user1097772's questions

I have my own server application in C, I bind my server on localhost address 127.0.0.1 and let it listen in first case on port 10000 and in second case on port 20000. When I run command I lsof | grep IP in last column is: in the first case: localhost:webmin (LISTEN)
and, in the second case: localhost:20000 (LISTEN)

So instead of port 10000 there is webmin. What does it mean? I found this. It says that Webmin is a web-based interface for system administration for Unix but that isn't enough clear explanation. So what webmin exactly mean?

I'm using Ubuntu 11.10. And I want to know something about firewall in Ubuntu, because I want to know if it could be the reason why my application doesn't work properly.

Little background:
I'have programmed client-server application, where Server is in C and client in java, when I run it from Eclipse Indigo (programing editor & environment) it works fine, but when I compile and run the klient in terminal, the communication doesn't work. The server doen't even recognize that the klient try to connect to the server. (using tcp sockets). Somebody said me that firewall could cause these problems, so my question should be probably What effect have firewall to applications and network communication??? (I run all on localhost 127.0.0.1 and port 10000).

It could be little complex question, so I'll try to more spiecify it with few little questions connected to my research and effort to find the source of problem.

This is what I've get when I put in terminal iptables -L:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination        

1) I look at ubuntu wiki and I suppose there should be some rules, so I suppose that the firewall is not configured and it's off. Question: Am I right?
2) If is the firewall off or not configured could it have affect to network communication on my computer? (According the backgroud info)
3) If is the firewall on or bad configured can I do something to set up it correctly or swich off? 4)If I do something from no. 3 will it have bad impact to my security (virus protection on internet)?

NOTE: I have few theoretical info about linux, newtorking, firewalls, but I don't have many experiences with linux configuration and practical using these things.