Checking Open Ports on a Remote Computer using PortQry

Some rights reserved by Ryan Franklin

 Today for one of the projects the SFTP connection kept failing for some reason. The user-id password used for connecting to the host was correct the hostname was as well correct. There was no way to find out what went wrong. Thankfully command-line gives a good log to verify what goes wrong.

I tried connecting to the SFTP host with various tools like FileZilla, WinSCP but could not get good enough logs. Finally i tried connecting the server using ssh on command-line using my Ubuntu machine. The connection used to time out. That is what i see in the logs as well. I assumed that probably the SFTP port number 22 was closed for the host.

I googled for if i could find a tool to check if a particular port on a machine is accessible or not. I finally found something called as PortQry taht could be used on Windows machine using Commandline.

Its a very small 140 KB command-line based software tool that you can use to check if a port on some machine is accessible or not.

After using this tool i got to know that the machine had a Firewall  kind of protection which wasn't allowing me to access the SFTP port on it.

Here's how you PortQry on Windows:

• Download the software using the link : http://www.microsoft.com/en-in/download/details.aspx?id=17148

• Double click an unzip the files to any location say C:/

• Hit Windows+R in the run box enter "cmd"

• Go to the directory where the PortQry was extracted.

• Execute the program PortQry by entering PortQry<enter>

• This will display a list of help information and the correct usage of the command

The following is the syntax to check the port status :
portqry -n myhostname.net -e 80

PortQry can inform the status of a port as "Listening", "Not Listening", or "Filtered"
Listening : There is some service active on that port
Not Listening : Port is closed
Filtered : No response, Presumably its behind some kind of firewall.

Syntax
portqry -n name_to_query [-p protocol] [-e || -r || -o endpoint(s)]

Common command line switches:
-n : IP address or name of system to query
-p : TCP or UDP or BOTH (default is TCP)
-e : single port to query (valid range: 1-65535)
-r : range of ports to query (start:end)

For single port use
portqry -n 127.0.0.1 -e 80

For a Range of ports, use the -r switch:
portqry -n 127.0.0.1 -r 80:85

Note:
- PortQry also displays extended information for known services, such as SMTP, POP3, IMAP4, FTP, and is capable of performing LDAP queries.
- A GUI based alternative is also available now called PortQryUI

Sample Output:
C:\PortQryV2>portqry -n 127.0.0.1 -e 40
Querying target system called:
 127.0.0.1
Attempting to resolve name to IP address...
Name resolved to xx.xx.xx.xx
querying...
TCP port 22 (ssh service): FILTERED

C:\PortQryV2>portqry -n 127.0.0.1 -e 80
Querying target system called:
 127.0.0.1
Attempting to resolve IP address to a name...
IP address resolved to xx.xx.xx.xx
querying...
TCP port 80 (http service): LISTENING

C:\PortQryV2>portqry -n 127.0.0.1 -e 22
Querying target system called:
 127.0.0.1
Attempting to resolve IP address to a name...
IP address resolved to xx.xx.xx.xx
querying...
TCP port 22 (ssh service): NOT LISTENING