Check DNS propagation worldwide
Service from Constellix: DNS Propagation
linux/
Run Ansible playbook on remote IP address
ansible-playbook my.yml -i 162.55.82.217, -e "ansible_user=root"
The trick is to add , after the IP address
Forward remote port to a local one via SSH tunnel
ssh -L <LOCAL_PORT>:127.0.0.1:<REMOTE_PORT> remote_server
TCP connections to <LOCAL_PORT> will be forwarded to 127.0.0.1:<REMOTE_PORT> on remote host remote_server
Connect dedicated servers with cloud servers in hetzner via vSwitch
Main article is provided by Hetzner team here. This article contains instructions for creating vlan interface in Centos 8 using nmcli.
Assumptions (same us in the main article + listed below):
- VLAN ID is
4001 - parent network interface is
enp195s0
Steps:
- Create new connection:
nmcli connection add type vlan con-name vlan4001 ifname vlan4001 vlan.parent enp195s0 vlan.id 4001
- Configure the connection:
nmcli connection modify vlan4001 802-3-ethernet.mtu 1400
nmcli connection modify vlan4001 ipv4.addresses '10.0.1.2/24'
nmcli connection modify vlan4001 ipv4.gateway '10.0.1.1'
nmcli connection modify vlan4001 ipv4.dns '10.0.0.4' # (optional)
nmcli connection modify vlan4001 ipv4.method manual
nmcli connection modify vlan4001 +ipv4.routes "10.0.0.0/16 10.0.1.1"
- Restart the connection
nmcli connection down vlan4001
nmcli connection up vlan4001
- Verify configuration
# Prints what gateway is used to reach the ip
ip route get 10.0.0.5
# Print all connection information
nmcli connection show vlan4001
# Print routing table
ip r
# Use tui interface for NetworkManager
dnf install NetworkManager-tui
nmtui
Restarting NetworkManager wasn’t enough to apply custom routes. Bring interface up and down
And the link to the great RedHat documentation
netcat example
Listen on specified port:
nc -l -v -k 8888
Connect via netcat:
nc -v google.com 80
Extract and count IP addresses from logs
journalctl -n 1000 | grep -E -o "([0-9]{1,3}[\.]){3}[0-9]{1,3}" | sort | uniq -c
Print repository usage
Print how many packages are installed per repository:
sudo dnf list --installed | grep -E -o "@.*" | sort | uniq -c
Remove host entry from known_hosts file
To remove a host entry from ~/.ssh/known_hosts you can do it manually by editing the file or use ssh-keygen application:
ssh-keygen -R 135.181.157.20
This should fix Host key verification failed error
Clear file from leading new line and etc
cat file | tr -d [$'\t\r\n'] > new_file