Well Known TCP/IP (Reserved) Ports

In TCP/IP and UDP networks, a port is an endpoint to a logical connection and the way a client program specifies a specific server program on a computer in a network. Some ports have numbers that are pre-assigned to them by the IANA, and these are called the “wellknown ports” which are specified in RFC 1700.

Port numbers range from 0 to 65536, but only ports numbers 0 to 1024 are reserved for privileged services and designated as wellknown ports. This list of wellknown port numbers specifies the port used by the server process as its contact port.

Note: Important ones are highlighted in bold.

Port Number Description
1 TCP Port Service Multiplexer (TCPMUX)
5 Remote Job Entry (RJE)
18 Message Send Protocol (MSP)
20 FTP Data
21 FTP Control
22 SSH Remote Login Protocol
23 Telnet
25 Simple Mail Transfer Protocol
37 Time
42 Host Name Server (Nameserv)
43 WhoIs
49 Login Host Protocol (Login)
53 Domain Name System (DNS)
69 Trivial File Transfer Protocol (TFTP)
70 Gopher Services
79 Finger
103 Standard
108 SNA Gateway Access Server
109 POP2
110 POP3
115 Simple File Transfer Protocol (SFTP)
118 SQL Services
119 Newsgroup (NNTP)
137 NetBIOS Name Service
139 NetBIOS Datagram Service
143 Interim Mail Access Protocol (IMAP)
150 NetBIOS Session Service
156 SQL Server
161 SNMP
179 Border Gateway Protocol (BGP)
190 Gateway Access Control Protocol (GACP)
194 Internet Relay Chat (IRC)
197 Directory Location Service (DLS)
389 Lightweight Directory Access Protocol (LDAP)
396 Novell Netware over IP
444 Simple Network Paging Protocol (SNPP)
445 Microsoft-DS
458 Apple QuickTime
546 DHCP Client
547 DHCP Server
569 MSN
1080 Socks

@Courtesy: http://www.webopedia.com/quick_ref/portnumbers.asp

Happy Learning !!!


How to kill tomcat server?

This is the similar way to kill any responsive or unresponsive server/executable.


Step 1)

ps -awwef | grep tomcat

This gets the process identifier aka pid (3rd from the list when you run the command)

Step 2)

sudo kill -15 <pid>

Kills the given process


Step 1)

netstat -o -n -a | findstr 8080

Step 2)

taskkill /F /PID 4184


UNIX/DOS Commands that I often use…

Command Description
sudo dscl . list /Users uid Lists all the users ids
sudo dscl . list groups gid Lists all the group ids
id -u
id -u RakeshChouhan
Gives the UID (user id) of username RakeshChouhan — Output is 502
nl Gives the number of lines the file has.
export Used to Set Environmental variables
sudo Execute a command as another user
sudo -i OR sudo sh Log in as root
exit switch back to RakeshChouhan
ssh-keygen -R localhost Removes latest added ssh key and retains the old one.
ssh localhost Shows the last ssh login
ssh-keygen -t rsa -P “” Generates a SSH key (id_rsa.pub)
sudo chmod 700 /etc/ssh_host_dsa_key Changing permissions to ssh_host_dsa_key
cat $HOME/.ssh/id_rsa.pub >> $HOME/.ssh/authorized_keys copies the generated id_rsa.pub to authorized_keys in .ssh folder
cp copies a file from source and pastes in the destination folder.
ln -s Sets the link for the given fileName to the destination folder where the given
filename exists
ps aux | less Shows all current running process ids, with % of memory usage
ps Shows all current running process ids at current instance
ps -ef Shows all running process and as well monitor and refreshes the result in each
lsof Shows all processes and PID’s
mkdir Creates a directory for the given name.
kill 12345 Kills the process id
jps Shows all current running Java Processes
man Shows the manual page that you want to see
echo $JAVA_HOME Shows the current mapped JAVA_HOME environment variable
echo $HADOOP_HOME Shows the current mapped HADOOP_HOME environmental variable
echo $PATH Shows the system PATH variable
clear clears the current working terminal screen
java -version Gives the java version
hadoop version Gives the Hadoop Version
pwd Shows the current working directory
exit Ends the Terminal’s process
find -f macos Finds the file named macos in the HardDisk
find . -type d | grep {directoryName}
find / -name {directoryName} -type d
Finds the directory named {directoryName} in the HardDisk
rm -R -i Removes/Deletes each file and each sub directory from the given directory Name
with a prompt for each file and sub directory
rm -rf Removes/Deletes all files and sub directories without a prompt.
rmdir Deletes the given directory
ls Lists out the Non hidden files and directories in the current folder
ls -a Lists out all the hidden and non hidden files and directories in the current
ls -l Lists out all non hidden files and folders alphabetically, and shows the file
and directory permissions,user,created date.
ls -help Lists out all the non hidden files and folders with more details (Users,
Groups, Access levels)
ls -l file.txt; echo $? Check if the file.txt is present or not in a particular directory.
wc Displays the Counts of lines, words, bytes in this order for the given
cd Change Directory
cd ~ Go to previous directory
du -sh | grep G Determines the Disk Usage in GB.
tar -xvfz Un-tars filename
vi Opens file with vi editor tool.
jar -cvf WAR_NAME.war * Creates a war for the given folder (Note that you should be in that folder for
that folder to be war)
grep ‘{WORD_TO_FIND}’ ‘{IN_FILE}’ Searches a text in the file. Ex: grep boo /etc/passwd. See grep for more
grep {GREP_OPTIONS} ‘{WORD_TO_FIND}’ ‘{IN_FILE}’ Searches a text in the file. If using grep option

a). -A 10
Displays 10 more lines after (from the line where the text was found).
Ex: grep -A 10 boo /etc/passwd.

b). -B 10
Displays 10 more lines before (from the line where the text was found).
Ex: grep -B 10 boo /etc/passwd.

c). -C 10
Displays 10 more lines before and after (from the line where the text was found).
Ex: grep -C 10 boo /etc/passwd.

See grep for more options.

what is Gives What is What. What Does What ????
touch Creates a text file
cat > {fileName} Creates a fileName and opens it for edit/writing. “control + z” saves the file
and returns.
mv Moves a file from Source location and drops in destination location
rmr Removes the mentioned file from the destination location
ifconfig Gives the ip, mac addresses
netstat Gives the network status
netstat – a | grep “10123” Determines which remote hosts are connecting to your host on a particular port
say 10123
nslookup Determines your hostname and IP and viceversa
uptime Determines from how many days your server is up
stat Displays the fileName attributes/properties
sudo -s launchctl load -w /System/Library/LaunchDaemons/ftp.plist Loads FTP Server
sudo -s launchctl unload -w /System/Library/LaunchDaemons/ftp.plist UnLoads FTP Server
sudo apachectl start Starts MacOSX default Apache Server
sudo apachectl stop Stops MacOSX default Apache Server
sudo apachectl restart ReStarts MacOSX default Apache Server
httpd -v Gives the current Apache version
head -5


Prints/Displays the first 5 lines of file test.txt
sed ‘5,$d’ test.txt Prints/Displays the first 4 lines of file test.txt — sed is the text editor
same as vi editor.
tail -5


Prints/Displays the last 5 lines of file test.txt
sed -n ‘$p’ test.txt Prints/Displays the last 4 lines of file test.txt — sed is the text editor
same as vi editor.
head -5
test.txt | tail -1
Displays/Prints the 5th line from file test.txt
sed -n ‘4
p’ test
Displays/Prints the 5th line from file test.txt using sed editor
grep -c “Unix” Counts the number of times the word ‘Unix’ occurs in the given file
sed s/Unix/UNIX/g Replaces the word containing ‘Unix’ with ‘UNIX for the given filename
cut -f3 Gives only phone numbers, if my filename has tab separated Name, Address and
Phone numbers.
awk -f3 Gives only phone numbers, if my filename has tab separated Name, Address and
Phone numbers.
exit -1 Logout and Fail a Shell Script programatically.
chown Change file owner to the given userName of a given filePath
chgrp Change file groupName for the given fileName
sudo chattr +i/-i Change advanced file attributes.
/usr/sbin/system_profiler SPHardwareDataType | grep Memory Shows RAM memory (16GB)
df -h Determines how much space is left in current drive. Determines Configured SWAP
space. Swap files are created in (/private/var/vm) directory.
uname -p or arch Displays the processor type. (Current Processor architecture type is i386)
uname -a Displays the type of OS running on top of UNIX. (Here Darwin)
sw_vers Shows the Operating Systems version.
gcc -v Determines whether the required version of gcc is installed
ping or telnet Determines if a remote host is alive or not
top Determines which process is taking how much CPU
telnet hostname port Check if a particular process is listening on a particular port on remote
sudo scutil –set HostName rakeshchouhan.com Sets the hostname (HostName is case sensitive)
hostname Gives you the hostname (case-sensitive). This is the same command in Windows. Also, you can “echo %COMPUTER_NAME%” in Windows to get the hostname.
sudo lsof -i -P | grep 8001 gives the process id of the application which is using port 8001 (PID is 3rd
from the left)
unzip -t file.zip Determines if a Zip file is corrupted.
unzip -j file.zip Unzips a Zip file.
echo “unix” | rev Reverses a string. From unix to xinu
echo “C for Cat” | rev | cut -f1 -d’ ‘ | rev Gets the last word from a line in Unix file. Explanation: The entire line is
reversed (taC rof C), then we cut the first word, we get (taC) and reverse it again.
sysctl -n machdep.cpu.brand_string Gives Processor information
ex: Intel(R) Core(TM) i7-3820QM CPU @ 2.70GHz
system_profiler Gives all the information related to PC (Camera, Bluetooth, Processor, Memory,
Wireless, etc..)
sytem_profiler SPHardwareDataType Gives Hardware Overview Informations.
sysctl -a | grep machdep.cpu Gives all CPU related information
find / -name .DS_Store -delete This deletes all .DS_Store files from all folders of MAC OSX file system.
curl -O
Downloads apache-maven-3.1.1-src.tar.gz
sudo ln -s /Library/Java/JavaVirtualMachines/jdk1.7.0_45.jdk
Set a different Java Virtual Machine
sudo apachectl start Starts apache2 server (verify http://localhost)
sudo apachectl stop Stops apache2 server
brew update Use brew to install packages. This command updates brew formulae’s
brew install {packageName} Installs brew packages. Ex: brew install apache-spark
watch -n1 ls Watches the folder every one second. This is useful to keep a continuous watch on any folder, instead of typing ls -l on the folder every time. In order to watch for every 5 seconds for a given folder, use “watch -n5 ls”
Note that ‘watch’ command isn’t available implicitly. So we need to brew it before.
Ex: brew install watch