SRE – Systems and Network

Here is a simple script with configuration file to generate a self-generated SSL certificate (cert/key pair). First define a config file openssl.cnf containing the certificate informations: [ req ] default_bits = 2048 encrypt_key = yes distinguished_name = req_dn x509_extensions =…

You can get standard information about the certificate directly by opening a connection to a website: openssl s_client -showcerts -connect python.org:443 </dev/null Answer will be like: CONNECTED(00000003) depth=3 C = SE, O = AddTrust AB, OU = AddTrust External TTP…

You already probably noticed that if you want to update the ownership of a symbolic link on any UNIX system, a simple chown won’t do the job. Indeed, let’s suppose you have this: 8 lrwxr-xr-x 1 user1 group1 4 Jun…

There is no easy way to remove a list of mails in queue with a same sender or domain in Postfix. But you can use some standard commands to get this working. First check the list of mails you want…

It is possible to modify a partition size on EXT filesystem thanks to some few commands. We will take here a simple example: We have a /dev/sda5 partition mounted on /home Its size is currently 150G and we want to reduce it to 100G Let’s check…

If you forgot what iLO IP has been defined on your linux server and you are working remotely on it, don’t worry, you can still retrieve it with a common tool called ipmitool – available on most of the distros with…

Stuck with a telnet session that refuses to give you hand back on console? No worries… You just have to know the correct command to sort this out! When you are opening a telnet connection, you probably got something like:…

When you are using the history command on a UNIX system, by default, you’re only getting an action list with numbers but no date and/or time to complete this history. For that, you have to define an environment variable HISTTIMEFORMAT that will describe how…

Let’s imagine that we have the following directory listing: $ ls -ls /data/db1/ total 4778688 1488 -rw-r–r– 1 dbmaster 760264 Feb 14 00:20 database_2016_file1 496 -rw-r–r– 1 dbmaster 251529 Dec 29 12:45 database_2016_file2 808960 -rw-r–r– 1 dbmaster 414187520 Jan 30…