Linux:Services

dhcpd

dhclient

# Request an IPv4 adres from a DHCP server
dhclient -4

# Show verbose information when requesting an IPv4 adres from a DHCP server
dhclient -4 -v

Configuration

/etc/dhcp/dhcpd.conf

Basic configuration file

# Set the domain clients should use when resolving hostnames (equivalent to search domain)
option domain-name "brammerloo.nl";

# Set the domain name servers for DHCP clients
option domain-name-servers ns1.brammerloo.nl, 8.8.8.8;

default-lease-time 600;
max-lease-time 7200;
log-facility local7;

# Best practice = define any connected subnets, but don't configure DHCP for them
subnet 192.168.1.0 netmask 255.255.255.0 {
}

# Basic DHCP for a subnet configuration
subnet 192.168.0.0 netmask 255.255.255.0 {
  range 192.168.0.100 192.168.0.150;
  option routers 192.168.0.1;
}

Docker

Checks

# List Docker containers 
docker ps

# List all Docker container IDs
docker ps -aq

# List logs for container 987sdh3qrasdhj
docker logs 987sdh3qrasdhj

# List RAM/CPU usage for Docker container asdlkasd67k
docker stats asdlkasd67k

# Show verbose container information such as commands run, network, ID, etc
docker inspect oiu2398sda87

Commands

# Enter the shell inside a docker container
docker exec -ti a89sd98sa7d /bin/bash

# Execute a command inside a container as a specific user, root in this case
docker exec -it -u root asd87289hasdadz tail /var/log/nginx/access.log
docker exec -u 0 -it as892asnj2as /bin/bash

# Restart docker container yoga
docker restart yoga

# Restart the 3 given containers
docker restart 79f71c7f4d91 bbb3d3f5c3b1 b0a3204d4098

# Start this container
docker start as9823nzxc0

# Stop this container
docker stop as9823nzxc0

# Restart all unhealthy Docker containers
for i in $(docker ps | grep unhealthy | awk '{print $1}'); do docker restart "$i"; done;

PowerDNS

• https://doc.powerdns.com/authoritative/index.html
• https://doc.powerdns.com/authoritative/manpages/pdns_server.1.html
• https://doc.powerdns.com/authoritative/manpages/pdnsutil.1.html

Checks

# List commands
pdns_server --help

# Check config and parse for errors
pdns_server --config=check

# List available commands 
pdnsutil --help

# Check config and parse for errors
pdnsutil --config=check

# List all available zones
pdnsutil list-all-zones

# List all domains in the primary zone
pdnsutil list-all-zones primary

# See zone information for a specific domain
pdnsutil show-zone mydomain.com
pdnsutil show-zone 77.5.10.in-addr.arpa

# Check zone for errors
pdnsutil check-zone mydomain.com

# List all created TSIG keys
pdnsutil list-tsig-keys

Commands

# Activate TSIG key for domain "myexample.com" in the primary zone
pdnsutil " myexample.com transfer primary

MAAS

Checks

Logs in either place:
/var/log/maas/
/var/snap/maas/common/log

# List status of MAAS services
maas status

# List MAAS commands
maas --help

# List available arguments for the init command
maas init --help