Questions tagged [iptables]

Iptables is used to set up, maintain, and inspect the tables of IP packet filter rules in the Linux kernel.

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Port redirection while blocking the dest-port externally

This might be simple but after spending ~5 hours w/ iptables and googling, I couldn't make it work, so I thought I'll ask here directly. I have an ubuntu machine with Docker installed (so it ...
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Using iptables to block all internet-originating traffic except for a specific port

I have an Emby server running on Ubuntu Server 20.04 LTS and would like to configure iptables to block all incoming connections from the internet except for port 8920, but allow normal incoming ...
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Desperate, attempt to install iRedMail, now xrdp blocked

Please help! I have a semi testing machine: Ubuntu 20.04.2 with gui, virtualbox and other stuff to play with. At startup windows guest loads just to show home security camera. Whenever I want to "...
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Having to reopen ports on reboot

When I restart my computer I keep having reopen ports using iptables. Using a "sudo ufw allow [port]/[protocol]" doesn't open the port and isn't persistent. Pertinent info 20.04 Was ...
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How to make routing persistent for multiple NICs in Ubuntu Server 20.04 with netplan?

I'm trying to set up the routing for my server to different public IP addresses. The configuration of my first network works fine. The second is also configured with the right static IP after boot. I ...
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Unable to add rules to /etc/ufw/before.rules and before6.rules

I run a high-traffic NTP server and the following rules are absolutely necessary to prevent my conntrack table from being immediately overrun (regardless of how large it is): iptables -t raw -A ...
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iptables - help me figure out if my forwarding scheme is correct?

I want to forward everything from wlan0 to tun0, and everything from tun0 to wlan0. Using sudo iptables -S command, the output is:(assuming this is the actual rule of my iptable) -P INPUT ACCEPT -P ...
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Purge IPFS 100%

I'm trying to remove IPFS from my Ubuntu 20.04 system. I have: Removed the config files at /root/.ipfs Remove the ipfs binary at /usr/bin/local Blocked udp 4001 on iptables However, after checking ...
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iptables port forward to diferent box port

Hy everyone! I have a home network, and have a DVR (provison) connected with my cameras. I can access to my dvr via internet/lan, but the dvr don't have any security options except fixed ips or ip ...
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why does UFW block ICMP destination-unreachable messages despite apparently having rules to allow them?

Ubuntu 20.04.2 LTS, I am running UFW with mostly default configuration, have allowed some ports through with "ufw allow" but haven't done any manual blocking or config files editing. I was ...
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IPTABLES/UFW: Deny ssh (on alternate port) requests from WAN, and allow ssh (on alternate port) from LAN. HOW TO?

I am running Ubuntu server version 20.04. I have configured my ssh server to listen on an alternate port (port 40001) in my sshd_config file. I want to allow incoming traffic from anywhere on my local ...
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iptables - firewall configuration - Ubuntu Script 18.04

I need help with configurating iptables. I've made some progress which i think might work like, but i'm not sure. Looks like this: #!/bin/bash #changes NET="10.10.10.0" ADMIN="10.10....
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Bad argument `DROP' iptables

i have question i need help question is Build a firewall to filter traffic between two networks (Network A and Network B). Please note that you need to use the FORWARD chain. Please consider the ...
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iptables does not start after reboot

I already run the command, systemctl enable iptables and systemctl start iptables. but iptables service was not started as message below after I reboot server. please kindly guide how to check and fix ...
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SSL certificate only works on a port

I use an SSL certificate from Letsencrypt and this worked for me forever. Today an error has occurred that the SSL certificate is not secure. I use webmin as Control Panel and when I access webmin ...
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UFW status is getting problem running iptables

I want to use UFW (version 0.36) but I get this error when running ufw status: ERROR: problem running iptables: Another app is currently holding the xtables lock. Perhaps you want to use the -w option?...
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Use Ubuntu server to access remote site

I saw related posts, but I need specific help because I can't solve this problem by myself. Google Cloud Platform. A Ubuntu server with Strongswan installed and a virtual ethernet adapter. And SNAT ...
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WiFi AP's have no internet connectivity after seting up IPTABLES

I have set up an Ubuntu 20.04 SERVER to act as a Gateway/Router. Now that the gateway is functioning, I now no longer have WiFi access via several AP's in my house. I am able to connect to the AP's, I ...
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How to test to see if packets are moving between two ports on a dual port NIC

I'm trying to set up a home router on Ubuntu 20.04 Server. I have followed dozens of on-line tutorials, and for the life of me, I can't get this to work. As soon as I get everything set up, nothing ...
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Ubuntu 20.04 gateway, iptables NAT and port forwarding

i am in a maze, i try in vain to setup the rules to be able to acces from internet my internal web server (192.168.12.10). at home, i have an Ubuntu 20.04 gateway (192.168.12.1) with two interfaces : ...
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What are best settings for “System Configuration Module: Connections” with wired connection?

2 weeks old newbie here, 20 years Windows user. Still struggling a bit... I use wired connection: first I connected from computer to modem, but found in some posts that it's safer to use router (since ...
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Route traffic through interface x based on destination ip

My computer has access to two different networks. With ethernet cable everything is routed through the company proxy server which blocks some services. But I also have an wifi-network which is ...
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Redirect Network Traffic

I host a Minecraft server at home that I use to play with friends, which they all use to connect to via an OpenVPN server. The OpenVPN server has the IP (A.A.A.A) and the IP range for the VPN itself ...
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607 views

Bad argument in iptables NAT command

I am trying to do a DNAT rule in iptables if the packet with source address 192.168.86.212 and destination address 192.168.86.212 then change the destination address to 172.217.5.100. sudo iptables -t ...
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ufw block error seen in journalctl -xe command

I'm newbie in networking and system security. I am trying to create openconnect server which tutorial is found in this link. I have also seen the similar issues like this one, but they don't make ...
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iptables script to update dyndns ip

So, I have a ubuntu 16.04 server which I want to secure with ddns iptables rules to certain ports. I did find a script and tried to alter it, because I coulnd´t get it to work. The script is as ...
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Sharing internet connection via PPP interface

I’ve been trying to share internet connection between PC1 and PC2 using iptables. PC1 connects to the internet via eth0 interface (IP 192.168.1.198 netmask 255.255.255.0) and I want to share the ...
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Cannot open port 3001 to local IPV4 ubuntu lts 20.04

I'm creating a back end app with NodeJs. My app running at port 3001. It is accessible when i try to access it with localhost:3001 or 0.0.0.0:3001 or 127.0.0.1:3001, but when I try to access it with ...
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Ping between subnets

I've created a Virtual network where there's a CLIENT---GATEWAY---SERVER The client has IP 192.168.242.141, the GATEWAY has two network interfaces with IPs 192.168.242.134 and 192.168.241.132 and the ...
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Isolate hosts on Netplan defined Bridged network

I've Ubuntu 20.04 LTS for Raspberry PI and I've created a wireless access point using the snapon wifi-ap package. That allows hosts to attach to a 192.168.8 network and works beautifully the Ubuntu ...
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Ubuntu Questions - Security - Concerns

I have a few questions that I would like to verify. I currently have a Ubuntu VM on my windows host. I am opening it up Port Forwarding so host a gitlab repo on it. I would like to be able to access ...
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Ubuntu firewall issue

I've broken my ubuntu's dns/firewall settings. I've installed toroxy and dnscrypt and after its deletion I don't have an internet connection even to my router. ping 192.168.100.1 # router address ping ...
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Failed to apply network settings you might not be able to connect

On My notebook omen 17-cbO247 core i7, I recently upgrade my system from Ubuntu 18.04 to Ubuntu 20.04. It works almost perfect, but after rebooting the system, I’m getting the following message: ...
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how to allow traffic on specific IPs for a port in iptables

I want to restrict traffic for all IPs except 10.2.3.4 on port 5041 First I gave access to the IP on the port like so : iptables -A IN_public_allow -s 10.2.3.4 -p tcp -m tcp --dport 5041 -m conntrack -...
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iptables: drop incoming UDP packets, destination port 1900

I am trying to use iptables to drop UDP packets that have destination port 1900. This shall affect both directions, so I added one rule each for the INPUT and the OUTPUT chain of the filter table. ...
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Is it possible to create daily quotas for specific websites, based on duration of usage or data traffic?

I am wondering if some rule like the following can be set up at the router level; using iptables or ipset or similar tools. (I am not very experienced in this area, sorry if the following is a bit ...
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How do I only allow outbound connections to Cloudflare IP addresses?

I have a Ubuntu 20.04.2 LTS webserver that is behind Cloudflare. I have ufw rules to only allow connections from Cloudflare IP ranges, and I want to do the same for outbound connections. I'm looking ...
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133 views

firewalld - No such file or directory

After upgrading from Ubuntu 20.04 to 20.10 I want to finally get started with firewalld instead of the old manual iptables approach, but all I get from the service is the following, which also breaks ...
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How can I block outgoing traffic to a domain with all subdomains with UFW or IPTABLES?

I need to block all outgoing traffic to a domain with all its subdomains. I tried to do something like this: sudo ufw deny out from any to *.domain.com but of course it doesn't work because it needs ...
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I have a problem with SSH (or any port) I can't fix

I own a refurbished HP Proliant DL380 G7, for a small project I've been working on (It’s the first time using a server and setting it up). But after I set up Ubuntu 20.04 on it, the first thing I did ...
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Is there any way to rollback `dpkg-reconfigure iptables-persistent rollback`

In a very-not-my-best moment, I was trying to configure a laptop following some documentation. I followed the instructions in the documentation: sudo sysctl net.ipv4.ip_forward=1 sudo iptables -t nat -...
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ufw differentiates block-and-log from unmatched log

I insert block rules using this kind of statements sudo ufw insert 1 deny log from 45.136.228.230/24 I have a few hundreds of such deny-log rules. ufw will block the IP and log the event. However, ...
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Cant install anything with current iptables rules. What am I missing?

Heres my iptables rules below. I am trying to block everything except whats needed. I am not able to apt-get install with these rules. What am I missing? sudo iptables -F sudo iptables -X sudo ...
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How to get UFW in Ubuntu 20.10 (Perhaps iptables or your kernel needs to be upgraded)

This is my Ubuntu 20.10, if I understand uname show wrong version # uname -r 4.15.0-60-generic because # ls -la /boot total 147492 drwxr-xr-x 4 root root 4096 Feb 11 21:21 . drwxr-xr-x 19 root ...
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How do I redirect traffic from the virtual tun interface to the LAN?

How do I redirect all traffic from the virtual interface (tun) to the LAN? Linux UBUNTU 16.04, eth0 (wan) eth1 (lan) virtual tun (tun2socks) adapter available I need eth0 (wan) -> tun adapter -> ...
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Can someone explain interactions between iptables, nftables and bpf?

I'm on Ubuntu 20.10 trying to do some routing config for my virtual network, and I'm confused about the interactions between the 3 main types of firewall technology used in modern Linux distros, ...
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USB dev board changes MAC address on every reboot

beginner here, I have a small embedded linux system attached to a linux mini-pc via a USB cable. The embedded board uses 192.168.2.2 as a static IP. My laptop is on the LAN, the linux mini-PC is on ...
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How do I let my client to use internet via using iptables in Ubuntu 16.04 in VirtualBox

I've got setup dhcp server who is listening for IP requests in private server. When client connects to it, he gets an IP, gateway and dns address. Server can ping him and client ping server, but ...
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Assign ipv6 addresses across a firewall without NAT

I need some advice on how to configure my system so that it can assign some of the /64 bock of ipv6 addresses provided by our ISP to devices which are behind a netfilter (iptables) firewall. Our ISP ...
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Make server globally reachable on IPv6

I've been hosting a globally-reachable Minecraft server on my desktop Ubuntu computer at home for about 1 month, on IPv4, using my ISP's router NAT configuration. Recently, my ISP (SFR, a French ...

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