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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13 views
Firewall everything except ssh and rdp traffic on a specific interface
I only want to allow local ssh and rdp traffic on my eth0 interface. I've configured sshd to only listen to port 2222 but I have not done anything for xrdp. But I know that xrdp speaks through the ...
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0answers
9 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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1answer
18 views
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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0answers
11 views
TCP connections in SYN_SENT not visible with lsof
I have lots of connections in SYN_SENT:
$ conntrack -L | grep -c 'SYN_SENT'
conntrack v1.2.1 (conntrack-tools): 28100 flow entries have been shown.
14017
But I can't see which process(es) are ...
3
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2answers
39 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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0answers
20 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 ...
2
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0answers
42 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
...
4
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3answers
37 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 ...
1
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0answers
8 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 ...
0
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1answer
37 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
36 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 ...
1
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0answers
32 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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0answers
23 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 ...
1
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1answer
65 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 ...
1
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1answer
117 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 ...
0
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1answer
17 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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0answers
18 views
redirect all ARP traffic from eth0 to eth1
I would like tredirect ARP traffic. Im struggling with arptables and ebtables but i cant see the light :)
I have 2 interfaces :
eth0 10.10.10.25
eth1 10.10.10.20
Both in 10.10.10.0/24
I want to ...
1
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2answers
31 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 ...
0
votes
1answer
49 views
Stateful user-space firewall for Linux
Is there any stateful user-space firewall for Linux?
I'm looking for a firewall that doesn't rely on anything in Linux kernel (like iptables/netfilter) and works with raw packets.
1
vote
1answer
47 views
Open UDP Ports; Can I Close Them?
I'm trying to secure my internet browsing. I just reinstalled Xubuntu 14.04 and GUFW firewall. I have 8 UDP ports open. I don't understand why. The software I currently have open are Firefox, GUFW, ...
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1answer
17 views
What port uses my backportpackage or bzr?
I am working in a company what uses Ubuntu Precise on the desktops behind a proxy. The Proxy is available in /etc/environment and set as: http_proxy, https_proxy, ftp_proxy, no proxy and their ...
2
votes
1answer
101 views
How to use both syn proxy and connlimit rules with iptables?
I want to write both syn proxy and connlimit rules. I want to send packets to syn proxy first because of performance issue.
Here is rule sample. I use bridge interfaces but I dont think it is ...
0
votes
1answer
12 views
kernel security and IDS Firewall + AV together or not?
I try to hardening my server. For doing so, I got a general question: Should I install kernel security patches like selinux and an Anti-Virus with Intrusion Detection Firewall? Does it make sense to ...
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0answers
85 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
...
0
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1answer
68 views
Which port to open for Google HangOut Video Conference
We need to open the necessary ports for Google Hangout VIDEO Conferencing in our firewall. Unfortunately my netmon trace shows Port 51355 and 51336 to be active; which is not at all what the Google ...
3
votes
1answer
277 views
Changed SSH port without allowing it through firewall, locked out now - what to do?
I have a VPS where I changed the SSH port from the default 22. Unfortunately I forgot to allow the new port through the firewall. I don't have physical access to the server, and my host does not seem ...
1
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0answers
40 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 ...
3
votes
0answers
63 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 ...
0
votes
3answers
163 views
what is dhcpv6-client service in firewalld, and can i safely remove it?
In a CentOS 7 server, I type in firewall-cmd --list-all, and it gives me the following:
public (default, active)
interfaces: enp3s0
sources:
services: dhcpv6-client https ssh
ports:
...
2
votes
1answer
136 views
blocking all but specific ips from specific services in CentOS 7
In a CentOS 7 web server that needs to remain totally closed to the public, I need to block all ip addresses and then only allow specified ip addresses to access specified services. How can I ...
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1answer
133 views
Block all but specified range of ip's input to an specific port [duplicate]
In a CentOS 7 web server, how do I configure firewalld to block all but a specific list of ip addresses from making successful http or https requests?
I know that I can use httpd.conf to restrict by ...
0
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1answer
100 views
how to make firewall changes permanent via firewall-cmd?
I am trying to open some ports in CentOS 7.
I am able to open a port with the following command:
firewall-cmd --direct --add-rule ipv4 filter IN_public_allow 0 -m tcp -p tcp --dport 7199 -j ACCEPT
...
1
vote
1answer
17 views
libvirtd and filtered ports
I am new to virt-manager.
After having configured a virtual network (new interface virbr0) with 2 VMs that should be able to communicate, I discovered that most ports are filtered.
For example, the ...
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0answers
73 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 ...
0
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1answer
39 views
iptables INPUT command
On a machine called ubuntu1, this is the iptables command:
sudo iptables -A INPUT -p icmp -j DROP
on the other computer (xp1) I can not ping the ubuntu1.So this is OK.
But On ubuntu1 can ping xp1. ...
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0answers
22 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 ...
1
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2answers
43 views
iptables is ignoring rules?
I've found some strange traffic through tcpdump (traffic is ongoing always):
13:00:13.203754 IP 1.2.3.4.1028 > 188.113.188.16.56881: UDP, length 103
13:00:13.204396 IP 1.2.3.4.1028 > ...
0
votes
1answer
380 views
CentOS 7 Firewalld zone configuration for private web application
I have read all the man pages related to firewalld and also explored all of the files that come pre-installed in firewalld before it is configured. How can I configure the zones of the firewall to ...
0
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0answers
37 views
OpenVPN on Ubuntu VM
I am trying to create a VLAN Network from my home network for a web-dev platform. I am running Ubuntu servers in VirtualBox on a Windows 7 machine.
I am running an Ubuntu DHCP/OpenVPN/Shorewall ...
1
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1answer
32 views
Iptable forward interfaces for gateway machine
I have two Ethernet interface being configured to use as system gateway
ex:
eth1: 10.10.1.0
eth2: 10.10.2.0
I want to forward all the packets which are coming to the 10.10.2.0 gateway contacting ...
1
vote
1answer
121 views
Assp won't start
I tried to install ASSP (Anti-Spam SMTP Proxy Server),but when I try to start it I get the following:
$ perl assp.pl
Perl version 5.012003 (5.12.3) is at least recommended to run ASSP 2.4.3
(14313) ...
0
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1answer
175 views
viewing firewalld logs via remote login to CentOS 7 server
I have firewalld installed in a remote CentOS server. When I log into the server over the internet as root, I type the following command to access the firewalld logs:
journalctl ...
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0answers
380 views
Network firewall on CentOS, host cannot be resolved?
I have a centos machine and I am trying install some dependencies using yum. When I do this I keep getting a message saying the host cannot be resolved. I was told the previous person that used the ...
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1answer
45 views
Application specific DNS problem?
I'm working on a live stream transcoder application using nginx + ffmpeg.
Everything works fine when I use avconv to transcode, but if I use ffmpeg, I get this error:
[tcp @ 0xb4e9da0] Failed to ...
1
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1answer
81 views
Allow wifi connections only to a local service, don't route to the wired ethernet
I have a Raspberry Pi running Linux (Raspbian) which is connected to my corporate Internet over an Ethernet cable. The RPi also has a wifi adaptor plugged into a USB port. I've been following along ...
1
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1answer
694 views
log files in CentOS 7 [closed]
In CentOS 7, how can I locate and view all the system logs that tell me who tried to enter the system, who got in, what processes they contacted, what they accomplished, etc. I want to be able to ...
2
votes
2answers
173 views
outgoing SMTP 25 port blocked by ISP?
I just setup postfix but I just realized my ISP outgoing blocks port 25 (SMTP). How do I send email outside? I can see my mail queue is filling up. Any suggestion?
1
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0answers
90 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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0answers
49 views
Port randomly closing (iptables)
I'm running CentOS 6.5 on a VPS and one of the services I have running is murmur/mumble (A voip application). The issue I'm having is that the port clients connect on will be open when I initially ...
1
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1answer
22 views
Linux firewall techniques: MySql-Account
I'm having a discussion with a software developer in my nears. He is using MySql direct connections for a software. There is no PHP/SSH/whatever-Bridge involved for the communication, neither at ...
