Iptables is used to set up, maintain, and inspect the tables of IP packet filter rules in the Linux kernel.

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Configure port forwarding from localhost:x to z.z.z.z:y without root

Our application needs to configure simple port forwarding on runtime. I'm talking about an iptables configurations like this: iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE iptables -A FORWARD ...
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13 views

Is it possible to Disable TCP Sequence Number Checking in Ubuntu?

I want to disable TCP Sequence number checking in Ubuntu. I suspect that Ubuntu is dropping packets as Wireshark shows that the Packets arrive out of order. Is there any such feature in Ubuntu or ...
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10 views

iptables: route all traffic from wlan over VPN

I do have a PC with one ethernet and one WIFI connection and would like to route all traffic that comes through the WIFI over a VPN. How can I do this with iptables? So the setup is: ...
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14 views

Why iptables has pre-up and post-down rules

Why the iptables has post-down rule and pre-up rule? Is it necessary to have 2 rules instead of just one pre-up rule? https://help.ubuntu.com/community/IptablesHowTo auto eth0 iface eth0 inet dhcp ...
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17 views

mirroring traffic with iptables doesn't work

i want to mirror specific traffic to ip 192.168.200.1 i use this solution : Mirror Port via iptables but when i enter following command, error occurs: iptables –I PREROUTING -t mangle -j ROUTE --gw ...
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41 views

vagrant, port forwarding, and iptables

Background: I am a newby learning Python and Django. Because my machine is Windows 8.1, I installed Vagrant with Precise 64. At first things were fine, then suddenly, NONE of my projects in the VM ...
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24 views

Connection refused - despite iptables rule is accept and port is open

I am trying to setup an ssh service. I am behind a residential router, and connecting to the desktop on a laptop computer. I use the the local IP of the desktop (192.1 ...) for address. The ...
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1answer
27 views

keep iptables up to date

I've installed iptables-persistent (Ubuntu 14.04) with the impression that it automatically saves iptables on shutdown but that appears not to be the case? It seem to load saved rules at startup but ...
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1answer
21 views

iptables-persistent not uninstalling

I'm running Ubuntu 14.04 and I simply want to uninstall iptables-persistent to test something. As suggested here ...
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1answer
23 views

Differences between UFW and GUFW

From what I have been able to piece together, the firewall that comes with Ubuntu is iptables, which is very complicated, so an easier way to access the firewall is through UFW and GUFW. UFW is ...
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45 views

Why aren't these ufw rules working?

I'm trying to configure ufw to only allow connections to 3 ip addresses on my local network, and deny everything else. Here's the commands I'm using: yes | sudo ufw reset sudo ufw default deny sudo ...
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1answer
45 views

Why is iptables getting double rules?

I have a server running Ubuntu 12.04. A couple of reboots back I started noticing that iptables rules get doubled upon reboot. This is what I get after a reboot (with added line breaks): $ sudo ...
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UFW - Ubuntu Firewall - Banned IP address. How do I remove?

Currently I can't access my server remotely unless i turn off my ufw (ufw disable). I added my IP to the ufw accept rule, but it still doesnt work for some reason. Below are some of my screenshots. ...
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1answer
63 views

What are the IP addresses in my iptables chain FORWARD settings in a Dokku/docker setup?

I've been playing around with Dokku on DigitalOcean (following this guide) and I'm trying to understand current firewall settings. So here's my setup: Ubuntu 14.04 Dokku Docker (as part of Dokku) ...
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1answer
64 views

How do I write an iptables rule to limit Internet bandwidth usage of user or IP address

How do I control or limit Internet bandwidth usage of users/computer/IP address in network with the help of iptables rules? I have one static IP address which provides Internet (that is, WAN). I ...
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0answers
17 views

Unable to access shared internet connection

Thank for reading my post. I have setup Ubuntu 12.04 server on an unused box. My idea is to use it for development and as a router. I have 2 network cards installed. eth0 is connected to my ADSL ...
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78 views

Creating routes using iptables in ubuntu 14.04

I'm a newbie at ubuntu's administration although I've been using linux for a while just at user level. Let's show my problem. This is my network (only static IP addresses are used, for both private ...
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1answer
42 views

keep getting added to hosts.deny + iptables

I am confused to why this has started to happen. On my local network, if I click 10-20 apache/http links my server will decide to add me hosts.deny file and block me on iptables. Its not just ...
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1answer
73 views

How to use multiple IP block list in Ubuntu peer 2 peer programs?

I would like to use several public IP block list (IP filters) in qBitTorrent or Vuze, on Ubuntu 14. What is the easiest way to do that and to get the lists updated? Note: This is not a discussion ...
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1answer
35 views

Ubuntu wifi hotspot cannot share network

I am using hostapd for my WiFi hotspot, and I can connect my WiFi perfectly until today. I have isc-dhcp-server and bind9 running on my laptop, because I want my laptop to be dhcp and dns server. ...
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1answer
87 views

How to open the ports on firewall in Ubuntu? [duplicate]

I'm pretty new to Ubuntu. I just want to open the most common ports namely FTP (port 20 TCP/UDP) HTTP (port 80 TCP/UDP) SMTP (port 25 TCP) ETC I've tried all the ways in iptables, ufw, and gufw. ...
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33 views

Iptables Issue can't SSH Remote Machines

I want to SSH to 192.168.1.15 Server from my machine, my ip was 192.168.1.99 Source Destination was UP, with IP 192.168.1.15. This is LAN Network there are 30 Machine's Connected to the network and ...
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42 views

Unable to connect to Chromecast

I seem to be having a problem connecting to Chromecast from Ubuntu. Unlike the question How can I use Chromecast, the issue doesn't seem to be firewall related. I have already tried opening the ports ...
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1answer
58 views

Help writing server script to ban IP's from a list

I have a VPS that I use as an openvpn and web server. For some reason, my apache log files are filled with thousands of these hack attempts: "POST /xmlrpc.php HTTP/1.0" 404 395 These attack attempts ...
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47 views

iptables rules keep showing up

I just installed an ubuntu precise server, after a few weird communications issues I checked the iptables list and found: Chain INPUT (policy DROP) target prot opt source ...
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18 views

Port Forwarding udp didn't work

the tcp forwarding work. My commands: sudo iptables -F sudo iptables -A FORWARD -j ACCEPT -p tcp --dport 3072 -d 10.42.0.84 -m state --state NEW sudo iptables -t nat -A PREROUTING -p tcp --dport ...
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2answers
75 views

Using Apache2 to set up a basic webpage

I am having a problem with a test page I set up for my website. The config file (index.html) looks like this <html> <head> <title>Welcome to website.net!</title> </head> ...
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33 views

How to make Charles proxy server accessible externally?

I'm trying to use http://www.charlesproxy.com/ to check what requests an iPhone app is sendins to a server. The concept is to set the proxy on the iPhone to Charles and start recording. The ...
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1answer
158 views

Can't ssh into server, connection refused

I can't ssh into my server. The server is on a private network administrated by me. Ubuntu is version 14.04. This started when I changed to a wired ethernet card. The client is MobaXTerm (latest) ...
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37 views

How to reset/flush remove ufw rules in recovery mode in ubuntu 12.04

Hello I think I have mistakenly locked myself from a remote server (ssh). I had a way to restart in recovery mode but it seems ufw is not even installed when in recovery mode. should I follow ...
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34 views

How to route between two separate internal networks

I've got two networks I'm trying to connect, both on different subnets. eth0 - 10.0.0.0/24 eth1 - 192.168.0.0/24 I've set up NAT for both on ppp0. Lets say Computer A (192.168.0.50) is trying to ...
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Port Forwarding

The IP of eth0 (where my "internet is"): 81.201.144.160 And I've got a Router at the computer (wlan0), where my mobile phone and xbox are connected. The IP is: 10.42.0.1 I need a TCP+USP Port ...
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57 views

Passing ICMP between two interfaces

I'm trying to setup routing between two network interfaces on an Ubuntu machine. The first interface is the nic, connected to my LAN. The second interface is a tunnel dev created by OpenVPN. The ...
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1answer
390 views

Iptables rules no longer honored

I installed Ubuntu Server 64-bit 14.04 a week ago. It worked fine for one to several days, then out of the blue, iptables became meaningless (I noticed FTP and such are down ). Only ports 22, 25 & ...
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37 views

VirtualBox, Ubuntu clients, internal network proxy to supply internet

Probably this question was asked many times, but I seem to be unable to find proper solution. Here is my setup: Two virtual machines(Ubuntu 12.04) M1 and M2. M1 has 2 network adapters: eth0 set ...
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2answers
64 views

What is MASQUERADE in the context of iptables?

In Iptables many times I see the target MASQUERADE. What is that. I searched and find lots of things. But I need some one explain me what MASQUERADE is in a so easy way? **If you bring an example ...
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1answer
60 views

Redirecting external ports to local ip

I have a ubuntu 13.10 server and a registered domain name. I have a web server on my 192.168.24.1 machine and a ftp server on my 192.168.24.2. Using iptables I want: 1) people who write : ...
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41 views

Ubuntu 13.10 allows connections from LAN but not from outside LAN

SSH ports configured to all 22 and another one. I can connect from another Linux/Windows workstations on my home LAN no problem. Same thing for nomachines nx server. Teamviewer connects with no ...
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236 views

Not pinging with host-name and can't ssh using hostname [duplicate]

I have setuped a DNS server in Centos6.5 and its working with every client machines other than ubuntu, now i have issue with ubuntu While im trying to ping from desktop machine to DNS server as ping ...
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3answers
1k views

Is someone trying to hack into my server? What can I do?

A few weeks ago I posted a question here about some ssh issues I was having with an Ubuntu 12.04 box. Fast forward to today and I am trying to allow someone else access to the machine, but they keep ...
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1answer
60 views

iptables command to give internet to my guest OS via virtual box

Based on this link there is a difference between Host-only network and NAT. So I want to set the LAN connection between my host -14.04 ubuntu- and my guest XP by Host-only network. How I can give ...
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1answer
207 views

Firewall rules for transmission

I have transmission installed, which listens on the default port 51413. I have tried opening everything for this port. iptables: Chain INPUT (policy ACCEPT) target prot opt source ...
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1answer
58 views

How to block ip forwarding for specific remote ip address

I use ubuntu as gateway for several hosts. I need advise how to block ip forwarding for specific ip address or specific ip range? I tried to block ip via ufw deny rules, but it looks like ip ...
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1answer
39 views

iptables ruleset blocking all network activity?

I've gone through numerous trial and error to recently discover that my iptables result is the culprit of blocking all LAN and WAN activity. I know this, because if I comment out the last line in my ...
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65 views

Port forwarding out multiple VLAN interfaces that have same IP address

So I have an Ubuntu machine with multiple VLAN on an interface eth1 and each VLAN has the same IP address (172.16.0.2). I need to be able to simultaneously telnet into a rack of devices that are also ...
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1answer
175 views

Where is /etc/sysconfig/iptables-config in 14.04

Where is /etc/sysconfig/iptables-config in 14.04 I can't comment in this thread because I do not have a reputation of 50 Configuration of iptables (verfication, actives services, allow FTP)
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73 views

Something is not quite right with these iptables' rules?

I found this after googling: iptables -A INPUT -i lo -j ACCEPT iptables -A OUTPUT -o lo -j ACCEPT #allow loopback access iptables -A OUTPUT -d 255.255.255.255 -j ACCEPT #make sure you can communicate ...
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1answer
260 views

Dnat prerouting does not work on Ubuntu 14.04

I've got a Ubuntu 14.04 server used as firewall, router, dhcp, dns and proxy. Everything works properly from inside to the internet, but the forwarding from outside to the inside network doesn't work. ...
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100 views

Ping to Honeyd virtual host replying Destination Host Unreachable

I have installed and am running honeyd and farpd successfully on Ubuntu 13.10. But, now the problem is: Pinging the virtual host from honeyd host (and from any other local network machine) #ping ...
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2answers
3k views

ubuntu 14.04 default firewall rules

I would like to know exactly which scripts are responsible for default iptables rules (no ufw, no gufw) in Ubuntu Server 14.04. After fresh installation even with ufw disabled (by default) there are ...