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On Mac OS X (10.9) the netstat command in the terminal prints the following. What means *.* in this context? Is this a client or a server socket? How can I find out which process opens this connection(s), and for what reason?
$ netstat -an
Active Internet connections (including servers)
Proto Recv-Q Send-Q Local Adress Foreign Address (state)
[...]
udp4 0 0 *.* *.*
udp46 0 0 *.* *.*
[...]
A *.* in the Local Adress column for UDP means that the socket hasn't been bound to a specific port.
AFAIK such a socket can't really be used for anything.
If you try to use it for receiving, it won't listen to anything. If you try to use it for sending, it will automatically be bound to a port.
So my only conclusion is that they're sockets kept for sending data, but no data has been sent on them yet (since it's the first call to sendto that binds the port).
You can find the process who owns a socket by using lsof. It has a lot of filtering options but I usually find it easier to just just grep, like so:
sudo lsof -n | grep -F "UDP *:*"
The -n turns off dns resolution which otherwise might take quite some time.
Edit: It might also be to call ioctl(..., SIOCGIFMEDIA) or similar to get network interface information.
*:* means any IP address, on any network interface.
To find out which process owns which connection, pass -p to netstat, e.g. netstat -anp. You may need sudo.
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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.
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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."
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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).
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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.
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I don't know if jssh has any security built-in. While testing web apps, I would only like to be able to connect to jssh from localhost. I added the following lines to iptables :
iptables -A INPUT -p tcp -s 0/0 --dport 9997 -j LOG
iptables -A INPUT -p tcp -s 0/0 --dport 9997 -j DROP
will they provide the security I need?
EDIT : this is related to programming. The test is written in ruby . But for the test to work, jssh must be enabled. By default, jssh runs on port 9997 and accepts all incoming connections. Once connected, it accepts commands from the connected user. Imagine the potential harm it could do if someone connects to a jssh shell that's being ran by an user with administrative priviledges .
EDIT2 : Just because I don't have a problem with the code I write, this doesn't mean that this question should be dismissed. I think it's a legitimate question. I would like to know if I have some control over one of the tools I'm using.
Have you tested if the default configuration allows connections from outside localhost?
AFAIK, by default it binds to 127.0.0.1 (only localhost), and not to 0.0.0.0 (all interfaces).
SSH only accepts connections from authenticated users. It is about nothing but security. Your question remains unclear.