ANSWERED Eddie + Kubuntu 24.04 firewall

[raix 1]

Hello All,
I was wondering if anyone has experienced the following setup, issues and could provide me with solution suggestions. 

Goal: having a killswitch by all incoming and outgoing connections blocked by default via firewall (gufw) on Kubuntu 24. Opening Eddie and turning on Network lock which should turn off firewall and open rules needed for vpn connections. All data should go through vpn. In case of Eddie closure or crush, fw turns back on and no data should go out of vpn.

My case: firewall is set to Reject or Ignore for incoming and outgoing communication. Opening Eddie and activating Network lock creates needed rules. However, Eddie is not able to connect to any server. 
Seeing error in this part of a log:
OpenVPN > UDPv4 link local: (not bound)
OpenVPN > UDPv4 link remote: [AF_INET]<IP of server to connect to>:443
OpenVPN > write UDPv4 []: Operation not permitted(fd=7,code=1)
However, if fw is set to allow outgoing, there is "OpenVPN > TLS: Initial packet from..." in this step, connection to vpn server continues with further steps and is successful. 

I have been using the same setup on older version of Linux Mint, firewall set to Deny or Reject for incoming and outgoing, Eddie with Network lock turned on. Eddie can connect to any server without issues.
Is there any rule or setting that needs to be added to Kubuntu/Ubuntu 24 firewall settings in order for Eddie to be able to connect to servers? Any help or suggestions would be much appreciated. Thank you.

[Staff 10697]

@raix

Hello!

Can you print the complete list of rules when Network Lock is enabled? 

Kind regards
 

[raix 1]

Hello, 
please find attached the list. 
Thank you.

iptables-legacy_rules.txt

[Staff 10697]

Hello!

Please publish also a system report generated by Eddie (please do not edit the destination IP address as you did earlier) and also disable gufw completely. Set rules only through iptables-legacy, do not mix with any overlapping frontend during the tests (and do not create your own chains) in order to avoid that gufw custom chains in the filter table interfere. 

Kind regards
 

[raix 1]

Hello, 
please find attached two system reports generated by Eddie:
SysRep-gufwOn.txt - gufw was kept on for this report so that is shows that error I referred to in the first post.
SysRep-gufwOff.txt - this report was generated with gufw disabled and without any manual setup done. Connections worked as expected.

Even though connections work with gufw turned off it does not solve my goal of having a killswitch in cases when Eddie has Network lock disabled or it is not running at all. Is there any recommended setup to achieve this, please? 
Thank you.

SysRep-gufwOff.txt SysRep-gufwOn.txt

[Staff 10697]

6 hours ago, raix said:

Even though connections work with gufw turned off

Hello!

Excellent.

Quote

it does not solve my goal of having a killswitch in cases when Eddie has Network lock disabled or it is not running at all. Is there any recommended setup to achieve this

Yes, but use iptables-legacy (in general, the same frontend used by Eddie too for Network Lock) and not gufw; also do not define custom chains.

Kind regards
 

[raix 1]

Hello, 

3 hours ago, Staff said:

Yes, but use iptables-legacy (in general, the same frontend used by Eddie too for Network Lock) and not gufw; also do not define custom chains.

could you be more specific with iptables-legacy rules needed for a killswitch or direct me, please? I tried to set default INPUT, FORWARD and OUTPUT from accept to drop using iptables-legacy but Eddie won't even open with such settings.
Thank you.

[Staff 10697]

On 9/13/2025 at 9:27 PM, raix said:

Hello, 

could you be more specific with iptables-legacy rules needed for a killswitch or direct me, please? I tried to set default INPUT, FORWARD and OUTPUT from accept to drop using iptables-legacy but Eddie won't even open with such settings.
Thank you.

Hello!

Consider to block any outbound packet except those directed to localhost, local network and those necessary for DHCP. Example (you will need to adjust your local network subnet):

sudo iptables -F OUTPUT
sudo iptables -A OUTPUT -d 127.0.0.1 -j ACCEPT
sudo iptables -A OUTPUT -p udp --dport 67 -j ACCEPT
sudo iptables -A OUTPUT -p udp --dport 68 -j ACCEPT
sudo iptables -A OUTPUT -d 192.168.0.0/16 -j ACCEPT
sudo iptables -A OUTPUT -j DROP

sudo ip6tables -F OUTPUT
sudo ip6tables -A OUTPUT -d ::1 -j ACCEPT
sudo ip6tables -A OUTPUT -p udp --dport 546 -j ACCEPT
sudo ip6tables -A OUTPUT -p udp --dport 547 -j ACCEPT
sudo ip6tables -A OUTPUT -d 2001:db8::/64 -j ACCEPT
sudo ip6tables -A OUTPUT -j DROP

Then you can make the rules persistent (check how to use iptables-save and ip6tables-save).

Kind regards


 

[raix 1]

Thank you, this helped and pointed me to right direction!