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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iptables logging for all except ICMP

I have iptables firewalls and its logging for all DROP packets or Deny. I want to tell it to no LOG any packet for ICMP protocol. How do i tell that *filter :INPUT DROP [0:0] :FORWARD ACCEPT [0:0] ...
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22 views

firewall configuration to prevent a server-client malware connection

can i prevent a malware to connect on my pc simply setting ''incoming traffic to deny'' and allowing only outgoing traffic? I red that a malware could use the port knoking tecnique, but with a GUI ...
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0answers
49 views

How to Limit the hit-rate of connection for “X-Forwarded-for” IPs?

I have Apache, which is behind the Amazon ELB which forwards the IPs as in "X-Forwarded-for" header. I found some articles around to do the hitrate limitation but i doubt they are all for real IPs, ...
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30 views

Limiting number of simultaneous connections system-wide?

In my dormintory, I've got a not-so-nice networking environment, in which I'm identified only by mac-address of my ethernet card. In said environments, some limits of simultaneous opened connections ...
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0answers
69 views

UFW Preventing Web Browsing

I have the following rule set configured using UFW on Debian Jessie 8.2.0: Status: active Logging: on (low) Default: deny (incoming), deny (outgoing) New profiles: skip To ...
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2answers
134 views

Route incoming and outgoing on same interface

My router currently provides the NAT to all the PCs and the Ubuntu desktop (with some server functions) in the network. I want to use the Ubuntu system as a proper firewall, but it only has one ...
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1answer
39 views

How do I configure my server to stay hidden unless it receives correct password?

The server is supposed to silently ignore any requests (including ping) unless it receives correct credentials with initial request. Nobody else can tell that the host even exists. I am talking about ...
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1answer
463 views

Firewall blocking SSH/SFTP connections. How to cheat it?

Hi folks (sorry for the bad english) I'm a college student, and I live in the student's house of my university. I study computer science, and there we have the right to a space in a nfs server to ...
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27 views

how to set the ip tables for two vpns connected togheter

Immagine this scenario: two vpn. The first vpn is on the host sistem and the second is on a virtual machine. I want to connect to the first vpn and then to the second vpn on the VM, so i set ...
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0answers
27 views

Forward public network around current network

For the purposes of this discussion, I have a very current always-on linux machine with two nics: wifi0 eth0 A very crude diagram of my desired configuration looks like this: ...
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1answer
76 views

how to set ufw firewall/iptable rules for a VPN Server to be explicit in allowing certain connections?

I want to connect to a VPN. I want to enable ufw firewall or iptables so that there is no connection that goes out of the VPN tunnel or that comes in (except that for VPN server). Could you ...
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2answers
43 views

Domain only for web server

I have a domain which i want to point to my server. But i don't want to allow other people to use this domain to reach the server, only specific ports on the server (web server, so port 80). So if ...
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2answers
93 views

Best practises: Applying iptables firewall rules for SSH

I need to add some firewall rules in our QA environment using iptables. I have to do the changes remotely . Some of the changes also include disabling SSH for few Networks . What are best practices ...
2
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1answer
417 views

Why does iptables accept packets on a given port, when it is closed?

Here is my situation. I have a public address on my router and have manually forwarded a given port for torrenting, so not via UPnP, that is disabled both in the router and the application. It works ...
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1answer
177 views

How to set up a clear SuSE-Firewall?

I’m doing some rules in a machine with the firewall disabled, but when I run rcSuSEfirewall2 a lot of rules and policies are applyed by default: iptables -L Chain INPUT (policy DROP) target prot ...
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1answer
250 views

ufw won't allow connections to port 5432

I've installed Postgresql 9.4 on Ubuntu Trusty from the PGDG ppa. I've created a database and set it listen-addresses to '*'. I've made an entry in the pg_hba.conf file. I can connect locally with no ...
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0answers
23 views

Separation between the User machine and Server machine by another linux for monitoring

I am planning to have three virtual machines with virtual box (m1, m2,m3). I already installed on m1 = Windows XP Home Edition, and on m2 = LUbuntu 15. The big picture is this : m1 : a user m2 : ...
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1answer
45 views

Firewall Rule Testing - telnet failing

I am testing firewall rules but the telnet is failing. The firewallrules have been implemented but the target server is not listening on the servers. How can I enable the target server ports to ...
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1answer
290 views

iptables - how to drop protocols [closed]

I have the desktop-server Debian Jessie machine running for testing purposes just for 19 hours now. I have already set a few rules as you can see above. But I am not really into networking. So it ...
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0answers
115 views

iptables: block communication with others in same subnet

I have a couple of devices in my subnet (e.g. 192.168.0.0/24) and would like to make sure that one of these devices (identified by MAC or IP) can only talk via the router (where I'd like to set up ...
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0answers
148 views

Wireless ssh “issue” (No route to host)

I installed Debian Jessie (gnome) on one of my machines today and it went smoothly except for the wifi. Calling this machine A, I set up an ssh connection with machine B (using an rsa key) and then I ...
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1answer
455 views

iptables - why do I get “Table does not exist (do you need to insmod?)”

I need to install some iptable ruels to block traffic that originates from a certain country, I found this script example on http://www.cyberciti.biz/faq/block-entier-country-using-iptables/ it works ...
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1answer
80 views

Iptables rule to drop packets to and from local network

I want to set a virtual machine on laptop, but I don't trust the guest system fully, so I would like to block it's access to local network (to network 192.168.0.1/16 or 10.0.0.1/8 or ... the other one ...
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2answers
203 views

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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3answers
159 views

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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2answers
81 views

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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1answer
75 views

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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48 views

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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3answers
480 views

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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0answers
278 views

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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2answers
3k views

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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2answers
90 views

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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41 views

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 ...
2
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1answer
131 views

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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1answer
624 views

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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2answers
3k views

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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1answer
169 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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1answer
157 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 ...
2
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1answer
397 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 \ ...
4
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1answer
452 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
624 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
139 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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0answers
106 views

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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1answer
73 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 ...
0
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1answer
118 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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536 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 ...
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2answers
225 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
90 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
80 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 ...