how do i know if port 21 is open? (proFTP question)

sirpelidor · 02-12-2004, 04:03 AM

hihi, trying to setup proFtp here, but it seems won't let me log in (kept saying severshut down)
i'm suspecting if it has to do with port 21 not aviable. are there's way to check?

here's the msg in detail:

root@localhost init.d]# ./proftpd start
Starting proftpd: [ OK ]
[root@localhost init.d]#

then i use client...
[allen@localhost allen]$ ftp xx.xx.xxx.xx
Connected to xx.xx.xxx.xx.
500 FTP server shut down (going down at Wed Feb 11 22:54:13 2004) -- please try again later
ftp>

so... i'm not sure if it has to do with port 21 or what not, thanks for your advise

dennisa · 02-12-2004, 04:39 AM

you can use netstat to see what services are listening to which port

Code:

netstat -a | grep LISTEN | grep ^tcp

should show something like

Code:

tcp        0      0 *:ftp                   *:*                     LISTEN

you may want to use a port scanner like nmap to see if it works. double checking your configuration might be a good idea as well

/ Dennis

VincentB · 02-12-2004, 06:04 AM

You should really try nmap.
But check if you are behind a firewall.
For example, here are two different results for the same machine. The first test, I use my local IP adress while on the other one I use the IP provided by the ISP.
Hope this help,
Vincent

Starting nmap 3.30 ( http://www.insecure.org/nmap/ ) at 2004-02-12 12:59 UTC
Interesting ports on sun.xxx.be (192.168.1.100):
(The 1627 ports scanned but not shown below are in state: closed)
Port State Service
22/tcp open ssh
23/tcp open telnet
53/tcp open domain
80/tcp open http
111/tcp open sunrpc
139/tcp open netbios-ssn
443/tcp open https
631/tcp open ipp
665/tcp open unknown
668/tcp open unknown
683/tcp open unknown
694/tcp open unknown
787/tcp open unknown
2049/tcp open nfs
3306/tcp open mysql
6000/tcp open X11
10000/tcp open snet-sensor-mgmt

Nmap run completed -- 1 IP address (1 host up) scanned in 0.436 seconds
[vincent@sun vincent]$ nmap 80.201.XX.221

Starting nmap 3.30 ( http://www.insecure.org/nmap/ ) at 2004-02-12 13:01 UTC
Interesting ports on 221.XX-201-80.adsl.skynet.be (80.201.XX.221):
(The 1643 ports scanned but not shown below are in state: filtered)
Port State Service
80/tcp open http

Nmap run completed -- 1 IP address (1 host up) scanned in 71.450 seconds
[vincent@sun vincent]$

thanks for your question, btw: I did not know that port 80 was open on my computer.

Regards,
Vincent