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Wed, May 30, 2007 5:39 pm

Checking on Whether a Remote System is an Oracle Server

Nmap can be used to determine if a system is functioning as an Oracle server using the command nmap -p 1521 -P0 -sT <ip_address>. Port 1521 is a port used by Oracle server software, but the port may also be used by other software, so, if nmap reports the system is listening on that port, it does not guarantee that the system is an Oracle server.

The options specified above are as follows:

-p <port ranges>
       This option specifies what ports you want to query.

-P0    Do  not  try  and  ping hosts at all before scanning them.  This
       allows the scanning of  networks  that  don't allow  ICMP  echo
       requests  (or  responses) through their firewall. 

-sT    TCP connect() scan: This is the most basic form of TCP scanning.
       The connect() system call provided by your operating  system  is
       used  to  open  a  connection  to  every interesting port on the
       machine. If the port is listening, connect() will succeed,
       otherwise  the  port  isn't reachable. One strong advantage to this
       technique is that you don/t need  any  special  privileges.  Any
       user on most UNIX boxes is free to use this call.

For a list of other ports used by Oracle, you can check Which TCP/UDP port or ports does 'oracle' use?


  1. Which TCP/UDP port or ports does 'oracle' use?
    SecureTrust TCP/UDP Port Search Lookup Tool

[/network/Internet/IP/ports] permanent link

Sat, Aug 28, 2004 12:32 am

Determining the Country Associated with an IP Address

You can use GeoIP to look up the country associated with a given IP address (you can also give it a hostname to determine the country). To create the GeoIP program geoiplookup, you can download the C source code from You will need a C compiler to compile the code. If you intend to use it on a Linux or Unix system, you will have a C compiler on the system, so just follow the instructions below to create the geoiplookup program or read the INSTALL file that comes with the file you download from the MaxMind website. If you intend to install it on a Windows system, read the READMEwin32.txt file that is in the .gz file you download.

Unzip the downloaded file, extract the contents of the resultant tar file and then change the working directory to the GeoIP directory created from the contents of the tar file.

gunzip GeoIP-1.3.6.tar.gz
tar -xvf GeoIP-1.3.6.tar
cd GeoIP-1.3.6

Then run the configure and make commands (installation instructions are in the INSTALL file created in the GeoIP directory, but are also summarized here).


You can then issue the command make check to run self-tests of the package, but this step isn't required. You should then type make install to install the software.

make test
make install

At this point you won't need the program binaries and other files in the source code directory and they can be removed with make clean. You can also remove the files created by configure by issuing the command make distclean. You can also remove the GeoIP directory and its contents, if you wish, since make install installs the package's files in /usr/local/bin, /usr/local/man, etc.

make clean
make disclean
cd ..
rm -fr GeoIP-1.3.6

When the program is installed, you will have a geoiplookup program in /usr/local/bin. You can use that program to lookup the country associated with an IP address or hostname. The country is based on the registration for the IP address, i.e. particular blocks of IP addresses will be associated with particular countries or at least areas of the world. The company using the IP address may be based in some other country, however. For example:

GeoIP Country Edition: US, United States

The company has their website,, hosted on a server with a US IP address. But if you issue the command whois, you will see the domain name is registered to a company in India (the company provides website design services). So geoiplookup gives you an indication of where a server is likely to be located, but not necessarily the location of a particular company using that server. Companies and individuals may use servers located in other countries.

   K 3/17, DLF Phase II

   Domain Name: EAPPLIQUE.COM

For an example of a lookup for an IP address, here is another example:

GeoIP Country Edition: HK, Hong Kong

[/network/Internet/IP] permanent link

Mon, Apr 19, 2004 3:28 pm

Determining Your IP Address

If you need to determine the IP address systems on the Internet will see as your address, you can go to any of the following sites:
  3. Canadian Web Solutions
  4. (click on the Quick-Find link)

Keep in mind that address is not necessarily the IP address assigned to your computer if you are on a Local Area Network (LAN). If you are behind a firewall or a router performing Network Address Translation (NAT), your locally assigned address may differ from the address websites and other servers on the Internet see as your originating address. If your router is performing NAT, there may be multiple computers behind the router with unique IP addresses, but the router may have ony one outside IP address. The router keeps track of which connections are associated with which inside IP addresses.

You can determine your system's actual address by going to What is my IP Address?. Or if you are using a PC running Windows by getting a command prompt by clicking on Start, Run, and then typing command and hitting enter. Then type ipconfig, which will show you your IP address, your subnet mask, and the default gateway address, which is the address of the system, e.g. a router, that your system would use to gain access to the Internet. On a Linux system, if you are logged on as root, you can type ifconfig -a, then look for the "inet addr" value, which will usually be associated with the eth0 interface. The l0 interface is a "loopback" address of, which is just an address that allows a system to communicate with itself.

[/network/Internet/IP] permanent link

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