Subnet to Mask Bits conversion table Mask CIDR Length (Mask Bits) 128.0.0.0 1 192.0.0.0 2 224.0.0.0 3 240.0.0.0 4 248.0.0.0 5 252.0.0.0 6 254.0.0.0 7 255.0.0.0 8 255.128.0.0 9 255.192.0.0 10 255.224.0.0 11 255.240.0.0 12 255.248.0.0 13 255.252.0.0 14 255.254.0.0…
Category: Networking
Verify the speed of my Network Cards in Linux
How to tell the network speed of network cards in Linux? CentOS 7 Find the network cards: ip addr 1: lo: mtu 65536 qdisc noqueue state UNKNOWN qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever…
Show List Of Network Cards in Linux
How do I display a list of all network cards under Linux operating systems? You can use any one of the following command to list network cards installed under Linux operating systems. Please note that the ifconfig and ip commands…
What is the use of /etc/udev/rules.d/70-persistent-net.rules file in Rhel/Centos?
what is the use of /etc/udev/rules.d/70-persistent-net.rules file in linux? is anyother way to change interface name in linux other than 70-persistent-net.rules? This file associates your NIC’s MAC address with an interface name that will be given to the NIC at…
Neighbor table overflow Error in Linux
The ‘neighbor table overflow’ is a VERY common linux issue on large networks. Some network trigger this with default linux settings (because the previous network regime put so many IP address subnets on a single vlan , it creates large…
Add private IP to Debian Ubuntu for R1
Add the IP as Eth0 when the primary is Eth1 (no gateway) # nano /etc/network/interfaces auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 10.168.19.36 netmask 255.255.255.224 hwaddress 0C:C4:7A:6A:0F:E4 auto eth1 iface eth1 inet static address…
Nmap
See if ports are open nmap -T4 -Pn -p 21,22,25,80,110,143,443,3389 $SERVER_IP
Test server download speeds
Server connections speeds are a function of a variety of variables. The server’s connection speed to the Internet, all processes that are simultaneously trying to connect (uploads and downloads share the total speed available), the overall health of the Internet…
The Difference between a Megabyte (MB) and a Megabit (Mb)
Do you think 1 Megabit per second (1 Mbps) will allow you to download a 1 Megabyte file in one second? This is not the case. A Megabit is 1/8 as big as a Megabyte. 1 Megabyte = 8 Megabits…
Netstat Commands for DDoS Checking
Useful commands to check if a server is getting ddos’d Show IPs with more than 10 connections open: # netstat -nat | grep “:80” | awk -F: ‘{print $8}’ | sort | uniq -c | sort -n | awk ‘{…