Linux command

 


============NETSTAT=============

On .80 machine

tcp6       0      0 10.10.4.80:44016        15.15.0.1:3083          ESTABLISHED

Here local port 10.10.4.80:44016 is connected with remote 15.15.0.1:3083

On .99 machine

tcp6       0      0 15.15.0.1:3083          10.10.4.80:44016        ESTABLISHED

tcp6       0      0 15.15.0.1:3083          :::*                    LISTEN

and is listening from any connection from any ip and port from outside, so its a server socket on .99

===================TCP DUMP================

tcpdump -vv -X -i em3 'port 44016' -w dump.log

========================DF ===================
Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 252G     0  252G   0% /dev
tmpfs                    252G  4.0K  252G   1% /dev/shm
tmpfs                    252G  652M  252G   1% /run
tmpfs                    252G     0  252G   0% /sys/fs/cgroup
/dev/mapper/centos-root  1.8T  4.8G  1.7T   1% /
/dev/loop0               1.9G  6.1M  1.7G   1% /srv/node/swiftloopback
/dev/sda2               1014M  187M  828M  19% /boot
/dev/sda1                200M   12M  189M   6% /boot/efi
tmpfs                     51G     0   51G   0% /run/user/0

Explanation :

devtmpfs                 files system space is accessible via /dev directory in Linux OS .
So if go inside /dev and add some files, those are actually stored in devtmps storage 

Filesystem                           Size  Used Avail Use% Mounted on
/dev/mapper/centos-root  1.8T  4.8G  1.7T   1%   /






 


=============== Mount =====
a device such as HDD/USB is mounted on a directory
















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