A firewall is a program that controls the incoming and outgoing network traffic on a system. Use this tag for all questions related to firewall configuration and operation.

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Disable networking only inside of a single terminal

I want to run a command in the terminal to disable networking, just in that terminal. How can that be accomplished? I'm running OSX. Note: I only want to disable the networking in that terminal. ...
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127 views

iptables: using “conntrack” and “recent” modules to block unsolicited packets

When I only allow RELATED and ESTABLISHED packets, and DROP everything else, my firewall rules work perfectly and I have no problems: ### VARIANT A -A INPUT -i wlan0 -m conntrack --ctstate ...
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588 views

OpenVPN and routing problem on OpenWRT

My home topology: router1 (192.168.1.1) - D-Link dsl2540u server with static IP available from Internet (ADSL via ppoe). 4 LAN ports. router2 (192.168.1.2) - D-Link DIR-300 with OpenWRT. Plays ...
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138 views

Why doesn't ufw enforce firewall rules for traffic coming from Virtualbox VM

I've been running Linux Mint 17 on my laptop for a while and thought I had it locked down to not allow any incoming traffic through "Firewall Configuration" (ufw GUI)—I have also validated this from ...
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47 views

Why is traffic matching the public zone instead of the desired zone?

Trying to self-train on firewalld I set up apache and configured the zones as follows: [root@localhost ~]# firewall-cmd --get-active-zones work sources: 192.168.122.1 public interfaces: ens3 ...
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98 views

Defining IPv6 chains in ip6tables-restore/iptables-restore files, is it possible?

The format for the files generated by iptables-save/ip6tables-save and loadable through iptables-restore/ip6tables-restore stipulates that one can prepend -4 or -6 respectively so as to maintain the ...
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661 views

Corosync & Pacemaker IPTables Rules

When using Corosync with two rings via multi-cast addresses 226.94.1.1 (Port 5405) & 226.94.1.2 (Port 5406) what iptables rules are required to allow two nodes to communicate optimally without ...
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160 views

FreeBSD pf firewall, new connections severly delayed when nating

I have a newly setup fbsd 9.1 with pf, which itself doesn't experience any slowness when for example downloading a debian iso from my local debian repo (ftp.se.debian.org). Any machine behind it, ...
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911 views

openwrt firewall - block a set of ip addresses from internet access

I'm running OpenWRT Attitude Adjustment r33556 / LuCI Trunk (trunk+svn9325) on my WNDR3800. I would like to configure my firewall to: Only allow a specific range of IP addresses to access internet, ...
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276 views

Port Forwarding Between 2 Internet Machines

Here's my scenario: Setup There are 3 machines: A: on the internet : has ip (a.a.a.a), has port pa open B: my server / gateway : has ip (b.b.b.b), has port pb open C: on the internet : has ip ...
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918 views

pfsense long ping to google

I have a pfsense box set up. What happens is I set a rule so I can't hit the admin interface 192.168.3.1 from the box. With the rule enabled --- www.l.google.com ping statistics --- 2 packets ...
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12 views

equivalent of iptables rule in ip6tables

I m newbie in the iptables. I have the following iptables rules in the source code of a project iptables -t mangle -I PREROUTING ! -i br0 -p TCP --dport 45 -j MARK --set-mark 0x1000 iptables -t nat ...
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54 views

How to create a rule on IPCop firewall for bittorrent trafic to work properly?

I've been trying to use my favourite torrent client (µTorrent) after setting up my IPCop (last update 2.1.9) and it warned me that my router/firewall was blocking the traffic and that I had to open a ...
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35 views

CSF not blocking port when removed from csf.conf

I have removed VNC port 5901 from the csf.conf configuration file and executed a csf -f a csf -x and a csf -e to flush and restart CSF. There is a vncserver running on port 5901 and when doing an ...
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22 views

Shorewall configuration : providers and LAN

Hi all and thanks in advance for the answers. Currently, I have different providers configured in shorewall. I'll will probably have to change one of them. The problem is I won't have any Public IP ...
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45 views

How do you tweak iptables limit rules on openSUSE Tumbleweed?

I have a fresh install of openSUSE Tumbleweed, it is logging a lot firewall related stuff due to my apple devices multicasting to enable airplay. Lines look like: Mar 14 12:45:13 server kernel: ...
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36 views

ufw firewall - how to only “allow” when I am going through a proxy

I am using a proxy to navigate on internet, and I am trying to setup a firewall that will only let me connect to internet via this proxy: if I forgot to turn on the proxy, that I should not be able ...
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87 views

OpenWRT on embedded device as firewall

I have the following setup in my network: My internet comes in through an ATT Uverse modem/router. The router is in bridge mode because that ATT Uverse modem/router connects to a second higher ...
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54 views

Redirect all ARP traffic from eth0 to eth1

I would like to redirect ARP traffic, but I'm struggling with arptables and ebtables. I have 2 interfaces: eth0 10.10.10.25 eth1 10.10.10.20 Both in 10.10.10.0/24 I want to redirect the ARP ...
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115 views

How to setup reverse FTP in RHEL?

Researched: http://www.thecave.info/export-proxy-username-password-linux/ http://stackoverflow.com/questions/5334110/text-based-ftp-client-settings-behind-a-proxy ...
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67 views

firewall-cmd forward rules for interface with multiple ips

I'm looking for a way with firewall-cmd or another command to do the following. An incoming public interface has multiple ip addresses bound to it. How can I forward ports only for one of the ip ...
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89 views

Linux Bridge Network with Static IP Addresses and Firewall

any and all help is appreciated. I am trying to set up my Network Map Can you give me advice in setting up my interface file? If I set a static IP on my PLC on the same gateway, I shouldn't need to ...
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39 views

Initial iptable rule and knockd operation in vps

Today I launched a vps with Debian 7 x64 and started playing around with it. I installed xampp as well as knock daemon to get my hands dirty. So, all I wanted to do was to actually block all requests ...
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143 views

iptables: can't open tcp port

I'm running a Raspberry PI B+: Linux pi 3.12.28+ #709 PREEMPT Mon Sep 8 15:28:00 BST 2014 armv6l GNU/Linux The Raspberry is connect via lan (dhcp. ip: 192.168.78.29) to the local network. I'm trying ...
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124 views

Iptables and --tcp-flags

If I have the following rule in the nat-table in the prerouting chain: 0 0 REDIRECT tcp -- eth5 any anywhere anywhere tcp flags:FIN,SYN,RST,ACK/SYN redir ports ...
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246 views

Configure firewalld for OpenVPN (server-bridge) in Fedora 20

I've installed an OpenVPN server on Fedora 20 (server-bridge), but I cannot get it to work. I'm almost sure that It's a firewall issue. I'm trying to connect from an OSX client, but I can connect ...
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4k views

Redhat / Centos 7 Firewalld best practice for pptp or L2TP/IPsec rules

Having a quick look at Centos 7, and though I'd spin up a VPN daemon or 3, but immediately discovered the usual packages aren't yet in the core repositories, so had to dig around and found the ...
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68 views

How to debug the network issue in case of blocked database connections

I am trying to understand if my analysis of the below information is correct. For all the 3 scenarios listed here, port 80, port 3306 and port 22 are open in the server's firewall. Also, for all the 3 ...
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122 views

How do I control ip routing in the new firewalld?

I have the following scenario: Our fedora server is connected to the internet on eth0 and has a second nic, wlan0 acting as an access point. The purpose of the access point is to provide a connection ...
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255 views

iptables server behind NAT accessible from outside as well as inside the nat

I have 2 machines with a KVM running on each machine - so two kvms with the below networking Host 1: 192.168.10.100 (eth2) 10.10.100.1 (virbr1) KVM 1 (NAT with Host 1): 10.10.100.128 (eth0 ...
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120 views

Linux firewall distro that can configure a vpn connection as a WAN interface?

I'd like to setup linux as a router w/firewall between My machine and the internet. The linux box should connect to a VPN account using OpenVPN on boot (managed to get that done). Then the firewall ...
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173 views

pfsense: No more processes

Sometimes my pfsense (1.2.3-RELEASE) goes crazy: every nat rules go down the web interface reply me with many errors (Warning: shell_exec(): Unable to execute...) my ssh daemon refuse to open a new ...
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602 views

iptables and physdev match confusion

I'd like to be able to prevent a network bridge from generating certain types of traffic from some of its interfaces. If I understand iptables correctly, packets generate by a device appear on the ...
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194 views

cntlm: the request was denied

I have configured CNTLM server between users and Windows TMG firewall. CNTLM configured with "allow all" - no any ACL or something like it: Gateway yes # # Useful in Gateway mode to allow/restrict ...
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45 views

How to send packets coming from a second router on a particular port back to the router, using iptables not a route

I have a Linux server which runs a particular service listening on a single TCP port. The Linux server connects to the internet using a PPP connection and also acts as router for a local network using ...
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63 views

Shorewall “ERROR: Ordinary users may not start the /etc/shorewall configuration” in Cygwin

I am using Cygwin on Windows 7 and I have installed Shorewall 4.5.21.5. When I try to start shorewall in Cygwin, it gives me error: $ shorewall start ERROR: Ordinary users may not start the ...
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329 views

destination IP mangle table

I have machine with 2 interfaces: eth1 connected to internet (ip xx.xx.xx.xx) eth0 connected to my laptop (ip yy.yy.yy.yy) I add those lines to the firewall file in order to manage the bandwidth ...
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173 views

Firewall config prevents hibernate connecting to postgres in CentOS6.3

I have an operating environment in CentOS 6.3 that has tomcat7 and postgres9.2 installed. There is just one web application deployed in tomcat that tries to establish a connection from localhost to ...
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196 views

Full network logging via linux firewall ( iptables )?

How truly enable full network logging via iptables? There is an option --log-prefix to add a tag to log entries. But the log entries don't show all complete packets. What a grand way to enable full ...
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94 views

how to list blocked connections events by the firewall?

So, I used firestarter that had logged blocked connections events with some useful details (but it is not being updated and I found somewhat unsafe as any moment we could click to deactivate the ...
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120 views

Firewalld SELinux

Is there any way to better explanation firewall-cmd than the one given in Fedora18 wiki. I am trying to convert iptables to FirewallD in cmd line without GUI but cannot find a decent example or ...
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149 views

Perform Cisco's DNS Doctoring on FreeBSD

How to perform a change in the DNS response from a DNS server to be a different IP address than the DNS server actually answered for a given name? ...
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158 views

What other rules should I use to allow PPTP outbound connection?

I already allowed outbound connection to TCP/UDP port number 1723, but PPTP connection still fail to establish, If I allow all outbound connection, the tunnel will just go fine.
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16 views

firewalld isn't blocking/dropping ports for ports mapped from docker containers

I have firewalld installed and running on my machine. here are my active zones # firewall-cmd --list-all-zones ... drop (active) interfaces: enp2s0 sources: services: http https ssh ports: ...
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26 views

Forcing google/youtube safesearch on Ipfire

I use IPFIRE firewall os and even though it has a force safe search feature it doesn't seem to work. Would there be any other way to force this feature as I cannot seem to. Create a new cname in ...
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117 views

How can I redirect internet traffic from local to proxy server with ip tables (DEBIAN 6)

So i made topology as shown in figure. Router have 3 interfaces like this: eth0 to internet side (with ip 192.168.1.10/24 gateway 192.168.1.254/24). eth1 to server-PC side (with ip ...
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101 views

CentOS as home network router: IPTables Port Forwarding failure

I have currently set up a home server with a CentOS 6.6 installation on it. The server has two NIC interfaces which I'm using it as my router and DHCP server. Here's a diagram showing the network ...
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76 views

Opening a TCP port in Linux

I am trying to establish a TCP socket between my linux server and my client running on my laptop. The TCP server code I am running is, from socket import * HOST = '' PORT = 1999 ...
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26 views

how do I disable the firewall through YaST?

The fine manual states: The Start-Up section defines how your firewall will start. You can either have the firewall start automatically when booting (recommended), or you can set the firewall ...
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89 views

can't connect to remote host with MySQL…firewall problem?

I've granted privileges to thufir for remote access through the shell (correct?), but cannot seem to actually connect. The router firewall has SPI to off. I've disable the IPv6 firewall on the ...