Netmask Netmask (binary) CIDR Notes ____________________________________________________________________ 255.255.255.255 11111111.11111111.11111111.11111111 /32 Host (single addr) 255.255.255.254 11111111.11111111.11111111.11111110 /31 Unuseable 255.255.255.252 11111111.11111111.11111111.11111100 /30 2 useable 255.255.255.248 11111111.11111111.11111111.11111000 /29 6 useable 255.255.255.240 11111111.11111111.11111111.11110000 /28 14 useable 255.255.255.224 11111111.11111111.11111111.11100000 /27 30 useable 255.255.255.192 11111111.11111111.11111111.11000000 /26 62 useable 255.255.255.128 11111111.11111111.11111111.10000000 /25 126 useable 255.255.255.0 11111111.11111111.11111111.00000000 /24 "Class C" 254 useable Continue reading "CIDR Subnet Mask Cheatsheet"
How to reset root password on Linux server
First we need to boot into recovery mode. To do so, restart server and hold Shift down to call up the boot menu. Then select (recovery mode) for the image you are using. Once you get Recovery menu, select root and press Enter. You will be redirected to recovery console.
root@server1:~#
At this point we need to mount file system, since it is in RO (read-only) mode. To do so, type the following:
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