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

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After setting up pre/post-routing, why is my port forwarding still now working?

I am set up with 3 virtual machines - a gateway, server, and client. We are tasked with setting up iptables on the Gateway to forward HTTP, SSH, and FTP traffic from the Client to the Gateway to the ...
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11 views

3.13.0-37-generic basic router repeatable issue - packet loss

I have two desktop PCs and I wish to use them as a simple router between two LAN segments. I am not using NAT, SNAT, DNAT, and all my iptables tables/chains policy are ACCEPT. With iptables wide open ...
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34 views

Iptables troubles

I used webwin for iptables management and reset the firewall over webmin (to clear out all the old stuff). I also disabled the feature Activate at book. After that I installed iptables-persistent for ...
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10 views

Make Proxy Server with arno-iptables-firewall

I am trying to configure arno-iptables-firewall to work with transparent squid but no success. browsing is ok using local configured proxy on the computer but can make the arno-iptables-firewall to ...
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28 views

Port redirection for a specific (dynamic) IP using iptables script

What I want: Incoming TCP and UDP connections on port 900 from the resolving IP address of myip.dyndns.org (dynamic IP) should redirect to port 5050 on the local machine. All other IP addresses ...
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5 views

iptables like leflexive

is there any options to implement like leflexive acl (They are generally used to allow outbound traffic and to limit inbound traffic in response to sessions that originate inside the router. ) ?
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7 views

Iptables like reflexive acl

Is there any iptables implementation like reflexive acl ? and how do you provide your security using iptables
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14 views

What is UFW's approach towards rules order for overlapping rules?

I need to enable UFW in my Ubuntu 14.04 Server having these conditions: - I want to deny all incoming and outgoing on all ports (and protocols) but: - I want to allow all incoming and outgoing on a ...
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27 views

iptables : ssh output redirection

I'm trying to configure iptables to redirect ssh output, but to test I first configure tcp redirection like this: protocol : tcp source IP : 127.0.0.1 source port : 69 destination ip : anywhere ...
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40 views

problem with Openvpn on openVZ VPS

Ok guys. I finally joined this forum after lond educational journey of linux :) I'm advocate of making research on my own before asking questions. But after several days of trying to figure this out I ...
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43 views

Routing with virtual interfaces

How do I setup Ubuntu Server (14.04.01) with public eth0 and private eth1 to act as a router for multiple public/private IP pairs. eth0: 200.0.0.2 eth0:1: 200.0.0.3 eth1: 192.168.0.1 ...
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28 views

How do I bridge the eth0 (ethernet) and eth1 (WiFi_Ap)?

I am in the WiFi test embedded board. The ethernet port eth0 is connected to the Internet. The interface eth1 is caused due to the WiFi chip. The Access Point can be used as a WiFi eth1 is. We use ...
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1answer
20 views

How do I remove all the ufw chains from iptables?

I've removed ufw and I want to get rid of all the chains it leaves behind. How can I do that easily?
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10 views

Writing exceptions in ufw to the default forwarding policy

I've tried setting DEFAULT_FORWARD_POLICY in /etc/default/ufw to both REJECT and ACCEPT and then writing rules to create exceptions to the default forward policy. No matter what I do, it appears to ...
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1answer
61 views

Setup NAT on Ubuntu 14.04

I'm trying to insert my desktop between an appliance and the rest of the network to monitor the traffic coming off of it due to some security concerns. I'd like to setup NAT so that the devices behind ...
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1answer
50 views

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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18 views

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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1answer
34 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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34 views

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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15 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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1answer
58 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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13 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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24 views

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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64 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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2answers
42 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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1answer
49 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
653 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
41 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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18 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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23 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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1answer
32 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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473 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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139 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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122 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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75 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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87 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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63 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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62 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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12 views

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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55 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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33 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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56 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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62 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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568 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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100 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
85 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
99 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
48 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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113 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 ...