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

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Port Forwarding

I have a Linux Server CentOS 6.3 that has multiple network cards and 10 IP Public, and 10 NIC is connected to the internal network Now I want the each IP to be forwarded to a client in each network ...
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How do I set up a firewall/iptables using rc.firewall?

I am new to Ubuntu and am having a bit of trouble getting my firewall set up for my Network Security class. We are set up with 3 virtual machines - a Gateway, a Server, and a Client. We are supposed ...
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Ubuntu Server low client dowload speed

In the work we have a Ubuntu server 14.04 working as a proxy server, dhcp and Firewall, we assigns the clients Ips Manually in the dhcp for each Mac Address. The most of the clients go out through ...
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Drop packets by latency [on hold]

It's possible drop a udp packet by her latency (ping)? For exemple, i need drop packets with latency < 80ms It's possible? iptables? Ubuntu 10.04 x64
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26 views

The server cant resolve host names

Please help with the following problem. Server is running under Ubuntu 14.04 server 32x. IP tables: INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0] -A INPUT -p icmp -j ACCEPT ...
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Shows :::18332 instead of 0.0.0.0:8332, what means that?

What means ::: in front of a port (where usually the IP should be) when doing netstat? It shows :::18332 instead of 0.0.0.0:18332 and I can't connect to that port from the outside. This is for ...
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8 views

Iptables doesn't change the destination ip

I have a simple iptables rule: iptables -t nat -A PREROUTING -i eth2 -p tcp --dport 3389 -j DNAT --to 192.168.10.102 Note that my default gateway to internet is eth1 (eth2 is a secondary link). In ...
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41 views

Redirect iptables to apache without internet connection

I have set up a Personal hotspot using Hostapd. But this hotspot is not connected to the internet but I do have Apache installed on it. What I am trying to achieve is to redirect all the clients (that ...
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11 views

webstorm website connecting remotely

I am new to Ubuntu and to webstorm so please bare with me if its very basic question. I am trying to connect to the website run by webstorm on Ubuntu from Windows 8.1 PC ...
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How do I find which OS layer (iptables, rp_filter, etc) is dropping a packet?

Let's say that I'm running a ping towards a machine and I see from tcpdump that the icmp echo reply is being received at the ethernet port but the ping program is not getting it. So I know that ...
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34 views

Why can I not install iptables?

linux newbie seeks help please! I've set up a VPS as a mail server using dovecot and postfix and I'm trying to install iptables to secure the box a bit more however when I do I get the following ...
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35 views

How can I prevent being locked out after changing the iptables default policy?

I am working on a experiment when I (client) ssh a gateway and run sudo iptables --policy INPUT DROPthen the gateway doesn't accept any communucation(or input) from my client. By running sudo iptables ...
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37 views

How to route inbound traffic on one interface to another interface in the same machine?

I have searched the forums, but can't find a solution that addresses my use-case exactly. I need to do this on a remote machine and so don't have a lot of latitude to get this wrong (and possibly lock ...
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1answer
234 views

Using Ubuntu 14.04 as router with iptables, clients can't go online. Probably DNS issue, iptables setting needed

CORRECTION 3: SOLVED! I needed to add the the official DNS server of my departement's VLAN as DNS to the clients. I've read through a large number of posts about iptables issues when using Linux as ...
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1answer
25 views

network bridge not forwarding traffic from span port on router

I want to run several security network tools in LXC containers like ntopng, suricata, snort, etc. I hooked one of my server's NIC's up to a port that is spanned to my firewall... so basically this ...
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16 views

NATing ports selection using hardware detection

I have a linux box to be used as a router with a wlan port in AP mode. The internet input to the board may come from either an eth port (WAN mode) or another wlan port. There is also VPN running that ...
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17 views

Use Ubuntu as internet gateway

I do have the following setup and would like my ubuntu pc to work as the gateway to the internet: Access point: 192.168.2.1 Ubuntu (wlan0): 192.168.2.2 Various other clients: 192.168.2.x Now, ...
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25 views

Failover/ gateway issue. Help please

hope someone can help, this would be excellent. I’ve ubuntu DHCP server (10.04), which works great (many thanks to everyone who helped me in this excellent forum). This server has 2 cards, eth0 for ...
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214 views

Open port 8080 on 14.04

I need to insert into iptables to open 8080. With the iptables I looked at iptables -L it is so complicated and has many division I am not sure where to put the rule to open the port. Here is my ...
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iptables debugging on ubuntu 12.04

ufw was blocking the incoming ssh connection. So removed and purged the ufw still the incoming ssh connection is blocked. But there is not logs in dmesg output. I am sure sshd is running, tested ...
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83 views

what could be blocking port 5060 on my ubuntu 14.04?

I have a ubuntu 14.10, and am trying to telnet into it via port 5060 but I keep failing. I always get the message "Connection closed by foreign host". I checked my iptable, it is default policy to ...
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92 views

captive portal and squid3 transparent mode

http://aryo.info/labs/captive-portal-using-php-and-iptables.html I did at practice. but squid (transparent mode should be) entered in the access.log s pages can not see. I use the following iptables ...
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46 views

How do I delete all iptables rules that match a filter?

I'm making a captive portal. The default ruleset is created as follows: # Flush existing rules iptables -F iptables -X iptables -t nat -F iptables -t nat -X iptables -t mangle -F iptables -t mangle ...
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56 views

ipset with iptables-persistent

iptables-persistent was not reloading my rules at restart, and I realized the problem was that /etc/iptables/rules.v4 contained a --match-set referring to a set of rules created by ipset - which had ...
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41 views

The program 'iptables' is currently not installed

I am a newbie, so my apologies up front. I am trying to get DansGuardian installed (which I believe I have) and working. To get it working I need to filter IP traffic through the app via iptables. ...
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43 views

Ncsa_auth squid on Ubuntu installation authentication

I installed squid on Ubuntu Server 12.04. worked smoothly. After Transparet mode to run iptables-t nat-A POSTROUTING-s 192.168.2.0/24-o eth0-j MASQUERADE I have run. and I got out to the internet. ...
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Restricting pptpd to certain websites

I've got basic VPN running on Ubuntu 14.04 (pptpd). I would like to restrict access when using this VPN to specific websites (meaning all other websites or ip's that aren't specifically mentioned ...
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43 views

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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28 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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41 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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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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359 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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55 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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55 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
62 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
43 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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95 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
100 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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182 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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346 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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22 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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303 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
58 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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206 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
57 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
599 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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44 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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91 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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110 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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103 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 ...