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Old 06-03-2002, 05:57 PM   #1
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ipchains & blocked ports?

Hello, I have RH 7.3, and I have a cable modem to connect to the internet...

I has a name pointing address which is

I put this in my /etc/hosts file with alias of jasonhbishop

I want to setup a mail server (pop3 & to receive) and also an ftp and telnet server.

I can telnet & ftp to my machine (from my machine) but if I try to telnet to this computer from another system.. it just sits there... (it doesn't say connection refused) but like this: trying 209.128.xx.xx

RH comes with ipchains etc. when I run setup from the prompt, and select firewall configuration, and select mediuk with customization of allow incoming smtp, telnet, ftp , ssh etc. It still doesn't let me into my computer through telnet or ftp, (but I can ssh) which I don't want to use (I know ssh is better but...)

Can anyone help me? Why can't I connect to my machine from a different machine on the internet?

Old 06-03-2002, 06:50 PM   #2
Registered: May 2002
Location: Toronto, ON, Canada
Distribution: Ubuntu, Debian, RedHat/CentOS
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Check your syslog messages somewhere in /var/log and see why these connections are being refused. Also check the logs of the servers (in the same directory) to which you attempted to connect. See if they at least register a connection attempt. If they do, the log will contain a hint as to what the problem is, if they don't, then the ports are probably blocked by your firewall.

To check your firewall rules, disable and enable your firewall type (respectively, listed in the same order) the following:


service ipchains status
service ipchains stop
service ipchains start
For an experiment's sake, it would prpbably be useful to try these connections when your firewall is disabled, to see if it's the cause of your connectivity problems.
Old 06-03-2002, 07:59 PM   #3
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I tried turning off the firewall by type service ipchains stop, and tried telnetting to my machine from another computer on the internet, and it still wouldn't work... (there's also nothing in /var/log/messages about it)

I did see something though, when i typed service ipchains status, it say that, Accept -->all> (for source & destination)and n/a for the ports, but ride underneath it, it says, REJECT tcp -y---- * -> 0:1023

what is the y option?
does this mean that any outside connection is rejected for ports 1-1023?

This is why I can't ftp and telnet right? because there ports are 21 and 23 right?
but why can I ssh to the computer from a outside source? is it's port higher then 1023 by default?
Old 06-03-2002, 08:43 PM   #4
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I tried running the telnet service manually, but typing in.telnetd -debug 1023 (on port 1023) and ran telnet 1023 from the other computer on the internet, and it worked...
so I said that the ports needed to be changed so I edited /etc/services, but then when i tried to telnet from my machine to the other computer or any computer (from my computer) it just says connection refused! I changed the services file back the way it was, but in the ipchains list (ipchains --list) it still says something about the port changes I made in services , eventhough I changed them back to their default values!? what can I do now? all I want to do is to send/receive mail, ftp and telnet to my machine from other computers on the internet...


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