Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about programming within the scope defined in the help center.
Closed 9 years ago.
Improve this question
Why is 22 the default port number for SFTP? Is there any specific reason for this?
It's the default SSH port and SFTP is usually carried over an SSH tunnel.
Why is 21 the default port for FTP? Or 80 the default for HTTP? It is a convention.
From Wikipedia:
Applications implementing common
services often use specifically
reserved, well-known port numbers for
receiving service requests from client
hosts. This process is known as
listening and involves the receipt of
a request on the well-known port and
reestablishing one-to-one
server-client communications on
another private port, so that other
clients may also contact the
well-known service port. The
well-known ports are defined by
convention overseen by the Internet
Assigned Numbers Authority (IANA).
Source
So as others mentioned, it's a convention.
Not authoritative, but interesting: 21 is FTP, 23 is telnet. 22 is SSH...something in between (that can take the place of both).
Ahem, because 22 is the port number for ssh and has been for ages?
Related
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 5 years ago.
Improve this question
I have a dlink router..Dlink DIR 600M...I am trying to port forward 1337 and 1334 through my router and opened listener but after enable i checked canyouseeme.org but theres no port opened..i have a cable net connection...my wan ip and public ip is different.
If your WAN IP address and your Public IP addresses are different, you will need to be sure that you first port forward from the public-facing router to your D-Link router. If you do not have access to your public facing router (as is the case with my current network setup), then this port forwarding is not possible.
I have a DIR-651, and there are check boxes next to all the Port Forwarding rules. Make sure those are checked. I've wasted hours of troubleshooting because one of the boxes wasn't checked and saved.
Finally, make sure that you have a server running on the correct IP address and port that you specified on your router. Also, make sure that your firewall is disabled on those ports. If your server isn't configured to respond on those ports, then canyouseeme.org will not respond that those ports are open.
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 8 years ago.
Improve this question
Do I need to forward these ports? Is there a way to do it on Windows 7? I've tried using a program named smart port forwarding but it crashes when the program is running. Thanks in advance.
You shouldn't need to forward those ports in order to be able to run the applications. Chrome and Steam are connecting through those ports to the internet because they are ones that the operating system says are available for outgoing connections and provided them with that unique port number when each application asked for it.
These applications should all run fine for you, without needing to open any ports. Opening a port is most always to let incoming traffic be accepted, not for outgoing traffic to be stopped. A telltale sign that a port is not open is that no connection can be made. If you tried to connect over the internet (port 80) to most random IP addresses, you won't be able to find anything, because the device at that IP address rejected your attempt to open that port to them. So because you are (I am assuming) able to successfully run both Chrome and Steam and have them be able to connect to the internet, you shouldn't be facing a port forwarding issue. The port numbers are just assigned essentially at random each time that an application needs to open an outgoing socket. (this being a simplification of the whole paradigm, but hopefully enough to be able to answer this question).
Edit: And yes, like #Rumesh-Eranga pointed out as well, port forwarding is done at the router level (on the internet router itself) and not at the computer level. It's a way of saying to the router "alright, any time this network receives a request to open port XYZ, send it to this computer that is connected to our local network."
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 8 years ago.
Improve this question
How can I add a port to 127.0.0.1? I have 127.0.0.1:5984 open but want to open another one. Any idea? As A head's up I'm new to computers. I'm on a Mac running OS X Mavericks. I'm also on Xfinity.
Edit: I am having a port conflict while attempting to use CouchDB, how can I resolve this?
A port is a listener for a specific protocol such as tcp or udp. In order to open a port. You need a program or service to listen on that port. For example, by default Skype will listen on port 80.
Please read the wikipedia page for a basic overview or what a port is.
In computer networking, a port is an application-specific or
process-specific software construct serving as a communications
endpoint in a computer's host operating system. A port is associated
with an IP address of the host, as well as the type of protocol used
for communication.
http://en.wikipedia.org/wiki/TCP_Port
Edit: To answer actual question:
Unavailable Port
Problem
$ couchdb Apache CouchDB 0.9.0a747640 (LogLevel=info) is
starting. Failure to start Mochiweb: eaddrinuse {"init terminating in
do_boot",{{badmatch,{error,shutdown}},[{couch_server_sup,start_server,1},{erl_eval,do_apply,5},{erl_eval,exprs,5},{init,start_it,1},{init,start_em,1}]}}
Solution
Edit your /etc/couchdb/couch.ini file and change the Port setting to
an available port.
Excerpt from:
http://wiki.apache.org/couchdb/Error_messages
You can change the port CouchDB listens on by editing its local.ini file (which is in /usr/local/etc/couchdb by default). Under the httpd section, uncomment the port entry and change its value to the port you want to listen on (5983 in your example).
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 4 years ago.
Improve this question
I could not make the telnet port command execute.
I did what was told in this link.
the snapshots of my cmd are:
what else shall i do to execute these commands?
The telnet command connects to the host you specify as the first argument on the port you specify as the second argument (or 23, if you only specify a single argument).
When you tried to execute telnet port, it tried to connect to the server port on port 23. Since there is no server with the address port (unless you specified it in your pc's hosts file), telnet couldn't connect to it.
I'm guessing the second command failed, because www.udacity.com doesn't accept connections on port 8080 (the second argument of the command).
I don't see any instructions in the link you provided.
EDIT: If you're trying to connect to localhost, use telnet localhost (to connect to port 23) or telnet localhost <port> (replace <port> with the port you are trying to connect to).
I also faced same problem. Solution, after adding feature for telnet server, a new service is added for this but is in by default disabled state. So make sure service is running and in non disable mode.
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 7 years ago.
Improve this question
I'm writing a windows service which will expose an http RESTful web service for other processes on the machine. This will be deployed to lots of machines on various corporate desktops that I have little/no control over. How should I choose which port my service should listen on?
I'll make it configurable, but need to know how to choose some reasonable default(s).
fyi I'm planning on using .NET 3.5 (unable to use 4.0 for deployment reasons) and WCF with WCF REST Starter Toolkit.
UPDATE: to clarify, these are corporate non-development machines. I want to choose a port that's not likely to be used for anything else. I guess from this list of PORT NUMBERS (thanks #Pascal Thivent) that I should choose one in the dynamic/private range
The Dynamic and/or Private Ports are those from 49152 through 65535
So is there any better way of choosing a port within that range, or do I just choose randomly?
The official assignments registred with the Internet Assigned Numbers Authority (IANA) for HTTP are:
80: standard port for HTTP,
8080: HTTP alternate (commonly used by cache or proxy or web server running as a non-root user)
The ports below are non official ports (not registered with IANA) that are also used:
8081: HTTP alternate
8090: HTTP alternate (used as an alternative to port 8080)
I don't know what kind of machines you are targeting but if they include development machines, I would probably use 8090 to minimize possible conflicts.
References
PORT NUMBERS
List of TCP and UDP port numbers
Ultimately we chose an arbitrary unused port in the Registered Port range - from 1024 through 49151 - and then made it configurable on the offchance someone comes along and uses that port for something else. Best solution would then be to register that port.
We chose not to use a dynamic port as processes are able to arbitrarily start using them, so it'd be less consistent whether the port was available.
If your service is HTTP then you should use port 80 - the standard HTTP port. This is typical of most REST webservices.