Tags » SysAdmin

Receiving and parsing DMARC reports on main and secondary mail servers

DMARC is made so aggregated reports will be sent by others servers to yours in order for you to find out if some spam source are trying to impersonate your domains. 628 more words

Sysadmin

In The Beginning......

I started working as a Sysadmin by mistake a couple of years ago. At the time we had a “Technical Manager” at the company who had bluffed his way into the job and had no idea how to administer our systems, I had been at the company for many years in different roles so had the advantage of understanding how most things worked. 668 more words

MCSE

Cron jobs

Cron jobs are perfect for executing a specific task or script at a scheduled time or different time periods.

Cron jobs can be run hourly, daily, weekly and monthly. 234 more words

Fedora

Quick count of email request in mailq

A quick way to count how many emails are in mailq:

mailq | grep -c "^"
Linux

Linux Server under DDOS Attack

To find out what IP is causing the DDOS, we can run the next command:

tail -n 10000 logfile.log | cut -f 1 -d ' ' | sort | uniq -c | sort -nr | more
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Linux

Block IP using iptables

In order to block an IP in our Linux server, we need to use iptables:

iptables -A INPUT -s IP-TO-BLOCK -j DROP
service iptables save
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Linux