Questions tagged [firewall]

a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts

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iptables to block http and ssh in one direction

I have a topology where there is a Linux as a router that connects two Linux, and I want to use iptables to filter ssh and HTTP in one direction. I used the below code but it didn't work! I really ...
masoud hanifehzadeh's user avatar
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1 answer
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Block a spcific subset range in UFW

I am looking to block a specific range in a single line .. Is that possible with UFW? I'd like to block 1.1.0.0 - 1.1.31.255, but the only way I've found to do so is to put 32 individual rules in IE $ ...
Zak's user avatar
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How do I install firestarter on ubuntu 22.04.1?

I use this distro, and I've tried sudo install but it says that the package was not found. Tried through synaptic and also not found. Has it been discontinued? 2-Is there a better front-end firewall? ...
denisPlay's user avatar
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connection to service with disabled firewall fails

i am trying to access a service on my ubuntu server 20.04 the following command on the local machine: nc -zv 127.0.0.1 9256 Connection to 127.0.0.1 9256 port [tcp/*] succeeded! the same command from ...
julian bechtold's user avatar
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Port 3003 is not working while ports 3000 - 3002 are working fine

I have several node.js apps on an Ubuntu server working just fine on ports 3000 - 3002. Now I added one more app to port 3003 and it is not working anymore. I switched the apps on port 3002 and 3003 ...
ush189's user avatar
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I can't reach my server

I have ubuntu 20.04 server hosting with nginx. My site is in word press. I was trying to install ftp by following documentation on Vultr. Suddenly, the connection with my site, lost (502 bad gateway)....
Apostolos Ximinis's user avatar
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How to find out the program from iptables log

Testing the ping on ubuntu 22.04: Host A IPv6: 1111:1111:1111:1111:1111:1111:1111:1111 Host B IPv6: 2222:2222:2222:2222:2222:2222:2222:2222 Host A: Now execute a ping from Host A with the following ...
stackbiz's user avatar
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easy firewall ufw settings for a beginner coming from windows [duplicate]

I am used to firewall on windows. everything is allowed and new apps have to ask for permission. when I look at current connections in settings' firewall tab, only a few have program names associated ...
Usermaxn's user avatar
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Install outline VPN on a NAT VPS

I'm trying to install outline on my NAT server, but I keep getting this error: Your Outline Server was installed correctly, but we are not able to connect to it. Most likely this is because your ...
kaveh faal's user avatar
2 votes
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I need a simple TCP load balancer in Ubuntu

I would like to create a load balancer for RDP connections only, that’s one TCP port only and would like to avoid anything more complex like Nginx. I don’t need cache, or anything else, just take an ...
Chema's user avatar
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I am receiving Dozens of [UFW BLOCK] Messages each second on my syslogs server

I have a Ubuntu server running currently that has suddenly seen a striking drop in incoming traffic after many months of a high average. I have noticed in my logs that dozens upon dozens of UFW Block ...
Chestnut Rice's user avatar
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ssh: connect to host ********* port 22: Connection timed out

I have Ubuntu 22.04 newly installed on my laptop. I am trying to connect to a remote server and getting the following error: ssh: connect to host ********* port 22: Connection timed out I tried some ...
Maliha Kabir's user avatar
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DDoS Attack - Iptables bad configuration

I have Ubuntu 20.04.4 LTS. I am under a DDoS attack and don't know how to limit the connections made by multiple IP's (avobe 500). I saw some post, like this or this, but don't know how to follow the ...
Mario Navarro Claras's user avatar
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Unable To Connect To Internet Sites Via Live USB - Wi-Fi Settings Are Correct

I was running my Ubuntu Live via USB for the first time. All of my Wi-Fi settings were correct and I was able to get a DHCP address on my network but I was unable to get to any Internet URL including ...
mbdavis313's user avatar
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Your Outline Server was installed correctly, but we are not able to connect to it

I'm trying to config Outline VPN and I bought a Droplet from Digitalocean with Ubuntu 22. So, my server generated URI string correctly: CONGRATULATIONS! Your Outline server is up and running. To ...
Kiyarash's user avatar
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Why am I able to connect to Wi-Fi(router) without any issues while all the In/Out traffic is blocked with UFW

When I block all the traffic with ufw, e.g.: ufw default deny incoming ufw default deny forward ufw default deny outgoing I can't receive or send anything, but I still able to connect to my home Wi-...
askingUbuntuAboutKubuntu's user avatar
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Can't access Ubuntu Server with SSH after doing something with iptables

I'm trying to run a MC-Server on an Ubuntu Sever (Oracle Cloud). I already port forwarded 25565 and 22 but still couldn't access the server. I found these commands on another tutorial, but when I ...
Julian M's user avatar
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iptables/ ufw problem with getting emails

I have a very difficult problem that I can't seen to solve. I have an Ubuntu Server 20.04.5 LTS set up as a firewall/ router, so it has two interfaces. One internet connected and the other lan ...
Jabin's user avatar
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My Ubuntu Server Ports got locked

I just tried to join to my Jenkins on my VPS as usual. When I try to access the URL it returns the error code ERR_CONNECTION_TIMED_OUT. This happens as well with port 8080 for my website and other ...
Joanmi's user avatar
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DNS only works when I have a port 53 UDP outbound rule *AND INBOUND* rule

I'm locking down both inbound and outbound ports with iptables -P INPUT DROP iptables -P OUTPUT DROP Then, I allow certain traffic to certain servers SSH from my network to the server (inbound) HTTP ...
geekygeek's user avatar
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Should I be concerned about these UFW blocked traffic?

I just installed ufw on a newly provisioned Ubuntu 22.04 Server. It is currently set up to deny all traffic except ssh on an alternate port. I'm getting this pattern of blocked traffic: Oct 6 10:09:...
William Oliver's user avatar
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DNATing DNS requests that aren't going to a particular server. iptables : No chain/target/match by that name

I have some chains that I create in iptables iptables -N dns-requests iptables -N wg0-filter I then create a filter, to pass DNS traffic that are on Port 53. iptables -A wg0-filter -p tcp --dport 53 -...
geekygeek's user avatar
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ufw not logging on ubuntu 22.04

I have no ufw logs on my minimized Ubuntu 22.04 server. sudo ufw status verbose output: $ sudo ufw status verbose Status: active Logging: on (low) On the internet I found I need rsyslogd enabled. On ...
unixcandles's user avatar
4 votes
2 answers
1k views

Ubuntu 20.04 Server UFW does not activate automatically

Lately, I've noticed that UFW is inactive until I activate it manually. I've run ufw enable multiple times, checked that ufw.service is active, but it still does not start on boot. Output of systemctl ...
Emre Talha's user avatar
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756 views

How to disallow connection by ip country except one?

I want to disallow incoming connection from all country except one. I know https://www.ip2location.com/free/visitor-blocker and what files I have to download and allow and select 1 country. Then how ...
J.Col's user avatar
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usg ufw conflict rules

I ran a usg audit (following https://ubuntu.com/blog/cis-security-compliance-usg) sudo usg audit cis_level1_server See audit result here I don't understand what usg is trying to do with ufw. First, ...
ulearner's user avatar
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697 views

ufw Does Not Block Port for curl

I am trying to block outgoing traffic to port 9200 temporarily. My use case is I want to test what happens when an Elasticsearch cluster (at port 9200) becomes unreachable to my application. I ...
Jacob Quisenberry's user avatar
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Why Can't I access my website ,even if 80 port of my ecs server is open?

os system of ecs server :ubuntu. os of my computer:win10. I deployed my web project to my ecs server. I could access my project online until I installed the ufw on my ecs server. I cofigured the ...
Abner's user avatar
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Can't use Firefox on Ubuntu 22.04.1 LTS on Lenovo ThinkPad T460 after installing and uninstalling Proton VPN

I installed ProtonVPN. It worked for a while with Firefox. Then ProtonVPN started to send "not responding" error messages. Though the internet is fully operational on all other devices, ...
Holly's user avatar
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Questions re ufw settings

I have been running Ubuntu 20.04 desktop since last February, and I configured and enabled ufw at that time. I have questions on the output below. sudo ufw numbered To ...
RTC222's user avatar
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Translate iptables rule to UFW

I need to translate these rules: iptables -A firewall -p udp –dest 239.250.0.0/16 -j ACCEPT iptables -A firewall -p igmp –dest 239.250.0.0/16 -j ACCEPT To UFW rules. Don't know how to set -A -dest -j....
PhönixGeist's user avatar
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607 views

UFW ALLOW rules not working and being ignored

We're setting up some zero trust environments and are needing to block all incoming and outgoing ports, except for allowing the office IP to go in (for administrative purposes), and port 80 and 443 to ...
James Gedny's user avatar
1 vote
1 answer
2k views

Ubuntu server behind a firewall

I have a problem regarding a server behind a firewall, essentially, the whole internet is blocked, and I can't use the "add-apt-repository", problems like "X user or team does not exist&...
Yahya Ahmad's user avatar
1 vote
0 answers
280 views

"Failed to start" notifications when booting into Ubuntu

When attempting to boot I get the following messages: Failed to start Set the console keyboard layout And Failed to start Uncomplicated firewall The screen has remained the same for about 30 minutes ...
Mackenzie Tapp's user avatar
3 votes
1 answer
8k views

22.04 - ufw/ip tables could not fetch rule set

I'm trying to get UFW up and running on a Raspberry Pi 4 running Ubuntu server 22.04. But I am at a loss. # via SSH session: ~$ sudo ufw status ERROR: problem running iptables: iptables v1.8.7 (...
Kcore's user avatar
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How To Permanently keep port 80 open On Ubuntu Server

I just installed Ubuntu Web Server and at the end of the install, it mentioned to me that I could go to IP address. Did that and got the great saying "can't connect". I figure port 80 didn't ...
Dan's user avatar
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Port 9000 Open in FW But Not Showing In NMAP

I am running an Ubuntu 20.0.4 LTS virtual server. I need to be able to access http://localhost:9000/ from within the server for a service I am trying to run, but I keep getting 'Connection refused' ...
jasmines's user avatar
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Ubuntu server 22.04 VM Openvpn connection issues

I'm currently working on a homelab project and built a home server using VMWare ESXI 7. On this Hypervisor i run two ubuntu 22.04 server images, one for file sharing and one to serve as a vpn server. ...
Guillaume Favrot's user avatar
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0 answers
474 views

Cannot access to the remote Linux server after activating firewall

I accidentally log out from my remote Linux ubuntu server after enabling firewall. When I am trying to connect with my SSH it gives me 'port22: operation timed out'. Is there any ways to connect to ...
Kkanybekov Belek's user avatar
1 vote
0 answers
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accepting request to connect on DB port only from a DNS

I'm trying to add an INPUT rule to my server so that only specific address can connect to my DB. So far I tried this iptables -A INPUT -p tcp -m string --string dnsname.com --algo bm --dport 5432 -j ...
El Pandario's user avatar
2 votes
2 answers
524 views

Unexpected entries in firewall log (ufw)

Background I recently installed Ubuntu 22.04 LTS desktop. I left all the default settings untouched during installation, and additionally installed google-chrome and VLC. The machine is behind a ...
Dr Phil's user avatar
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Okay so, I am having trouble connecting to my server from the outside. I disabled firewall, I opened the correct ports, but I still can't get in

I am running Ubuntu Server 22.04 LTS on a Lenovo Thinkpad T460. I am trying to run a minecraft server, so I have the port 25565 open, and it works fine when I join from the local network, but when I ...
feedmepaperr's user avatar
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173 views

Limit maximum incoming connections per IP

I have a server with some code, and for x parallel connections/requests that one IP sends, the server runs x parallel threads (so it runs the code x times in parallel). To put a limit to the currently ...
Edoardo de Pietri Toneli's user avatar
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619 views

can't connect some IP addresses via 'telnet 217.168.180.104 18000' ; telnet: Unable to connect to remote host: Connection refused

I can't connect some IP addresses via 'telnet 217.168.180.104 18000' ; gives below errors: telnet: Unable to connect to remote host: Connection refused..socket connect error. ufw desabled, the ...
nqnr's user avatar
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0 answers
876 views

Not able to load iptables

I am trying install iptables for UFW but having issues with it. Here is how I am installing iptables: agganu@agganuserver:~$ sudo apt-get install iptables Reading package lists... Done Building ...
anugun's user avatar
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Install AAPANEL but the main site doesn't load

I installed aaPanel, but it keeps on timing out. Here's the output: The connection timed out and the CA server was unable to access your website! Verify domain name:hostexodus.co.za Verify URL:Click ...
Nathan Roux's user avatar
2 votes
1 answer
2k views

Ubuntu 22.04 UFW NAT problems

I've done an in-place upgrade from Ubuntu 20.04 to 22.04 and I've found that NAT no longer functions on this firewall box. Before the upgrade, the private network could reach the Internet just fine. I'...
Terry Letsche's user avatar
1 vote
1 answer
3k views

Load iptables rules on boot

I use Ubuntu 20 (server) and I made some iptables rules, but they are not loaded after reboot, so I installed package iptables-persistent, then using iptables-save I saved current rules using command ...
tomsk's user avatar
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Firewall allows only port 22 but I can still curl via http. Need help

I am struggling to get the Ubuntu firewall working as desired. I have set up a Database on an Ubuntu 20.04.3 LTS. I would like to be able to block request such as curl -G --data-urlencode "...
Newskooler's user avatar
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1 answer
5k views

Unable to receive UDP packets

I am trying to send UDP packets from Network Simulator 3 (NS-3) to a Multi-threaded python server(Using UDP socket) but I am unable to receive the packet on the server-side. From the host machine, I ...
Nauman's user avatar
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