Point to alternative ports?

[CidneyX]

Is it possible to direct connections to specific ports?

For example:

alternativewebserver.mysite.org would connect to port 81 instead of 80?

Or secondarySMTP.mysite.org could direct connections to port 26 where a secondary SMTP engine was listening?

Is this possible with DNS, and if so, how?

 

[ChrisAC]

DNS is used for name resolution. It has nothing to do with port numbers!

Chris.


**********************
Chris Andrew, CCNA, CCSA
chris@iproute.co.uk
**********************

 

[8humhum8]

yes it is - if ur using win 2k, go to an IIS management tool like in
Start -> Programs -> Administrative Tools -> Internet Services Manager. there, in the left pane, under Internet Information Services, expand the computer name on which the site is hosted. right click on the site name, and Properties. in the Web Site tab, or FTP Site tab (depends on the site protocol) change the value in TCP Port. this will change the default port through which the site is accesed.

if you only want to connect once through a different port, in the adress bar use the following format:

Protocol://hostnameort/

for example,

http://www.google.com:8080

to connect to google through port 8080.

 

[CidneyX]

OK,

So this isn't really a DNS issue. 8humhum8's solution doesn't rely on DNS, but it serves as a good starting point, and illustrates that standard traffic can be delivered through alternative ports.

I understand that http travels on port 80. Is it too much to ask that it be possible to have choice1.mysite.org and choice2.mysite.org arrive at separate listening ports (ex. choice1 being port 80 and choice2 being port 81)? Is there a way to cause port redirection based on names? I don't think this is technically impossible. Perhaps it would involve firewall/port redirection based on name resolution. Is there a custom or proprietary solution that has been invented that can address this situation? I am thinking something like Fpipe that can integrate name resolution. Am I talking gibberish here?

 

[ChrisAC]

8humhum8,

The question was "Is this possible with DNS, and if so, how?"

Since when was IIS a DNS server?

Yes, you can always change the port number that servers listen on. You just can't use DNS to direct to a port. DNS just resolves names. If a mail server looks up an MX record then the DNS servers just says, 'you need to send that to mail.domain.com at 111.222.333.444'. It doesn't say 'oh by the way, use port 25'. The application knows that mail uses port 25 and so will attempt a connection on that port.

Chris.


**********************
Chris Andrew, CCNA, CCSA
chris@iproute.co.uk
**********************

 

[8humhum8]

yes iproute, you are right. my mistake.

but on the other hand, can't you lease multiple domain names for the same IP? and use different ports? i mean, you arent expected to register several static IP's (if such thing is possible, for one connection) if you host multiple sites on one server.

according to what you say,

"If a mail server looks up an MX record then the DNS servers just says, 'you need to send that to mail.domain.com at 111.222.333.444'. It doesn't say 'oh by the way, use port 25'."

what if multiple smtp sites are hosted on 111.222.333.444? then u cant use port 25 for all of them can you? if i am wrong, then please correct me.

 

[danielhozac]

You can host several domains on the same server, though with certain protocols you wouldn't be able to tell which domain the connection concerns. Sendmail, for instance, allows for virtual users, and Apache allows for virtual hosting. They both rely on the specifics of the protocols they serve.

//Daniel

 

[ChrisAC]

Plenty of mail servers host mail for multiple domains and all of them use port 25 for SMTP, for that is the port that SMTP uses.

Same thing for web sites. As danielhozac has said, Apache allows for virtual hosting. A typical example of this would be if your ISP gives it's uses web space. Each user doesn't get a server each do they? They use virtual servers, all running on the same port.

I think that you need a better understanding of how DNS, mail and web services work. The ports used are determined by standards, servers and client applications. DNS is just for name resolution.

Chris.


**********************
Chris Andrew, CCNA, CCSA
chris@iproute.co.uk
**********************