about time , ssl and other things …

To see the certification information from linux cli (k is optional for without verification)

curl –vvIk https://<FQDN>or<IP&gt;

To read the certificate file human readable (you can use -inform parameter to change the output format)

openssl x509 -in <your_certificate_file_name_maybe_txt_pem_whatever>

Sometimes you can have broken/corrupted pem or certificate files could be ! maybe wrong copy past , windows to linux copy , ftp copy issues that time using “curl” for only debug could not help pls try more tool to double check for example “wget”

I faced Socket error: [X509] PEM lib (_ssl.c:2751) and couldn’t find any solution and wget helped me, wget show us some of certifications files are not readable.

Another option is using openssl with s_client parameter

openssl s_client -host FQDN -port 443 -quiet

tzdata = time zone database

Sometime people are mixing UTC and GMT , GMT is time zone and UTC is time standard but both of them share same current time practice. No any country or territory use UTC as a local time.

Debian change time zone 

dpkg-reconfigure tzdata

or

sudo cp /usr/share/zoneinfo/xxx/xxx /etc/localtime

About how ntp work , what is stratum, what is reference clock pls check the links below. Generally reference clock is stratum-0 and its atomic time(cesium clock) some more levels there startum-1 , 2 up to 16 and looks like we are querying time from mostly  startum-2 servers.

https://ntpserver.wordpress.com/2008/09/10/ntp-server-stratum-levels-explained/

http://www.ntp.org/ntpfaq/NTP-s-algo.htm

To update time with date command perfect article from nixCraft http://www.cyberciti.biz/faq/howto-set-date-time-from-linux-command-prompt/

I mostly needed this one

date +%T -s “10:13:13”

To password less sudo privileges  

sudo su

echo “noroot ALL=(ALL) NOPASSWD: ALL” >> /etc/sudoers

Posted on 23/08/2016, in Uncategorized and tagged , , , , , . Bookmark the permalink. Leave a comment.

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