iptables allow creation of rules to define packet filtering behavior.

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2
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1answer
106 views

Mark packets between machines (client and router)?

Can I mark a packet on the client's OUTPUT chain and add an iproute policy on the router to route them via a specific gateway? This what I tried to do, but it isn't working. My client's mangle table ...
3
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2answers
422 views

iptables port forwarding

I have a CentOS server with Java/J2EE(Tomcat) installed on TCP port 8080. I have two interfaces, eth0 and lo. I need to forward all incoming connection on TCP port 80 to 8080. I tried doing the ...
0
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2answers
209 views

Isolate a hosts networking with iptables

I want to isolate a host on my home intranet using iptables on my linux router. So say for instance, I have a host that has the IP of 10.0.1.50 and I want it to be able to talk to the rest of the ...
2
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1answer
51 views

How would I go about making this IPTABLE rule for every ip and not just one?

iptables -I PREROUTING -t nat -p udp -s 192.168.0.62 --dport 53 -j DNAT --to-destination 23.21.182.24 Instead of 192.168.0.62 I'd like to set that as a global rule, EVERY ip that needs dns should ...
4
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1answer
2k views

How can I redirect all traffic except local through external proxy with iptables in dd-wrt?

I have a router with dd-wrt. I have a firewall running to direct all traffic through an external proxy. It works great except that it also redirects local Ips and my proxy does not allow Ips, so I can ...
4
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1answer
83 views

iptables change log

Somehow an iptables rule was added to one of my systems. Does (or can) iptables keep a log about when and (maybe) who made a rule change? If iptables itself can't, is there a wrapper that might do ...
2
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0answers
200 views

SNAT problem in iptables

I am trying to reroute traffic from specific devices in my house over openvpn. For this, I've created an OpenVPN tunnel between my house wifi router and my server. Here is my setup: Wifi router's ...
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3answers
1k views

How to change user agent on all http requests made from my machine with Squid intercepting proxy?

I'd like to change the user agent on all HTTP requests made from this machine. It's easy enough to change the user agent in each browser, but other apps also make http requests. In particular, there's ...
2
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0answers
145 views

IPTables dropping UDP packet stream

I have a configuration where UDP packets containing encapsulated DNS data are sent to a KVM instance for processing. The KVM instance sits behind an IPtables firewall which is also doing NAT. The ...
3
votes
1answer
251 views

IPtables : Limit number of new ssh connections per minute

I need to ensure on my server that maximum new ssh connections per minute are not more then 5. sudo /sbin/iptables -A INPUT -p tcp --syn --dport 22 -m connlimit --connlimit-above 5 -j REJECT Above ...
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3answers
3k views

Help configuring a custom log file for iptables

I'm trying to log dropped packages to a custom file instead of /var/log/messages. To achieve this, I have added these two lines at the end of my configuration file: -A INPUT -m limit --limit ...
1
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1answer
361 views

Why iptables does not fetch information from /etc/sysconfig/iptables on centOs?

I'm new in Linux and encountered with problem with iptables. Here is content of /etc/sysconfig/iptables file # Generated by iptables-save v1.4.7 on Tue Nov 27 21:41:04 2012 *filter :INPUT ACCEPT ...
1
vote
2answers
167 views

Saving iptables on CentOS, and merging the previous rules with the newly saved ones?

I added some new rules using iptables command, then saved them using /sbin/service iptables save as described here: http://www.centos.org/docs/4/html/rhel-rg-en-4/s1-iptables-saving.html After ...
1
vote
0answers
88 views

SNAT with network alias IP RHEL 5.5

I have Rehat Enterprise Linux Server Release 5.5(Tikanga) with two interfaces as below eth0: with public IP as xxx.xx.64.118 eth0:0: with public IP as xxx.xx.116.19 eth1: with private IP as ...
2
votes
1answer
1k views

Set up firwall with iptables to only allow VPN

Im using IPredator VPN with openVPN and I want to make sure that if the connection is dropped, i wont submit data from the internet without the VPN. I heard that I could do that with iptables and a ...
1
vote
1answer
43 views

IPTABLES chain need help for restriction

I have two network cards eth0:- 172.16.91.70 (External Zone) eth1:- 172.16.85.70 (Internal Zone) I have clients in my Internal Zone which can access the external network. The ping goes fine and can ...
8
votes
1answer
1k views

Linux as router with multiple internet providers

Linux as router: I have 3 Internet providers, each with its own modem. Provider1, which is gateway address 192.168.1.1 Connected to linux router eth1/192.168.1.2 Provider2, gateway address ...
2
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0answers
254 views

Iptables and Port Scanning and Recent module

I'm trying to write an adaptive firewall using iptables, and am not clear on how the recent module is working. For example, see http://blog.zioup.org/2008/iptables_recent/ Snippet from my iptables: ...
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2answers
182 views

IP packets have wrong source address

I have two 4g modems connecting to a network and sending and receiving data. There is a problem though, as the modems keep getting kicked off the network because the source IP address of the packets ...
0
votes
1answer
65 views

Undoing specific iptables ip/port restriction

Say I add the following iptables rules: iptables -A INPUT -p tcp -s localhost --dport 4444 -j ACCEPT iptables -A INPUT -p tcp --dport 4444 -j DROP This allows localhost to access port 4444 then ...
2
votes
1answer
424 views

Port Forwarding using iptables on Open-Mesh

A quick overview for those who are unfamiliar with Open-Mesh: The system uses small wireless access points that automagically build their own mesh network. As long as one of the access points is ...
1
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1answer
128 views

Redirecting all IP over USB traffic to a fixed address

I'ma bit of a network newbie, so apologies for the inaccurate vocabulary. Say I have a device connected by IP over USB to my computer (running Ubuntu), that connects to 10.0.0.1. I configured my ...
2
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2answers
2k views

Debugging iptables using live packet views

Are there any CLI or GUI functions that I can use to monitor hits to iptables and watch as packets interact with iptables?
4
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2answers
5k views

How can I redirect outbound traffic to port 80 using iptables locally?

I'm trying to locally redirect ports on my Ubuntu machine using iptables. Similar to transparent proxying. I want to catch anything trying to leave my system on port 80 and redirect it to a remote ...
2
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0answers
152 views

LAMP Hardening, Transparent Proxy with iptables

I'm running a LAMP server with FTP(S) and several users. The users have only access to uploading PHP files and other web content. Some are running Drupal and Wordpress, but also a few home made stuff. ...
1
vote
1answer
176 views

Intercept incoming TCP/IP packets on Linux and perform NAT

I want to make a decision of what computer is behind the firewall sending the packet. Imagine I have 2 PCs behind the firewall and I want to, based on (my algorithm), make a decision at the firewall ...
1
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2answers
241 views

iptables: what the difference between filter and mangle

I am using iptables to to mark the package and want to route based on the marks. First I added the ip rule: sudo ip rule add fwmark 1 prohibit (The "prohibit" is just for test, I will change it ...
0
votes
1answer
226 views

Allowing a domain name in my IP Tables

I have a Linux server that gets a time offset for some strange reason. I set up cron job to run and update the time using the following command: /usr/sbin/ntpdate pool.ntp.org The problem is the ...
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1answer
195 views

I can't access my computer through specific port?

On Fedora I tried to access port 1521, so I opened the following port on my firewall: $ sudo iptables -I INPUT -i eth0 -p tcp -m tcp --dport 1521 -j ACCEPT $ sudo service iptables save I then tried ...
2
votes
1answer
289 views

iptables string not dropping packet from tcp streams while using conntrack and string

I'm facing an unusual issue where specific TCP steams are not getting dropped by iptables; instead it's like iptables is just removing those specific packets. We're getting the following traffic: ...
1
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2answers
680 views

Missing iptables file on directory /etc/init.d/ (Fedora 17)

Is the iptables file in Fedora 17 moved from /etc/init.d/ to /etc/sysconfig/? I need do some patching to the iptables file to solve the firewall problem (Setting chains to policy ACCEPT: security raw ...
1
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1answer
210 views

port forwarding to internal lan server

I've ppp0 --> eth1 and eth0 (internal lan). I need forwarding externel 10022 port to port 8999 of the server 192.168.1.254 iptables -t nat -A PREROUTING -p tcp -i ppp0 --dport 10022 -j DNAT --to ...
3
votes
1answer
1k views

iptables: how to allow traffic from redirected port

I have a web service running on debian 7 and listening on port 8080. I want to redirect 80 to 8080 for inbound connections and allow only port 80. Here is my iptables configuration: root@localhost:~# ...
1
vote
1answer
279 views

What does the route Dest: 123.123.123.123, GW: 0.0.0.0 mean?

I have a route table: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 123.123.123.123 0.0.0.0 255.255.255.255 UH 0 0 0 ...
3
votes
2answers
721 views

What is the tun network interface for?

I noticed when running ifconfig that there is a network interface called tun0 and it has an ipv4 address. A bit of research shows that it is a tunneling device, but I don't really know how it's used, ...
1
vote
1answer
805 views

Copy/Mirror traffic to WAN interfaces without “iptables tee” support

I want to copy every outgoing packet to other WAN interfaces but my iptables (v1.2.7) doesn't have TEE target support. I wonder if there is another way (maybe using iproute2 or ebtables) to copy every ...
2
votes
1answer
2k views

How to setup iptables rules to allow skype

Here are my iptables rules to allow Squid to connect to a web server: # Accept internally-requested input iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT #http,https traffic only ...
2
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5answers
154 views

Difficulty setting up iptables

I'm very new to *nix operating systems, and I'm having some trouble which I believe is because of misconfiguration of the iptables firewall. My server has SSH running on port 22, and server software ...
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2answers
564 views

SSH tunneling through a busybox router

I have a busybox router and I'm able to login to the console using telnet & I also have access to the web interface. My question is, how can I create an ssh tunnel from my local network through ...
1
vote
1answer
622 views

How to log iptables as of kernel 3.9.0?

What is the right way to log iptables as of kernel 3.9.0? I can no longer append a logging rule such as: # iptables --new-chain droplog # iptables --append droplog --jump LOG --log-level info ...
2
votes
2answers
1k views

Why must loopback traffic be authorized using iptables to get web access?

I thought the following was necessary was necessary for outgoing HTTP on a desktop (non-server): iptables -A INPUT -p tcp -m multiport --sports 80,443 -m conntrack --ctstate ESTABLISHED -j ACCEPT ...
2
votes
1answer
317 views

IPTables string match redirection

The issue: I am currently redirecting port 80 requests to another system on port 1000. This is done like so: iptables -t nat -A PREROUTING ! -s 172.20.1.2 -p tcp --dport 80 -j DNAT --to-destination ...
1
vote
1answer
109 views

How to relay packet in a wireless ad hoc network?

I am trying to connect several Linux computers in wireless ad-hoc multicast : -computer C1 (192.168.1.3) -computer C2 (192.168.1.5) -computer C3 (192.168.1.6) C1 can not reach C3 On computer C1, ...
2
votes
1answer
2k views

Log the dropped packets by IPTables only if its DROPPED by a specific rule

I have IPTables rules set on a Linux device. I have a particular rule to drop the packets, and I wish to log the packets only if they're dropped by that specific rule, and not by the other rules. ...
2
votes
0answers
253 views

TPROXY for redirecting UDP on arbitrary ports

I want to intercept all UDP traffic leaving tap1. And possibly reply to e.g. DNS-requests. To accomplish this I wrote some python code listening to localhost and use iptables with a rule-set like ...
4
votes
2answers
156 views

Is it possible to set-up a VPN in such a way that I disconnect from the Internet if it goes down?

How can I set-up a VPN so I loose connection to the Internet if it goes down? I use Ubuntu and have used the network-dialog to use a VPN; but if the VPN goes down, it just switches to the non-VPN ...
1
vote
1answer
87 views

netfilter's configuration to allow openvpn

I've got a debian server at home, that I use to have a VPN access to my home computers. I've redirected the openvpn port on the port 2000 : in my file "server.conf", I've added this : #Server mode ...
3
votes
2answers
681 views

Open and redirect port

I'm trying to set up SNMP for a router so I can monitor it from an existing Nagios installation on an off-site server. I'm having trouble getting the router to respond to SNMP requests from the WAN, ...
0
votes
1answer
128 views

IP Address inaccesible

My Linux machine is inaccessible by the IP address, as in only http://127.0.0.1:8080/projectname or localhost works on the browser, but http://10.1.5.5:8080/projectname doess not (here ...
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1answer
569 views

How does iptables MASQUERADE work on the incoming side?

I'm still reading the iptables manual page and other documents and digging around questions and their answers. This is the problem which arises. When we setup the NAT we use a POSTROUTING rule such ...