on Linux from bash?

I'd like to write a bash/shell script that "turns off" the machine's ability to communicate over it's network card, effectively shutting down all networking. From the command line: # To turn all ...
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872 views

how to telnet redirect ip and host using iptables

I try to telnet from PC 3 To PC 1 and it's redirect to PC 2 PC 1 : 192.168.0.1 PC 2 : 192.168.0.2 PC 3 : 192.168.0.3 i have command like this in PC 1: iptables -t nat -A PREROUTING -p tcp -d 192....
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What is command to look list of redirect rules, iptables

im using command like this : iptables -t nat -A PREROUTING -p tcp -d 192.168.1.118 --dport 4080 -j DNAT --to-destination 192.168.1.118:4088 My question what is command to look all rules in the ...
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How to route specific traffic through OpenVPN?

I'm running a server at home with rtorrent and apache2. I would like to route my rtorrent traffic via OpenVPN and since im kinda new to OpenVPN and iptables i would like to have a user friendly guide. ...
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2k views

iptables port based routing

I've been Googling this for days with no success. I connect to a VPN from my server from time to time and I'm trying to configure my Debian server to only use port 80 and 443 through the VPN and all ...
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118 views

why does this iptable rule work at a specific position in the chain

I'm running OpenWrt on my router, which allows me to run applications such as apache and emule. I installed emule but I keep getting lowid, indicating that my port is misconfigured. I was able to ...
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No output returned when curl ing any URL in Red Hat 6 but the same url works in lynx browser

I am trying to install some packages in Python using easy install. But i get a 'Download Error' for any package i try to install. So i tried to test if internet is accessible at all from the machine (...
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5k views

How to route specific traffic through OpenVPN?

I'm running a server at home with rtorrent and apache2. I would like to route my rtorrent traffic via OpenVPN and since im kinda new to OpenVPN and iptables i would like to have a user friendly guide. ...
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3k views

OSX: Mimic Ubuntu IP Masquerading via iptables with ipfw

Good day, I am attempting to replicate a setup I have between a router and an Ubuntu PC, and have the same setup working on my MacBook (10.6, Snow Leopard). First, I have a router that has a USB ...
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462 views

How to resolve conflict in iptable rules

In Ubuntu 12.04 and above there are no iptable rules defined by default. I added the following rule and it works fine:(Update) iptables -A INPUT -p tcp -j QUEUE -m string --string xyz --algo bm Now,...
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238 views

1:1 NAT IP address using iptables

Suppose I have 2 internal networks: 1.1.1.0/24 and 1.1.2.0/24 I would like to NAT a specific IP address from one network to the other, in which the new address would be obtained via DHCP. For ...
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739 views

MIxing RFC1918 NATed and public IP addresses using IPTABLES

I wish to host a SIP server and DNS at the end of an ADSL2 connection. My current network sits behind an iptables firewall which runs on a Linux box with two Ethernet interfaces, the WAN interface (...
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117 views

IPTables Allowing Access without Rules

I'm sure this is mostly my misunderstanding of how iptables works, but I've set up some rules... -A INPUT -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT -A OUTPUT -p tcp --sport 22 -m ...
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How to configure port forwarding for an IP camera

I need to configure port forwarding for my IP camera so that I can access it from internet. UPNP is not supported on my gateway. My network configuration is the following: Gateway (Ubuntu Server 12) ...
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How to route the incoming connections through a specific interface?

I have multiple ethernet cards with two different set of networks configured on them. The output of route -n is given here:: Kernel IP routing table Destination Gateway Genmask ...
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4k views

Load balancing with multiple gateways

I have to different ISPs, each on each own network. The main connects via ethernet and the secondary via wifi. The two networks have no relation at all. I just connect to them simultaneously. The ...
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need to route the traffic through a specific network card

I have two network cards and they both have a different network. I need the outgoing connections to go only through a specific network card. Any help ? Update: I ran a route -n command and got this ...
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327 views

Why does Firefox need a loopback connection?

I was playing around with firewalls and iptables. When I blocked any traffic except HTTP and DNS I was able to establish a connection to google.com via wget google.com. But I wasn't able to open ...
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941 views

iptables block everything except http

I'm trying to configure my iptables to block any network traffic except HTTP: iptables -P INPUT DROP #set policy of INPUT to DROP iptables -P OUTPUT DROP #set policy of OUTPUT to DROP iptables -A ...
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Centos iptables blocks after reboot

I have a Centos5 installation with kvm on my server. I am using nat portforwarding to ssh my virtual machines. I have several iptables rules and saved then in /etc/sysconfig/iptables. After reboot, I ...
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338 views

IP forwarding with iptables

Suppose there are hosts A and B. A is allowed SSH access to B based on its IP address. Consider now another host C. C does not have access to B, but if we could route its traffic through A, then C ...
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CentOS 6 - iptables preventing web access via port 80

I'm setting up a new web server with CentOS 6.2 and am not able to connect via the web. Everything looks set up correctly in httpd.conf and Apache is running, so I'm assuming it's an iptables issue. ...
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293 views

dd-wrt: Keep source ip after port forward

I just started using dd-wrt on my wndr3700, but now all my incomming connections to a server inside the network gets the same source ip as the router. How can I change this back so I get the real ...
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644 views

Different routing rules for a particular user using firewall mark and ip rule

Running Ubuntu 12.10 on amd64. I'm trying to set up different routing rules for a particular user. I understand that the right way to do this is to create a firewall rule that marks the packets for ...
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384 views

IP tables gateway

I am trying to make an iptables gateway. I ordered 3 dedicated server from my hosting company all with dual nics. One server has been given all the ip addresses and is connected directly to the ...
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1k views

Pinging an external server through OpenVPN tunnel doesn’t work

I have an OpenVPN server and a client, and I want to use this tunnel to access not only 10.0.8.0/24 but the whole internet. So far, pinging the server from the client through the tun0 interface works, ...
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306 views

CSF Unresolved issue

I began receiving service failures for CSF/LFD once the limit was reached in iptables preventing the service from working properly. I flushed all iptables rules, and redid by rules using CIDR rather ...
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iCloud stuff stops working while connected to OpenVPN

I have a fairly simple OpenVPN setup on an OpenVZ VPS with Ubuntu 11.10. Client is the Viscosity client on Mac OS X 10.8.2, and after some testing, we can rule out the client as being part of the ...
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335 views

Load-balancing: response packets not routed - iptables

I have a problem with iptables. I'm trying to setup a load balancer between 2 uplinks. I can mark packets and connections, use ip rule to choose routing table (so changing the gateway). But, when I ...
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777 views

Packets marked by iptables only sent to the correct routing table sometimes

I am trying to route packets generated by a specific user out over a VPN. I have this configuration: $ sudo iptables -S -t nat -P PREROUTING ACCEPT -P OUTPUT ACCEPT -P POSTROUTING ACCEPT -A ...
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70 views

Is there an alternative of TrivialProxy for linux?

Does anyone knows an alternative software of TrivialProxy for linux? iptables is not enough because I need a GUI. Thanks in advance.
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Routing table on Linux not respected

I have a very specific problem, building a Linux VPN endpoint (with external VPN Gateway), which should route certain networks over the tunnel, others via default gateway. The Linux VPN should do a ...
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467 views

Rate limiting traffic between specific hosts (based on their MAC) using iptables

I have setup a simple isolated network consist of following Linux based machines (simplified example): Node1<---->Router<---->Node2 Router's eth0 is connected with Node1's eth0. Router's eth1 is ...
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678 views

Reasons why ports below 1024 cannot be opened

I'm root on a machine I don't know how it was configured. I try to open SSHD on another port than 22 but it does not work. I changed the /etc/ssh/sshd_config file and added a new Port line extra to ...
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796 views

Difference default setting on iptables between CentOS 6.3 and Ubuntu 12.04

I would like to ask in ubuntu 12.04, there is no firewall settings by default? iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (...
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Is there a decent diagram of packet flow for a modern era (2.6+) iptables setup?

I'm currently trying to debug a particularly hairy set of DNAT based iptables rules (the UDP reply never makes it back to the original requester) and I'm struggling to visualise the packet flow ...
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79 views

iptables -L lags on non localhost or anywhere address

I am trying to configure iptables for ubuntu 10.04 and I have a problem with iptables -L lagging on rows where the destination or source address is not localhost or anywhere. The following entries ...
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5k views

Reverse Proxy for TCP (RDP, VPN, etc) and HTTP

I have a domain that points to my ISP assigned IP though a CNAME (cname goes to my noip address incase my ISP decides to change the IP), I would like to route different subdomains to various IP:PORT ...
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130 views

iptables rule cannot be added

Is there anything wrong with these rules? They cannot be added to iptables, no error but they just don't show up in iptables -vnL iptables -I FORWARD 1 -s 1.2.3.4 -p udp -m connlimit --connlimit-...
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Will increasing number of rules in iptables slow down my internet

How much impact will the rules have on speed, if we are using match to queue the packets.
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409 views

internet connection gone after $ iptables -F INPUT

I have a PC with two Ethernet cards, and I was trying to configure my eth1, but when I typed $ iptables -F INPUT, the internet was gone on eth0. Does anyone has any idea how to get my internet ...
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2k views

Match multiple strings in iptables

I have 2 strings, and i wish to queue the packet if it contains both the strings ( something like ("jsh"&&"gjhyg")), i tried following ways, but they don't seem to work: sudo iptables -A ...
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How to redirect local connection to my things in IPv6 on linux?

With IPv4 I can make some program connect to my service instead of where it wants using REDIRECT and DNAT targets in OUTPUT chain in iptables (sometimes combined with -m owner) In IPv6 hovewer I don'...
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219 views

Is it possible to figure out which http request generated the corresponding response

I am using iptables to listen to tcp (http) packets. I am filtering out INPUT responses containing a matching string. Is it possible to know which http request generated the response. Assuming 10 ...
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340 views

iptables: understanding the rationale behind its tables and chains

I'm going through the iptables tutorial and am currently at Chapter 6, Traversing of tables and chains. I'm having trouble understanding the why's behind Tables 6-1, 6-2, and 6-3 listed in the above ...
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146 views

Separating two networks

I have two routers, R1 and R2. R1 (a stock linksys router running dd-wrt) is connected to internet and is serving internet to a network of 5 devices/PCs running a DHCP server, with a network of 192....