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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Using IPTables to Block Ports to Class A Subnets While Allowing Web Ports (80/443)

This is about a cPanel server which, like most servers, is under constant attack from lands afar. Considering that I only host to clients in the US and Canada, there is less of a reason to allow full ...
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How to stop outbound ftp from being established. centos/ rhel

What is the method to block a machine from establishing connection to an outside ftp server. Both ftp and sftp. inet, iptables, shutdown service?
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Unlocking all ports in a router when using Linux

I heard that Linux's open ports are not very vulnerable, so a normal desktop Linux installation doesn't need a firewall. Still, my router (Dlink) blocks some ports, even in LAN. Would it be a bad ...
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Advanced Policy Firewall: allow_hosts.rules doesn't work

I'm trying to open ports for Nimsoft. In allow_hosts.rules I opened ports for private network: tcp:in:d=48000_48020:s=10.0.0.0/8 tcp:out:d=48000_48020:d=10.0.0.0/8 During starting apf I see that ...
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Linux VM as a firewall

I have 3 vms a->b->c. I want to setup b as a firewall. Traffic is routed from a to c through b and I put a file on c. How do I show that b works as a firewall (first show that you are able to transfer ...
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Port is open but I can't ssh to it

My company PC is behind the firewall, I want to connect to my remote server. The port is open however I can not connect to it, does anyone know the root cause? From my company PC connect to my ...
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Change timeout of an entry of ipset with iptables rule

I'm trying to create a set with ipset and using it in some iptables rules. ipset has timeout option to set a countdown timeout to an entry of a set to automatically remove it after a period of time. ...
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How to let the Firewall of RHEL7 the SNMP connection passing?

How to let the Firewall of RHEL7 the SNMP connection passing? When I did this command on the computer: systemctl stop firewalld All the SNMP packet are passing well. When I restarted firewalld ...
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Working with firewall-protected server through ssh (dynamic IP)

I need to work on a Debian 6 server through SSH. The server is firewall-protected and SSH connections are filtered based on the user IP. Unfortunately I have an ISP provider with dynamic IP - it's ...
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Is there any way to configure fully automated proxyclient for workstations?

My network diagram is similar to above image; pc-router is also acting as firewall & I'm running squid on it. pc-router is running debian Vlan having workstations running fedora, ubuntu and ...
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iptables to block all websites

I have Debian 7, and I want to block all websites in my computer, unless my email, using IPTABLES or others firewall. How can I block all website, include http and https too. How can I do this?
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Which ports should I open for apt-get to work?

I installed Webmin, and then set up the firewall like this: INPUT SSH port ALLOWED Webmin port ALLOWED HTTP port (80) ALLOWED DROP EVERYTHING ELSE FORWARDING no rules OUTPUT no rules If I remove ...
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Error when redirecting ports with iptables: No chain/target/match by that name

I am trying to redirect all incoming TCP connections, originally to port 80, to port 8090, because I am running Confluence in 8090 and I want to avoid it running as root, which is a requirement to ...
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28 views

ufw rule deny default outgoing

I want to deny all outgoing traffic by default, except ssh connections. I added this rules: ufw default deny outgoing ufw allow ssh Then I restarted the firewall by: ufw disable ufw enable ...
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Block outgoing connection from running process

I have an java application that I have been developing. I use a external db server that I can't control. I want to simulate connection error to it, but I'm unable to do it. I have tried to use ...
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69 views

How to Mark Traffic using IPtables?

I'm trying to mark traffic, How shall I write following code in terms of IPtables? /ip firewall mangle> add chain=prerouting src-address=10.1.1.1/32 action=mark-connection \ ...
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59 views

Block outgoing connections to certain IP using PF

Can someone give me a hint on how to setup a basic deny rule whenever any TCP request is sent to a specific IP address? I am using the PF packet filter. Any help?
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How to block telnet using iptables command

I am trying to block telnet on my server but I have failed to do so. I have added following firewall rules in INPUT chain of filter table for the same. INPUT CHAIN(filter table): <some other ...
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2answers
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iptables configuration - ssh connection only from a remote network

I'm trying to configure Iptables of a server in order to permit SSH incoming connections only from a certain network. by the way this is the rule chain : # Drop anything we aren't explicitly ...
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Why is my laptop being blocked from connecting to a PPTP VPN server?

I have a fairly simple network at home Internet --> Modem --> Linux Router --> Switch --> Laptop The problem: There is a PPTP VPN server at work that I need to connect to from home. I configured my ...
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Blocking or forwarding packets as access point

I set up my Pi 2 as a wifi access point following this tutorial. I'd like to implement a rudimentary QoS, according to the DSCP field in every packet's header. That means, blocking packets using low ...
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58 views

to allow certain ips and block all other connections on AMAZON EC2 ubuntu 12.04

How do I allow certain IPs and block all other connection in iptables on AMAZON EC2?
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is iptables broken on my raspberry-pi? how to fix?

I am getting some person(s) trying to brute force my ssh, from multiple ip addresses (small sample) : May 22 19:50:02 rpi sshd[1272]: pam_unix(sshd:auth): authentication failure; logname= uid=0 ...
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How can I allow SSH and SMTP only using IPTables?

I've got a raspberry pi set up to send me periodic emails. As it's connected to the internet 24/7, I need IPTables set up properly. I want to allow incoming SSH and allow emails to send out on port ...
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Help about CentOS 7 apps & Driver [closed]

I'm using pc for several years but never tried Linux so I'm quite noob in this field. I'm using Autodesk maya, Nuke & will learn houdini very soon. I found that linux works faster for this apps so ...
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Linux IPTables - Ignore Range of IPAddresses

I am currently modifying some of my IPtables rules on a public server and have run into a bit of a dilemma. The goal is to do the following: Rate limit the amount of SSH connections that can be made ...
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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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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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How does the iptables work with IPv6?

I would like to set up a firewall on Linux Debian for IPv6. It is important to use iptables for me. I have tried to change the ipv4 folder to ipv6. How can I set up iptables for IPv6?
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package from IP arrives at certain port => open portrange to IP for x seconds

I have been toiling with an issue on iptables: I am trying to make a portrange open to a specific IP for x seconds/minutes as a result of a single packet being sent to a specific port. Not exactly ...
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601 views

How to configure Centos 7 firewallD to allow docker containers free access to the host's network ports?

I have docker installed on CentOS 7 and I am running firewallD. From inside my container, going to the host (default 172.17.42.1) With firewall on container# nc -v 172.17.42.1 4243 nc: connect to ...
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Determine what port OpenSUSE firewall is blocking

I am having a problem with the WebStorm IDE in that I cannot use its built-in FTP capabilities probably due to my OpenSUSE (Tumbleweed) firewall blocking some needed ports. I am assuming that because ...
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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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NFS Port Blocking Firewall Issue

I am a little stumped on this one and maybe I have been staring at this for too long...but I cannot get my Mac (10.10.3) machine to connect to my Oracle Linux 7 (CentOS/RH 7) server with its firewall ...
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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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Unable to access another server over local network on Digital Ocean

I have two servers. Let's call them A and B. Both are running ubuntu server 14.04. B runs percona server. Now I do not have any firewall set-up on either servers still I am unable to connect to server ...
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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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Close the neccessary Ports [duplicate]

I am using Linux Mint and I am newbie. Someone is trying to access my computer via my MAC Address and open port. I have some questions: I know that there are different type of port like TCP and UDP. ...
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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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182 views

Connection Timeout for ssh connection depending to the ip location?

I have a machine where I can connect it using ssh from different networks. But when I have moved to other country I have not be able to connect it. What may be the cause? I am able to ping the server ...
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mount times out with iptables --policy OUTPUT DROP

I previously ACCEPTed all output traffic by default. Recently changed the policy to DENY output by default, only opening ports needed for server/application functionality. When I tried to mount a ...
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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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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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how to automate creating firewall rules?

There is a complex live system - few vlans. In each of them there are linux servers, and on every server there are services. Services connect together - for example service http on host A connect to ...
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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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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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Impossible to browse web after configuring iptables

I'm trying to configure iptables on my ubuntu computer. These are my rules: Chain INPUT (policy DROP) target prot opt source destination ACCEPT tcp -- anywhere ...
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Email evading my spam filter

I'm having trouble with email evading my Barracuda Spam firewall. I believe the spammers are using my A Record to bypass my MX Record which is what directs email to my Barracuda for processing. How ...
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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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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 ...