Slash notation lookup table

Total-addresses: how many unique addresses can be represented. To determine how many are available to be assigned to devices you need to subtract 2 from the provided number to allow for the ‘network’ and ‘broadcast’ address. A further one of these may need to be assigned to a router. Net bits Subnet mask Total-addresses /20 255.255.240.0 4096 /21…

Tar a folder or entire system through ssh

We all had the problem of needing to backup a folder or an entire system from a machine before decommissioning or as a postfix backup solution only to find tarring aint gonna work cause you have very little space left. Also there are folders you want to avoid tarring since they contain logs or system…