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

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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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150 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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254 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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539 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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23 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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447 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
68 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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250 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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82 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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794 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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59 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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103 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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128 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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120 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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45 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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104 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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74 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
1k 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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150 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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70 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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82 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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1k 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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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
156 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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186 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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62 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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1k 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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2k 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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71 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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690 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
85 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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52 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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141 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
619 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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102 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
661 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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156 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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6k 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 ...
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429 views

Squid as proxy is only allowing https traffic

I have installed Squid with Dansguardian and configured it exactly as instructed here. It works fine for https traffic, which is allowed through just fine. However, squid doesn't allow any http ...
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2answers
384 views

How do I with ufw deny all outgoing ports excepting the ones I need?

I did the following: ufw default deny outgoing, sudo ufw allow out 80 which I thought would let me use the Internet but didn't can y'all help? Also are there any other ports used by Ubuntu for which ...
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1answer
498 views

what does this mean “80/tcp filtered http”

Our linux server(ubuntu) stop listing on port 80. this is what i got : PORT STATE SERVICE 22/tcp open ssh 80/tcp filtered http what does this "80/tcp filtered http" means? What ...
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1k views

How to make modprobe ip_conntrack_ftp persist a reboot

Sorry if this is a stupid question, but to get outbound active FTP connections through our firewall we need to run the following: sudo modprobe ip_conntrack_ftp I learned this trick from ...
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1answer
55 views

Ubuntu forward ports, default state, forwarding not working?

im running ubuntu 12.04.4 server. I been googling the nett for answers, but could not find any.. I would like accsess a few web-gui's on my server. I have forwarder the ports in my router, worked when ...
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176 views

Use squid3 on same machine in tor browser 3.5

I'm using Tor Browser bundle 3.5.3 and squid3 (version 3.3.8) on Ubuntu 13.10 as transparent HTTP proxy on the same machine (i.e. not usual setup on gateway). I redirect HTTP request through squid ...
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1answer
2k views

redirect port 80 to 8080 and make it work on local machine

I redirected traffic for port 80 to 8080 on my machine with sudo iptables -A PREROUTING -t nat -p tcp --dport 80 -j REDIRECT --to-port 8080 It works fine for all world except my own machine. I am ...
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using iptables to restrict VPN user access to internal network

So say I have a set up in which a single server running virtual machines and a pptpd server. The pptpd server hands out IP addresses in the 192.168.0.0/24 range. The virtual machines have IP ...
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1answer
309 views

Iptables and bind9 to forward to google's dns

Hello i have a very hard time on getting along with iptables and bind9 as my internal network dns server. It's configured to forward my queries to google's dns (8.8.8.8). The main problem is i can't ...
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133 views

Ubuntu 12.04 secondary IP externally inaccesible

I have added a secondary IP to my virtual server, Ubuntu 12.04 running in OpenVZ virtual host. I used ip addr add xx.xxx.168.95/32 label venet0:1 dev venet0. When I do ifconfig the IP shows up below ...
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1answer
104 views

Outbound SMTP redirect

How would I go about redirecting all outbound email on port 25 of my server to port 25 on another server using iptables. I have tried a few rules already and none of them are working. Would ...
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1answer
960 views

Can curl localhost, but can't access port 80 from LAN

I can't find an answer to this question anywhere. I have ssh access set up, and can tunnel into my server. When on the server, I can curl localhost and get a response: curl localhost However, when ...