Outgoing ports blocked on LXC

[chaosarti]

Hello all,

i am running Proxmox (6.4-8) on Hetzner and installed an LXC (Ubuntu 20.04). I am facing problems with outgoing connections to some ports, for example to port 6000.
Everything is working fine from the pve-host, but it is not working from the LXC.

I tried from LXC:
nc -vz 84.139.123.XXX 6000 nc: connect to 84.139.123.XXX port 6000 (tcp) failed: Connection timed out

nc -vz 84.139.123.XXX 5060 Connection to 84.139.123.XXX 5060 port [tcp/sip] succeeded! nc -vz 84.139.123.XXX 443 Connection to 84.139.123.253 443 port [tcp/https] succeeded!

nmap -p 6000 84.139.123.XXX Starting Nmap 7.80 ( https://nmap.org ) at 2021-07-13 21:04 UTC Nmap scan report for pXXX.dip0.t-ipconnect.de (84.139.123.XXX) Host is up (0.034s latency). PORT STATE SERVICE 6000/tcp filtered X11 Nmap done: 1 IP address (1 host up) scanned in 0.40 seconds

Result from host:
root@pve ~ # nmap -p 6000 84.139.123.XXX Starting Nmap 7.70 ( https://nmap.org ) at 2021-07-13 23:05 CEST Nmap scan report for 84.139.123.XXX Host is up (0.035s latency). PORT STATE SERVICE 6000/tcp open X11 Nmap done: 1 IP address (1 host up) scanned in 17.17 seconds

All Firewalls on any level (datacenter, host, vm) are disabled.

this is my host network configuration:
### Hetzner Online GmbH installimage source /etc/network/interfaces.d/* auto lo iface lo inet loopback auto enp41s0 iface enp41s0 inet static address 65.21.136.XXX netmask 255.255.255.192 gateway 65.21.136.129 # route 65.21.136.128/26 via 65.21.136.129 up route add -net 65.21.136.128 netmask 255.255.255.192 gw 65.21.136.129 dev enp41s0 auto vmbr0 iface vmbr0 inet static address 192.168.188.1 netmask 255.255.255.0 bridge_ports none bridge_stp off bridge_fd 0 post-up echo 1 > /proc/sys/net/ipv4/ip_forward post-up iptables -t nat -A POSTROUTING -s '192.168.188.0/24' -o enp41s0 -j MASQUERADE post-down iptables -t nat -D POSTROUTING -s '192.168.188.0/24' -o enp41s0 -j MASQUERADE post-up iptables -t nat -A PREROUTING -i enp41s0 -p tcp --dport 6001 -j DNAT --to 192.168.188.3:6001 post-down iptables -t nat -D PREROUTING -i enp41s0 -p tcp --dport 6001 -j DNAT --to 192.168.188.3:6001 post-up iptables -t raw -I PREROUTING -i fwbr+ -j CT --zone 1 post-down iptables -t raw -D PREROUTING -i fwbr+ -j CT --zone 1

This is the configuration on my lxc:


Would love to have some feedback, thanks a lot.

 

[oguz]

hi,

that's weird.
maybe you have ufw or similar firewall installed inside your container?

 

[chaosarti]

hi,

that's weird.
maybe you have ufw or similar firewall installed inside your container?

Thanks for the reply. I've restarted whole server and then it was working (strange). Problem solved.