Ahmed Matar wrote:
>
> I am in urgent need of the port numbers that are usually open on most
> firewalls so that applications can transmit information to users on those
> ports who are behind firewalls.
And the answer is....None! :)
Seriously, every environment is different. There is no list of "usually
open ports" as each environment is only going to open the ports they
specifically need. If you where to look at what ports are "most likely"
to be open in an outbound (from client to external server) they would
be:
HTTP - TCP/80
FTP - TCP/20 & TCP/21 (and/or random high ports for passive FTP)
DNS - UDP/53 & maybe TCP/53
In rarer cases you might see:
SMTP - TCP/25
IMAP - TCP/143
POP - TCP/110
Telnet - TCP/23
With the above said, some environments do allow outbound connections to
be established using just about an IP transport or TCP/UDP port number.
It really depends on the need of the environment as well as the admin
setting up the firewall.
> As far as I know (correct me if I am wrong),
> but most firewalls (e.g. Microsoft Proxy 2.0)
<GRIN>
On this list you may get an argument about whether MSP2 is even
considered to be a firewall. ;)
> The reason I'm asking
> this question is because I am creating a application that plays streamed
> audio transmitted to it from another application running on a remote
> webserver.
One point of advice if I may, initialize the connection from the
application running on the client. Do not try to initialize it from the
server. The reason is that you at least have a chance of the firewall
allowing outbound connections from the client to the server on the port
number you choose. Your chances are pretty close to zip that the
firewall will allow connections to be established from an external
server to internal clients. If this is allowed, you might as well not
even have the firewall.
> I want users behind firewalls to be able to use my application so
> I need to know on what ports I can transmit my audio to the user (via UDP)
> so that if he/she is behind a firewall, the audio will be received.
Check this out:
ftp://ftp.isi.edu/in-notes/iana/assignments/port-numbers
This is the list of well known service ports. Anyone creating an IP
application is suppose to:
A) Use an existing port if the service is already registered
B) Register the port they wish to use
With regards to "A":
grep audio port-numbers
audionews 114/tcp Audio News Multicast
audionews 114/udp Audio News Multicast
audio-activmail 1397/tcp Audio Active Mail
audio-activmail 1397/udp Audio Active Mail
proshareaudio 5713/tcp proshare conf audio
proshareaudio 5713/udp proshare conf audio
You may want to check out each of the above to see if the functionality
matches what you are trying to achieve. Easier than writing your own
protocol. ;)
HTH,
Chris
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