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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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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173 views

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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1answer
443 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 \ new-connection-mark=...
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1answer
524 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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1answer
723 views

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
149 views

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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1answer
76 views

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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1answer
127 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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1answer
599 views

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 euid=...
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2answers
257 views

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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1answer
94 views

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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1answer
86 views

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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3answers
130 views

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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1answer
129 views

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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2answers
5k 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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2answers
577 views

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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0answers
108 views

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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1answer
877 views

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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301 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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1answer
252 views

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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1answer
204 views

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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506 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 192....
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2answers
1k 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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1answer
180 views

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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585 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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140 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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3answers
289 views

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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514 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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51 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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2answers
266 views

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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1answer
67 views

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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275 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 ...
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0answers
155 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: SFW2-...
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1answer
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How iptables tables and chains are traversed

I know linux has 3 built-in tables and each of them has its own chains as follow: FILTER: PREROUTING, FORWARD, POSTROUTING NAT: PREROUTING, INPUT, OUTPUT, POSTROUTING MANGLE: PREROUTING, INPUT, ...
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2answers
131 views

How to disable network access for a user?

Trying to disable the network access for the user: [root@notebook ~]# iptables -I OUTPUT -m owner --uid-owner tempuser -j DROP [root@notebook ~]# ip6tables -I OUTPUT -m owner --uid-owner tempuser -j ...
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45 views

Forwarding packets through a host

I've setup a Site-to-Site network using this How To This How To fits exactly what I need. But I've a problem. From site wich hosting the OpenVPN AS server (site 2, right in the howto) I can't ping a ...
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68 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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3answers
247 views

OpenBSD's pf: disable network access for a given user, except for ssh.

If we are using the default firewall for OpenBSD, how can we modify it to disable all the network access for a normal user except for one thing: we want to ssh to the user from random hosts! So ...
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0answers
137 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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1answer
398 views

IPTables Firewall/Router/Gateway needing to block outbound traffic from users

I have multiple ethX interfaces. eth0 is connected to the internet. eth1 is connected to a trusted network. eth2 is connected to a network I need to impose usage rules. What I'd like to do is ...
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1answer
615 views

How to open server port on RHEL 6.6?

I am trying to open a port (tcp 27017) for access to mongodb on a newly created RHEL 6.6 instance at Amazon AWS. Following mongo docs, I did: sudo semanage port -a -t mongod_port_t -p tcp 27017 I ...
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180 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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1answer
662 views

PPTP Through IPTables

If this has already been answered, I apologize, I could not find an answer to this during my searching. I am new at Linux/Unix and I have recently implemented a Raspberry Pi firewall/gateway on my ...
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1answer
1k views

firewalld settings for OpenVPN with https, ssh, and smtp

I am configuring a remote CentOS 7 webapp server to wrap https and ssh inside OpenVPN, while keeping smtp running outside of OpenVPN. I notice that, when I establish an OpenVPN connection from a ...
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1answer
522 views

multiple user-types/access-rules for OpenVPN on CentOS 7 and firewalld

How can I define separate roles for users and administrator in OpenVPN running on CentOS 7 server? Specifically, the users must only be allowed to https, while the administrator must be allowed to ...
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1answer
393 views

How can I set up the ULOG target with iptables and MySQL

I'm running CentOS 6.6 32bit as a firewall box using iptables. I want to be able to use the ULOG target to store dropped packets in a MySQL database for statistical analysis. After much Googling I ...
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158 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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2answers
38 views

FTP and WWW services don't acknowledge connections

I have Lubuntu 14.04 LTS with vsftpd and the lamp stack (apache2, etc.) installed. Everything works fine on the LAN. Externally, the services don't acknowledge connection attempts. I can see packets ...