iptables allow creation of rules to define packet filtering behavior.

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1answer
366 views

No internet even with iptables ACCEPT all

I was trying to setup the firewall settings, and probably did something wrong. I don't have internet now unless I stop iptables service I tried flushing,and accepting everything sudo iptables -F ...
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4answers
591 views

What does this iptables command do?

Does iptables -I INPUT -j ACCEPT open all ports?
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3answers
4k 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. It's vital I catch ...
2
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1answer
3k views

Why does iptables still block my samba?

I'm currently fighting with iptables and samba. I read that samba needs ports 137-139 and 445 open on both tcp and udp. Here is the relevant part of my iptables config ... # forward valid incoming ...
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2answers
96 views

How can I allow SSH and SMTP only using IPTables?

I've got a raspberry pi set up to send me periodic emails. As it's connected to the internet 24/7, I need IPTables set up properly. I want to allow incoming SSH and allow emails to send out on port ...
2
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4answers
114 views

How can I lock myself out of a linux box with iptables?

In the Securing Debian Howto I read (about iptables): The tools can easily be misused, causing enormous amounts of grief by completely crippling network access to a system. It is not terribly ...
2
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1answer
639 views

Bad argument `127.0.0.1' in iptables

-A OUTPUT --destination ! '127.0.0.1' -m state --state NEW -j LOG --log-prefix "new_connection " --log-level 7 gives me Bad argument `127.0.0.1' What am I doing wrong? I used this docs : ...
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2answers
7k 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?
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1answer
3k views

system wide SOCKS5 Proxy

I connect to my Server on the internet using ssh -D 3128 user@rootserver.com. If I am right I thereby open a SOCKS v5 Proxy to my Server. Using firefox and FoxyProxy I can now add this to my proxys ...
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2answers
3k views

Remote SSH login not working

I have a PC behind a router with port forwarding setup Port 22 for SSH which works perfectly - I can login and everything. What I am trying to do is let this PC connect to a VPN and only allow ...
2
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1answer
3k views

iptables rule to allow access to internet

I made default policy of my machine- iptables -A INPUT -j REJECT #DROP ALL PACKETS TO INPUT CHANNEL INPUT channel has been blocked. Now I want to allow only some specific services like I should be ...
2
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2answers
780 views

List iptables rules as append command

A while back I was watching over the shoulder of a Linux guru and he issued a command that listed all the iptables rules in the format of the append commands you would need to issue in order to build ...
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3answers
60 views

Is there a command to deny an IP

Looking at the access log I found excessive access from an IP address. I then edit either .htaccess or .conf files to deny access from that IP. I wonder if there is a command or a oneliner that can do ...
2
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1answer
45 views

iptables to block all websites

I have Debian 7, and I want to block all websites in my computer, unless my email, using IPTABLES or others firewall. How can I block all website, include http and https too. How can I do this?
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2answers
97 views

Is it possible to have multiple virtual machines with the same (guest) ip on the same host?

What I try to achieve: Multiple virtual machines (virtualbox) on a Debian host which communicate with another server (not with each other or the host). All VMs need to have the same static network ...
2
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3answers
192 views

How to make Raspberry Pi to receive an IP from a router and also pass another IP to another device?

I know that I could achieve the desired result with an Ethernet switch, but I'm curious if I can get this with some cheaper solution. The idea is as follows: Rapsberry Pi has two Ethernet ports - ...
2
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3answers
374 views

What iptables command do I need to allow web server traffic?

I have a hard time understanding iptables rules. I am running a centos 6.5 VM on my laptop (vmware hypervisor) and it looks like it comes with this setup for iptables: # iptables -L Chain INPUT ...
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2answers
271 views

Temporary redirect ports

I need a temporary redirection of some ports to another machine. I've tried: iptables -t nat -A PREROUTING -p tcp --dport 4321 -j DNAT --to-destination 192.168.121.4:80 But shorewall blocks all ...
2
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1answer
111 views

Remove an IPTable Rule

I'm having troubles removing this ipables rule in Ubuntu: $ iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 3128 I've tried using the -D attribute but with no success. How can ...
2
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1answer
554 views

What does lo in iptables mean exactly?

I have seen countless examples of this rule in iptables: -A INPUT -i lo -j ACCEPT I thought lo means localhost (a.k.a. 127.0.0.1), but when I commented it out, I can't access the server using its ...
2
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2answers
5k views

FTP and iptables. Connection fails but ports are open

I installed proftp on my machine. With iptables disabled I can connect to the machine, using ftp-client or telnet. With iptables connection fails - telnet says "Connection failed" # works telnet ...
2
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1answer
249 views

Lost connectivity after iptables change

I attempted to add a couple web ports to iptables and in doing so lost the ability to resolve any external address. I have a working SSH session open and can get to the box easily if needed. Here's ...
2
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1answer
1k 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 ...
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2answers
1k views

Iptables port forwarding to qemu vm

Is it possible to create an IPtables rule that forwards all incoming traffic on port 80 on the host to port 80 of the qemu VM? Is such a scenario possible with qemu?
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2answers
10k views

Problems setting up TigerVNC and firewall

I have a box running a fresh install of Fedora 15. I've installed TigerVNC server on it and client on my Windows machine. I've added -A INPUT -m state --state NET -m tcp -p tcp --dport 5900 -j ACCEPT ...
2
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1answer
121 views

How iptables tables and chains are traversed

I know linux has 3 built-in tables and each of them has its own chains as follow: FILTER: PREROUTING, FORWARD, POSTROUTING NAT: PREROUTING, INPUT, OUTPUT, POSTROUTING MANGLE: PREROUTING, INPUT, ...
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2answers
70 views

What does this iptables rule mean?

Reading this article on how to configure OpenVPN, I see the following paragraph: Raspbian has a firewall to protect your Raspberry Pi from unknown and unexpected Internet sources. We still want ...
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2answers
361 views

Is there a specific reason why iptables would return an exit code of 3 (instead of 1?) when executed without sufficient privileges?

I simply forgot to use sudo: usr@arch ~[0] $ iptables -L iptables v1.4.21: can't initialize iptables table `filter': Permission denied (you must be root) Perhaps iptables or your kernel needs to be ...
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2answers
847 views

Bonding two broadband connections to serve LAN as a gateway

I need to increase the connectivity and speed of the Internet to my LAN users. These are the things I have in my hand to do so. PC with 3 NICs 1 for LAN and 2 for routers 2 broadband connections ...
2
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1answer
150 views

Do I have to swap IP sets, or can I add/remove on the fly?

I was wondering about the semantics of ipset(8). Is it possible to add a rule matching a set to iptables and then manipulate the set, or can I only create a set and swap it for an older set in order ...
2
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1answer
100 views

Should IP tables rules affect a serial port on Linux

I'm trying to setup some iptables rules on my embedded Debian Linux system, using a serial console I entered this: root@ts7600-47aad3:~# iptables -F root@ts7600-47aad3:~# iptables -P INPUT DROP ...
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2answers
376 views

RELATED,ESTABLISHED state in iptables

What do the words 'RELATED' and 'ESTABLISHED' individually signify in RELATED,ESTABLISHED state in iptables?
2
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1answer
124 views

Port forwarding using iptables on Linux

I want to forward a local port to a remote port (8041) to a port (8042) on a remote machine (10.0.0.42). I can do this via ssh -L 10.0.0.41:8041:10.0.0.42:8042 user@localhost where 10.0.0.41 is ...
2
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1answer
57 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 ...
2
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5answers
167 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 ...
2
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2answers
3k 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
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1answer
604 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 ...
2
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1answer
962 views

iptables rules too restrictive; Drupal webserver cannot access repositories, ntp or even websites

This is a Drupal website running Ubuntu 12.04 LTS on Linode. Someone recently changed our iptables rules and a number of problems started. These include: Our Mollom spam protection is not working ...
2
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1answer
444 views

Can iptables be used to convert a single-homed host into a NAT server?

Given: I have a machine (HostA) with only one NIC which has Internet connectivity. I have another machine (HostB) with one NIC on the same switch. HostB is not configured for Internet access yet. ...
2
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1answer
337 views

Explanation of bandwidth management script calling tc

I have some scripts in Linux to manage internet bandwidth, but I do not understand what they do. What is the meaning of the following scripts: tc qdisc add dev $IF root handle 1: htb default 256 tc ...
2
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1answer
468 views

iptables is not blocking

I have a script running every minute by a crontab. This script scans the system logs and grabs the IPs of every failed attempt to login on the server's dovecot, exim or ssh and add them to an ipset, ...
2
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1answer
525 views

IPtables command shows libipt_random.so missing

When I run a command, it shows error. I searched on net, but no one give me the correct answer. Googling shows only wrong answers for this questions. So please help me to overcome this problem. ...
2
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2answers
665 views

Is xinetd still the best method to let non root daemons listen on privileged ports?

When I need to use SNMP monitoring for java applications, there is the need to that application (usually ran as daemon user) to listen on snmp port. If there is no other alternative, of course I can ...
2
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2answers
1k views

How can I Forward a subDomain to a specific port?

My apologies if this has been asked before. I haven't found an adequate solution so... yeah. When a specific domain, "example.com" is accessed, I want it to act normally. In other words, it should go ...
2
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1answer
3k views

Port Mirroring using iptables - copy all traffic among nginx on :80 and apache on :8080

I have nginx running on port 80 and apache running on port 8080 I want to transfer all the traffic to both nginx and apache asynchronously i.e the performance of one server wont be dependent on the ...
2
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1answer
9k views

Fedora 16 - Iptables installed, but no iptables service available

I'm trying to open ports on my fedora OS. In the past, this was as easy as adding an rule like -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT I went to restart my iptables ...
2
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1answer
1k views

What does this iptables entry mean?

iptables-save output: *filter :INPUT DROP [2929:172650] :FORWARD DROP [0:0] :OUTPUT ACCEPT [74596344:6265371965] These are the opening lines of the iptables-save command. What do the numbers in the ...
2
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1answer
2k views

Unable to make outbound SNMP connections when IPTables is enabled

I have a bunch of windows servers configured with the windows SNMP agent. Each server has four IP addresses and SNMP listens on all of them. There is something very odd with my monitoring server ...
2
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1answer
21 views

Use two SSH ports, but open only one?

My iptables.conf looks loosely like this: -A INPUT -p tcp --dport 65000 -j ACCEPT -A INPUT -j DROP My sshd_config looks like this: Port 22 Port 65000 #AddressFamily any #ListenAddress 0.0.0.0 ...
2
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1answer
72 views

How to Mark Traffic using IPtables?

I'm trying to mark traffic, How shall I write following code in terms of IPtables? /ip firewall mangle> add chain=prerouting src-address=10.1.1.1/32 action=mark-connection \ ...