#Check ethernet interfaces for discards
[root@emc-01 cme]# ethtool -S eth0
NIC statistics:
     tx_packets: 33861
     rx_packets: 51050
     tx_errors: 0
     rx_errors: 0
     rx_missed: 0
     align_errors: 0
     tx_single_collisions: 0
     tx_multi_collisions: 0
     unicast: 35202
     broadcast: 14175
     multicast: 1673
     tx_aborted: 0
     tx_underrun: 0

#Find file
find / -name <filename>

#Check ethernet interfaces
ifconfig -a

#Check Routing Table
netstat -rn ;

#Check listening ports
netstat -an

#Check free system memory
free

#Additional info about system memory
cat /proc/meminfo

#Monitor system processes & CPU utilization
top

#Check disk partitions and free space
df -k

#Find large files on the disk
find . -size +20000k -exec du -h {} \;

#Find files without "No such file or directory" outputs
find ./ -name "File_name" -type d 2>/dev/null

#Packet Capture based on interface and port - * Use the the –s 1600 option when capturing input.  Required to extract video out of packet capture.
tcpdump -i <interface> -s 1600 -w <filename> port <port_number>

#Packet capture on port range
tcpdump -s 1600 -w <filename> portrange <port_numberstart>-<port_numberstop>

#Packet capture on the output no size option
tcpdump -w <filename> portrange <port_numberstart>-<port_numberstop>

#Packet capture with rotating files with a maximum data for each file (at interface eth0, all packets [-s 0], Of 10 MB each file [-C] 10, up to 50 files [-W 50], on the path/file /tmp/example.pcap. The files will be example.pcap1, example.pcap2, example.pcap3, example.pcap4, etc... 
tcpdump i eth0 -s 0 -C 10 -W 50 -w /tmp/example.pcap

-s 0 tells tcpdump to collect the entire packet contents. 
-vvv enables verbose logging/details (which among other things will give us a running total on how many packets are captured).
-C 100 tells tcpdump to store up to 100 MB of packet data per file.
-W 50 tells tcpdump to store up to 50 rollover files (example.pcap00, example.pcap01 … example.pcap49 at which point it would start over)
-w /tmp/example.pcap tells tcpdump where to write the files. Important note on this: since tcpdump will be creating new files dynamically, this destination directory needs to be an area where it can create new files (for example /tmp).
So in this case, tcpdump will use a max of ~ 5 GB.

#Clear corruption error break on telnet/ssh session

>stty sane

>reset

#Unzip a tar.gz file
tar fzx <filename>