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

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Confiruration DNAT in iptables

I have 2 PC be created by VMWARE 1. PC1 (make iptables router): ens33 's IP: 192.168.1.5/24 (network connection is bridged) ens37 's IP: 192.168.2.2/24. (network connection is wmnet9) 2. PC2 ...
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IPtables Config to Passthrough Internet 16.04

I am struggling to finish the config on my Ubuntu 16.04 fileserver to pass on the internet connection to my HTPC. See the network layout below: [Internet] <--> [DHCP Router] <--> ...
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Ubuntu 16.04 Tor Transparent Proxy

I want to setup an Ubuntu Server 16.04 to act as a transparent proxy for all traffic from a specific subnet to Tor. To be specific, I want all traffic on a subnet 10.20.0.0/16 when using the Ubuntu ...
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Zenmap Showing Filtered for iptables REJECT Rule

I've been recently messing around on my VMWare Ubuntu 15.10, and decided to test out my iptables and see if my Zenmap on my Windows host machine would recognize the ports being blocked. However, when ...
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26 views

How do I permanently removing a ban stored by Fail2Ban

I have two filters that have banned local addresses. I have added the addresses to ignoreip but the damage was done already and the bans are in place. Every time I reboot my computer I have to do an ...
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1answer
54 views

UFW not working in 16.04 server. Refers to earlier kernel module?

I am trying to move our mail server based on 12.04 to a brand new installation of 16.04 server. When I run sudo ufw status, I get: ERROR: problem running iptables: modprobe: ERROR: ...
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14 views

Deny guest user access to the Internet except to one address

I guess that an AppArmor profile has to be edited to archive that, but I'm lost on how to do it. If it is possible through an ufw or iptables rule I would be happy as well. Don't forget that it's ...
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33 views

Issues With Iptables

I have problems while performing iptables operations. modprobe: ERROR: ../libkmod/libkmod.c:556 kmod_search_moddep() could not open moddep file '/lib/modules/3.13.0-85-generic/modules.dep.bin' ...
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13 views

What is the UH flag in routing table

I'm using an Ubuntu machine as a server and it has two network interfaces. One is the 10.10.10.0/ 24 range and the other is 192.168.0.0 /24 range. I was trying to bridge these network interfaces as ...
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19 views

OpenVPN Ubuntu Server Routing Problems No Internet

I'm running OpenVPN on Ubuntu 15.04. When I connect to the server, I can connect and authenticate correctly (I use PAM auth because I'm lazy). Once connected I can't ping the server or access the ...
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30 views

Understand the differences between two network configurations for MAAS

I am trying to understand the differences between two network configurations for MAAS. My understanding is that the both achieve the same tasks where the first network connects to the internet and the ...
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23 views

Block port on one network address

I'd like to block a series of ports (mailserver) for all the network addresses on my server except one. I've got a server running Ubuntu 14.04.4 and configured with 2 ipv4 addresses per Linode's ...
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9 views

Port Access through VPN

I'm trying to access a PC from behind a VPN (PIA) using the Network Mgr on Ubuntu 14.04.4 but having some issues. Without the VPN up, I can access WANIP:8022 which port forwards to 192.168.1.10:22, ...
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1answer
21 views

iptables is blocking only some connections to port 80

I'm running a Ubuntu 15.10 server with an nginx webserver on it. I've used the following iptables configuration to allow port 80 and port 443 connections: *filter # Allow all loopback (lo0) traffic ...
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3answers
40 views

Adding VPN to firewall UFW

I'm having trouble at work in connecting to the work VPN while Firewall (UFW) is active. When i disable it "sudo ufw disable", there are no problems. When it's on, when trying to connect I receive ...
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21 views

open wifi Captive portal w/only local net (no internet/wan)?

I am trying to set up a wireless 'test' box to use on a private club (11,000 acres). The initial tests won't need anything fancy, it will just be checking the visibility of a hotspot from a high-point ...
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1answer
17 views

iptables-persistent / netfilter-persistent has (dependancy?) problem on 15.1

I'm trying to install 15.1 x64 on a new VPS. The first thing I do is ssh in and define a few iptables rules to drop non-ssh traffic, and now want to make those rules persistent. So: root@server:~# ...
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30 views

Easiest way to forward a port on local network

I have a server (python -m http.server) running on hostA:8000. Say I want to forward traffic from hostB:8004 to hostA:8000 How can I achieve that from hostB? I've already tried, $ sudo ufw allow ...
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24 views

Using UFW with ipsets

I am running Ubuntu 14.04 on a VPS for business purposes. The firewall is setup using ufw; testing reveals that it's working well. I'd like to further secure my server using techniques described ...
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19 views

Allow winscp/filezilla through iptables and fail2ban

I just launched a website within my school community and woke up this morning to logs of someone trying to bruteforce into my server. I followed some guides on digitalocean to set up fail2ban and ...
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21 views

Ubuntu is not accessible from LAN when ppp0 is up

I have successfully connected my Ubuntu server to a VPN server. Unfortunately, it is no longer accessible from inside of my LAN unless I kill the VPN connection. I use PPTP. What if I want a specific ...
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1answer
38 views

External access to Ubuntu single-node openstack horizon dashboard

I successfully installed openstack on spare server using the ubuntu single-node installer script. The openstack status page on the underlying ubuntu instance is green across the board. From the host ...
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49 views

Inherited Ubuntu server will not PING: What am I missing?

Update: It turns out, our in-house network suppresses pings. I demonstrated this by turning my phone into a hot-spot (thus changing my outbound gateway), connecting with a laptop, then pinging the ...
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38 views

Setting up NAT forwarding using iptables on ubuntu server 14.04

I have a server with 2 ethernet interfaces(em1 and em2). em1 is the internet facing interface(192.168.16.113) and em2 has a static address(10.1.1.100) connected to a switch. I have configured the ...
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10 views

How to route external traffic via mobile-phone usb modem and use ethernet for internal traffic?

Suppose my internal traffic all goes through some ip like 10.0.0.1 for example. I want to tether internet connection from my mobile phone to my desktop while still have the access to internal network. ...
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27 views

VPN doesnt ping the local network

I am using OpenVPN for connecting to office network. I have a VPN client configured on the laptop in my home Internet connection. The objective is to get connected to a VOICE SERVER sitting in the ...
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30 views

15.10 “falls off network” but all services are still up

A problem has been plaguing my Ubuntu 15.10 4.2.0-34-generic i686 VPS for a couple of weeks now. There will be a small (2-3Mb/s) spike in outgoing network traffic, and then the VPS will cease to ...
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49 views

IPTABLES Block FXP download from a IP

I am trying to block an FXP upload from a specific IP eg. 188.145.11.10. The problem is that I want to allow a download to 188.145.11.10 but I want to BLOCK the upload from that IP. For example: ...
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19 views

How to perform NAT with inside interface as bridge

I have a following network diagram: network diagram 192.168.0.0/24 network with 4 web servers (.1,.2,.3,.4). There are 2 Ubuntu 14.04 (VM1 and VM2) in it. They have 2 physical interfaces both (eth0 ...
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62 views

iptables and hacker prevention

Hello fellow Ubuntuers! here is an example of my iptables.rules file: *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] :f2b-sshd - [0:0] :f2b-sshd-ddos - [0:0] -A INPUT -p tcp ...
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46 views

fail2ban won't work

A few days ago I setup a new whole Server (Mailserver with Zarafa / Postfix, Apache, MySQL, and so on). Everything works fine.. except fail2ban. Fail2ban do nothing. He don't even act if something is ...
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232 views

Can't initialize iptables table `filter': Table does not exist (do you need to insmod?)

I'm trying to open up port 1900 for UDP in order for the Echo to be able to discover the HA Bridge using the following command but I get errors. What is the best solution to fix this? ...
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33 views

Server iptables configuration

I have an application installed in the /usr/local/tomcat/fakebook directory. I want to allow any user to use the app and also all external user to use the app. I just want to allow connections to the ...
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19 views

Merging IPTABLES

In advance, thanks for all help! Hi. Got two ubuntu servers running fail2ban. I am currently trying to write a bash shell code to sync the iptables and / banned ips. So I got this rules from ...
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78 views

iptables port redirect in nat table but traffic still showing up in the filter table?

I asked a more specific question over on stack overflow a few days ago, but thought I would try and generalise it a bit here... In the nat table, does doing a port redirect in the prerouting chain ...
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27 views

DNAT redirecting to specifc port is not working

I want to redirect ssh by port using DNAT, and i do try to ssh it through the command > username@IP_ADDRESS:10003 and i got this message "ssh: Could not resolve hostname IP_ADDRESS:10003: Name or ...
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37 views

Still seeing connections from IP after blocking in fw

So I'm using iftop to monitor connections on my server, and I'm seeing this ip address 116.110.127.24 making constant connections on ssh port. (I'm not sure if this means 22 or my actual ssh port, it ...
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1answer
32 views

how can i kill all established connections before running iptables bash scrip

there is established connection from before running iptables bash script, and even this connection is blocked by iptables, but it keeps running because it is in established status, which according to ...
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33 views

meaning of -m in iptables

I use the following commands to turn my laptop into a router, that routes traffic from eth0 to wlan0 and vice versa. $ echo 1 > /proc/sys/net/ipv4/ip_forward $ sudo iptables -t nat -A ...
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1answer
158 views

Docker Transparent Squid Proxy

I am trying to run a squid3 transparent proxy in a docker image, on my laptop. Then on the same laptop I want to use the transparent proxy. The reason for the proxy is to abstract a corporate proxy ...
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51 views

Ubuntu as router; redirect traffic from 1 client (LAN) to VPN

I have a Ubuntu 14.04.03 router (iptables). Behind it there is a LAN with laptops, tablets, smart TVs, etc. I would like to use VPN on my TV, but there is no such option in the TVs software/firmware. ...
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25 views

the packet flow from a network interface to a local process? help!

I'm read Linux Iptables Pocket Reference. So I do not understand the figures presented. It says that packets travel through chains, and are presented to the rules one at a time and in order. Then ...
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Forwarding traffic with IPtables through a series of IDS

My goal is to run several Intrusion Detection Systems (IDS), these IDS sensors should be positioned in sequence, so the traffic will travel through the first IDS and will generate alerts of malicious ...
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1answer
55 views

Multiple connections per ip

I am running Ubuntu with a webserver (Nginx). I noticed that one IP has multiple connections opened. My server works all fine and there is no issue. I am just curious to know why there are many ...
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94 views

IPTables forward port to another ip:port but keeping original source ip

I have following iptables rules on gateway machine(192.168.0.1). I want to forward port 192.168.0.1:80 to 192.168.0.2:8080. But I need to maintain original source ip so that original server can get ...
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35 views

TCP IPTables Expert ubuntu 14.04

I started hosting my game-server on Ubuntu Linux 14.04 I am having an issues ، some enemies/bug abusers log in 2+ characters in the same second then they spam a certain spell/word that lags/stops my ...
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105 views

IPtables ubuntu 14.04 LTS

I am new to Linux, I used to use windows for years and this is my first time to use Linux "Ubuntu 14.04 LTS" I am hosting a game-server I was wondering if it is possible to make IPtables to kick if ...
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32 views

Connect two subnets so that they can see each other

I've got 3 machines (virtual) : A client, a server, and a destination. (All running ubuntu 14.04). The client and server are interconnected via a subnet, and have the ips 10.10.100.4 and 10.10.100.2 ...
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35 views

libiptc error on unbunt14.04

Am trying to work with iptables, using libiptc to manipulate the entries. Header looks something like this. I have iptables-dev installed on my machine. Am getting following error, but the same ...
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36 views

Forwarding UDP data between two local interfaces

I have server which has 4 eth ports: - eth0: 192.168.226.55 (Internet connection, default one default route) - eth1: 10.8.8.1 (local network) - eth2: 192.168.225.129 (Internet connection) - eth3: ...