To create zip archives with maximum compression, using the command line use following syntax:
zip archive.zip -9 *.txt
The command above will create an archive named archive.zip add all text files in current directory to the archive, and compress the archive using the maximal available compression, this is done using the integer -9.
The maximum compression option -9 also attempts compression on all files regardless of extension.
Internet connected services, like SSH, receive nowadays a lot of bogus connections. Without restricting access to the server, the it will loose performance due to the amount of authentication and authorization requests sent from the internet. Without certain amount of SSH restrictions connecting abusers will use all locally assigned or available resources to get access to host, in worst case this kind of brute-force might go on for days, weeks, months and eventually the attackers might get access to the host.
There are 2 ways to define the type of access allowed to the service, it applies to many other services as well:
- Usage of internal openssh service settings, f.e.: specifying configuration options, f.e. Port 4711
- Usage of external tools, external to openssh, and any other service, f.e.: iproute2 or sshguard or iptables
Below a list of techniques to minimise the risk of abuse of the SSH service: