Networking
Hostname
Set
sudo hostnamectl set-hostname vm7.orgDomain
View
hostnamectl status
# or
cat /etc/hostname
HTTP protocol
Method role in RESTful APIs
- POST (sometimes PUT) - Create a new resource using the information sent with the request.
- GET - Read an existing resource without modifying it.
- PUT or PATCH (sometimes POST) - Update a resource using the data sent.
- DELETE - Delete a resource.
Sending arguments
GET method
Sent as a query string after ? in the url.
http://example.com/page?parameter=value&also=another
POST/PUT methods
Stored as key-value pairs in the body (not visible in the url).
{ "key": "value" }
IP
Add a route temporarily (until reboot)
ip route add 192.168.2.1/23 via 10.11.12.3
Add an IP address to an interface temporarily (until reboot)
sudo ip address add 192.168.1.1/24 dev eth0
Bring interfaces up and down
sudo ip link set eth0 up
sudo ip link set eth0 down
Delete a route temporarily (until reboot)
sudo ip route delete 192.168.2.1/23 via 10.11.12.3
# or
sudo ip route delete 192.168.2.1/23
Show ARP cache (MAC addresses)
ip -c neighbor show
Show information for all interfaces
ip -c link show
Show ip addresses allocated to interfaces
ip -c address show
Show public ip address
curl ifconfig.me
Show statistics of an interface
ip -c -h -s link show eth0
- Options c and h add color and human-readable values to output.
Route
Add route temporarily (until reboot)
sudo route add -net 192.168.0.0 netmask 255.255.255.0 gw 192.168.0.1
# Add default gateway.
sudo route add default gw 192.168.0.1
Delete route temporarily (until reboot)
sudo route del -net 192.168.0.0 netmask 255.255.255.0
# Delete default gateway.
sudo route del default
Show routing table
route
Ss
Useful options
| Option | Description |
|---|---|
| -4 | IPv4 sockets only. |
| -a | Listening and non-listening sockets (established for TCP). |
| -l | Listening sockets only. |
| -m | Socket memory usage. |
| -n | Don't resolve numeric adresses/ports. |
| -o | Options (i. e. state established). |
| -p | Process using socket. |
| -t | TCP sockets. |
| -u | UDP sockets. |
| -x | Unix domain sockets. |
| -Z | Process and security context (SELinux). |
Traceroute
See route to target host.
traceroute targetHost
To bypass firewalls that block ICMP traffic try options:
--udp
# or
--tcp
Note: These commands were tested on RHEL 7 unless otherwise specified.