Questions tagged [firewall]

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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How can I prevent certian IP from connecting to iSCSI target server by ufw?

I set up a iSCSI target with targetcli. I would like to pass all connections to access target storage but a few IPs. I did it as below: ufw allow 3260/tcp ufw deny from 192.168.0.112 to any port 3260 ...
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iptables-restore v1.6.1: Can't use -i with OUTPUT

The line for the loopback interface is -A OUTPUT -i lo -j ACCEPT but the error iptables-restore v1.6.1: Can't use -i with OUTPUT shows up
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UFW denies SSH even though rules allow

I have recently configured my RaspberryPi 3 to only allow connections through VPN. I would however like to open it for SSH connections from anywhere. The rules below should allow traffic on port 22, ...
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30 views

How to block all incoming and outgoing traffic except outgoing of 80 port and 443 in ufw?

I need to unlock only outgoing 443 and 80 port, only for navigate through internet, actually im using the rules: ufw default deny incoming ufw default deny outgoing ufw allow out from any to any port ...
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Is there a way to tag any specific application's traffic with DSCP/ToS

I recently made the switch from windows to linux (Manjaro). To manage traffic I had been using a windows feature that allowed me to specify the name of an application so that its network traffic ...
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How to control internet access of each app? [duplicate]

How can I control internet access of each app in my fedora 30 ?And how can I completely block internet access of an app?
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Local Chrony server and client not syncing

I'm trying to demonstrate a simple Linux local network with some most used services on it. I have two virtual machines (Fedora Server 30): A, B. I have configured A to act as a router in the network ...
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Virtual network virbr0 cannot connect to internet anymore

I have VMs in virt-manager. Normally, they can connect to the internet. These VMs are connected to my default virtual network, device virbr0. To reach the internet, the virtual network is configured ...
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No Route To Host from one VM on LAN

I'm quite stumped/frusterated as I can't get postfix to work on one of my VM's. It is a "template" VM and I have setup other VM's with this template fine. The only difference I can really think of is ...
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Add exception to UFW Firewall for python http server directory listing in Route IP 10.42.0.1 Ubuntu?

i'm trying to list a directory using this python command: sudo python3 -m http.server --bind 10.42.0.1 80 But, ufw firewall blocks the traffic of the route ip 10.42.0.1, and the devices connected to ...
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40 views

ufw blocks wireguard

I have set up wireguard and ufw using this guide. But if ufw on the vpn server is enabled it blockes some packets below (internet through the vpn on the client doesnt' work). If it is disabled it ...
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UFW Drop inbound ICMP requests from outside the local network

How do I use ufw to drop inbound icmp traffic from outside my local network? Local network/mask is 10.0.2.0/24.
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How do I allow all machine from current network to access to fedora server?

I have a Fedora Desktop machine (192.168.16.109), on which I'm running VirtualBox which is running Fedora Server edition (192.168.16.112) for development purpose. There's bridged connected selected in ...
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How to fool the bridge to redirect packages of a IP not owned by any interface

I want to redirect the traffic between interfaces over a virtual bridge, when a specific match of IP and port pass through. For instance, when I connect to 10.20.30.40 on port 2222 inside a guest ...
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iptables --dport option not working

I am trying to set a few iptables rules on my Raspberry Pi running Raspbian stretch, but I have difficulties to restrict rules to destination ports. The following rule is accepted: pi@raspberrypi:~ $...
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Can't log in via SSH after reboot!

I turn on firewall with ufw with "systemctl enable ufw; systemctl start ufw" and "ufw enable". Then I set it with "ufw default deny incoming" to stop the incoming traffic. In the meanwhile, I allow ...
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Iptables hangs winecfg

I recently started using iptables and i found that when running the wine command winecfg it freezes until i disable the iptables service. I also saw that applications like tshark freeze when ran. How ...
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Can't curl without port 80 open, but port 80 shows as open anyway

So I made a apache server and put a page up, and it should be accessible on port 80 (so default), and I should be able to curl it. Apache listens on port 80 (/etc/httpd/conf/httpd.conf) But when I ...
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101 views

How can I install gufw on fedora?

I want to install gufw on my Fedora, but I do not know how to do that. I tried to install with the dnf package manager command but it doesn't work and gets this output: No match for argument: gufw ...
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How to enable firewalld without breaking application?

I have multiple CentOS 7 machines in the same LAN. Each one is communicating with a few others and having one or more applications installed that each listen on various ports (database, webserver, ...
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KDE Connect Not Working [Ubuntu 16.04] : KDE Connect is not discovering phone and vice versa

I have installed the KDE Connect application on my desktop and on my phone [Xiaomi Redmi 3S Prime]. However the desktop application would not detect my phone and vice versa. I have checked the ports. ...
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How to stop mangled output packets from using default route?

I have a router. It has a few interfaces. One of them is the VPN called vpn0, one is the default route to the physical interface, called out0 and an input interface in0. Packets from in0 with ...
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Why is my FWKNOP SSH set up not working?

I'm learning about port knocking and SPA. I'm following along with a guide, everything seems to be working fine until I close down my ports on my server. I am running two ubuntu servers on VirtualBox ...
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SSH drops randomly

An SSH connection to a particular server drops randomly (usually 20-60 seconds after login). Between the client and the server is a Palo Alto firewall with SSH decryption disabled. What I tried so ...
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1answer
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vnc dynamic runtime firewall ports >= 5901

In RHEL/Centos 7, TigerVNC-Server only needs 5901/tcp for desktop:1, then 5902/tcp for desktop:2, and so on. I think any VNC-server would operate the same way. If no one has typed vncerver for ...
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Firewall Blocking NATed Traffic Suddenly after adding a NIC

I have home a server that used to have one NIC, but I added a second one to give a dedicated link to the TV tuner. I went from having eth0 (the onboard NIC) to enp7s0 (the new NIC) and enp9s1 (the ...
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how to get ethernet interface name, why do they vary from eth

On a dell pc, the only ethernet interface off the motherboard shows up as em1. On a newer supermicro server, the interface names are enp137s0f0 On some older supermicro servers, they are eth0..eth3 ...
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How does route-to work in the BSD pf firewall?

I've recently learned about the route-to functionality in the pf firewall, and I wonder how it works. Is it similar to the "policy-based routing" system in linux? How does route-to allow the ...
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Creating Iptables rules for router in front of several servers

I'm trying to create a test environment for some software I've written and I'm running into issues with creating the right iptable rules. I have a router that the rules are being written too, and I ...
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1answer
95 views

Matching vlan id and priority with ebtables

I am attempting to use ebtables to match a specific VLAN ID (non zero) along with a specific VLAN PCP value. I tried the following: ebtables -A FORWARD -p 0x8100 --vlan-id 5 --vlan-prio 3 -j DROP ...
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Firewalld not printing active zones

On a vagrant Ubuntu 18.04.02 box: root@ubuntu-bionic:~# firewall-cmd --get-active-zones root@ubuntu-bionic:~# firewall-cmd --list-all public target: default icmp-block-inversion: no interfaces:...
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Does firewalld require system reboot for changes to become effective

On a vagrant Ubuntu 18.04.02 box root@ubuntu-bionic:~# ss -tulanp | grep -i 3306 root@ubuntu-bionic:~# docker run -d --rm -e "MYSQL_ROOT_PASSWORD=root" -p 3306:3306 -v mysql_volume:/var/lib/mysql --...
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299 views

iptables to allow traffic from one country only

I would like to allow traffic from one country only. I have seen and read online multiple ways, but most of them are outdated (with Xtables-addons), and the other half show how to blacklist IPs that ...
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How to open a port to specific IPs in iptables while using docker?

I have a postgreSQL database inside of Docker that I don't want to expose it to the host network as it causes all users to see the exposed database port. (For now I don't have a pfsense or anything ...
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181 views

Best way to filter/limit ARP packets on embedded Linux

I have an embedded Linux on some network device. Because this device is pretty important I have to make many network tests (I have a separate device for that). These tests include flooding my device ...
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346 views

How to prevent iptables and nftables rules from running simultaneously?

I'm trying to set up a firewall on my own desktop (currently I'm tinkering with a Fedora 29 virtual machine). I would like to have it on the "deny-everything-by-default" basis. Almost immediately I ...
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1answer
48 views

How do I find out which process opens a specific port on a specific IP address once in a while?

Once every 5 minutes or so a process on my machine, with my main user id, tries to open a connection to an unknown IP address (no rDNS) at an unusual TCP port (>1k). I can see this in the computer's ...
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200 views

ipset How to add IP range from x to y

I need to add this 81.212.0.0/14 ip range to ipset. But it doesnt calculate lower than /16. I want to add from 81.212.0.0 to 81.215.255.255 IP addresses. Is there any other way but /14. Im trying to ...
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iptables to ip6tables

How do I turn my iptables rules to ip6tables rules? I am getting a Bad Address: iptables -A OUTPUT -p tcp -j ALLOW iptables -t nat -A PREROUTING -d 192.168.0.0/24 -i eth0 -j DNAT --to 192.168.255....
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Does routing table work like a per-IP-address firewall, while iptables work like a per-port firewall?

I heard that in a routing table, we can drop packets. Does that work like a per-IP-address firewall to prevent access to certain range of IP addresses from the local device? In comparison, does ...
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Filter PPPoE packets

Can you somehow inspect PPPoE packets and then filter them with iptables or other tools? PPPoE is below ipv4 so I can't use iptables directly.
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Should I remove ICMP Protocol from firewall rules base on security concern?

As you can see from the screenshot of GCP firewall rule page, should I remove ICMP Protocol from firewall rules base on security concern? Will it lower the chance of being attacked? I'm using CentOS ...
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Where are iptables rules fetched from while running command 'service iptables save'?

I have created my own file- /etc/sysconfig/iptables-config. On service iptables save my rules are successfully updated and that updates the /etc/sysconfig/iptables file as well. Now even after i ...
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1answer
55 views

Virtualized firewall on KVM

I have few vms (homelab) virtualized with KVM (CentOS7) and connected to my home network. Lately I tried to isolate them by putting them in separate network and I wanted to do so with virtualized ...
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Remote access to a music player from behind a firewall

I'm supposed to set up a broadcasting center at my school. The setup is as follows: a main server (boss) that I have a shell account on (no root tho), with 250mb of free space for my account which ...
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272 views

How to implement iptables on lxc-container?

I installed lxc-container (fedora 29 amd64) on my ubuntu 18.04 system. The linux container had no firewall command line tools. Therefore I installed iptables into my container and it installed ...
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2k views

“Not running dhcpcd because /etc/network/interfaces defines some interfaces that will use a DHCP client or static address”

Deployment: VM -- (eth0)RPI(wlan0) -- Router -- ISP ^ ^ ^ ^ DHCP Static DHCP GW NOTE: RPI hostname: gateway • The goal was to make VMs accessible from the outside ...
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1answer
50 views

Firewall software similar to Outpost for linux

I'm corrently using Windows for my machines with Outpost firewall(Agnitum), but want to switch for linux(not sure what disto yet) and would love to know from you what are my options with linux's ...
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gufw GUI fails to launch on LMDE

After upgrading from LMDE2 to LMDE3 Cindy I noticed I could no longer launch the gufw GUI. The error was: ** (gufw.py:20536): WARNING **: Failed to load shared library 'libwebkit2gtk-4.0.so.37' ...
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Can't connect to OpenLDAP

i have installed iRedMail with OpenLDAP managing the Mail Accounts. So far that works. Now I wan't to connect other applications to that LDAP and I'm trying to use a LDAP Explorer "LDAP Admin" for ...