Is it possible to check that if the ports are open for the remote system on ubuntu server?
I should able to check if a port(eg:ssh) on my machine is open for the remote machine.
use good old telnet:
[user@lappie ~]$ telnet host 22
Trying ip.adr.tld ...
Connected to host (ip.addr.tld).
Escape character is '^]'.
SSH-2.0-OpenSSH_5.1p1 Debian-5
this is a successful attempt. An unsuccessful one should look like this;
[user@lappie ~]$ telnet host 23
Trying ip.adr.tld ...
telnet: connect to address ip.adr.tld: Connection refused
telnet: Unable to connect to remote host: Connection refused
or with nmap
[user@lappie ~]$ nmap host
Starting Nmap 5.21 ( http://nmap.org ) at 2010-10-07 11:25 CEST
Nmap scan report for host (ip.adr.tld)
Host is up (0.0052s latency).
rDNS record for ip.adr.tld : host.domain.tld
Not shown: 995 closed ports
PORT STATE SERVICE
22/tcp open ssh
80/tcp open http
111/tcp open rpcbind
3000/tcp open ppp
5666/tcp open nrpe
Nmap done: 1 IP address (1 host up) scanned in 0.18 seconds
This is simple as :
nc -zw3 domain.tld 22 && echo "opened" || echo "closed"
-w3
is the timeout
Use NMAP. Example:
nmap example.com
You can use IP address in place of domain name. Here is the full documentation: http://nmap.org/book/man.html
From this StackOverflow answer:
You seem to be looking for a port scanner such as nmap or netcat, both of which are available for Windows, Linux, and Mac OS X.
For example, check for telnet on a known ip:
nmap -A 192.168.0.5/32 -p 23
For example, look for open ports from 20 to 30 on host.example.com:
nc -z host.example.com 20-30
For a script, I use something like the following:
nmap example.com -p 22 -sV --version-all -oG - | grep -iq '22/open'
The return value tells you whether the port is open!
Telnet will only work for TCP services, so if you're trying to see if your DHCP server (UDP/68) is running on a remote machine it won't work. Likewise nmap defaults to only scanning TCP ports.
For UDP ports use:
nmap -sU example.com -p 68
I used following command .It gave output what I wanted.
nmap -A IPAddressOfRemoteSystem -p portNumber
ex : nmap -A 192.168.1.87 -p 8080
(or)
we can check the local ports also
before that first check what are the ports are open/listen mode by using following command.
netstat -ntlp | grep LISTEN
after that
nmap -A localhost -p portNumber
and close any one port for example if mysql is running on 3306 you can stop it by,
sudo service mysql stop
and then,
nmap -A localhost -p 3306
Hope this will helpfull.