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Old 04-03-2003, 01:34 AM   #1
lho
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How do I know if it is my iSP blocking port 25 or my RH8 Firewall setting


I am having problems with port 25.

NMAP shows port 25 is open when I scan localhost
NMAP shows port 25 is close when I scan my public ip 216.232.47.51

FTP, HTTP, SSH, POP3 and IMAP is open

I tried setting the redhat-config-securitylevel however the secrity level always showing high on the graphical UI? I have tried to set it to none or medium then go back to UI and still the same. Restarting the server does not work.

Here are the IMAP scans:

Interesting ports on sony1 (127.0.0.1):
(The 1592 ports scanned but not shown below are in state: closed)
Port State Service
21/tcp open ftp
22/tcp open ssh
25/tcp open smtp
80/tcp open http
106/tcp open pop3pw
110/tcp open pop-3
143/tcp open imap2
443/tcp open https
6000/tcp open X11

Interesting ports on sony1.28c.net (216.232.47.51):
(The 1593 ports scanned but not shown below are in state: closed)
Port State Service
21/tcp open ftp
22/tcp open ssh
80/tcp open http
106/tcp open pop3pw
110/tcp open pop-3
143/tcp open imap2
443/tcp open https
6000/tcp open X11

Thanks
Lawrence
 
Old 04-03-2003, 01:52 AM   #2
lho
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Still new to Linux. Tried shutting down IPTABLES but port 25 still closed
 
Old 04-03-2003, 07:13 AM   #3
unSpawn
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Post your iptables firewall rules, it's under /etc/sysconfig, and we'll see, ok.
 
Old 04-03-2003, 04:37 PM   #4
lho
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Which file in /etc/sysconfig do you need? There are no files starting with ip*. As far as I know firewall is not running.


[root@sony1 init.d]# ./iptables status
Table: filter
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
[root@sony1 init.d]# ./ipchains status
bash: ./ipchains: No such file or directory

Last edited by lho; 04-03-2003 at 04:55 PM.
 
Old 04-03-2003, 05:03 PM   #5
unSpawn
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As far as I know firewall is not running.
Any box connected to a network should have a firewall running, especiall a public one. Please see the 1st thread in this forum, 2nd post for firewall HOWTO's, scripts etc.
 
Old 04-03-2003, 05:19 PM   #6
lho
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It was hook up to the DMZ zone of the Sonicwall Firewall but I was trying to trouble shoot the port 25 problem. That why it is wide open.

I will take a look at your posts.. Thanks
 
Old 04-04-2003, 04:13 PM   #7
maxspeed
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if you want to know if its blocked by your isp you might just give them a call and ask them. Or just disable your firewall or flush all its rules(iptables -F) and run nmap again, if the port is still blocked is most likely that your isp has it blocked. I still think that the easiest way to find out is to call your isp and ask.Most isp's do block port 25 to prevent spam.
 
Old 04-04-2003, 05:48 PM   #8
lho
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I have confirmed that ISP is not blocking any port. I also tried moving the server back into LAN and tried to telnet into linux box from another machine at port 25, however it is still unsucessful.

This server is a new install. Firewall is not running.
 
Old 04-05-2003, 01:36 AM   #9
maxspeed
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you might want to double check that since i have noticed that some isp representatives don't actually know if they are blocking ports. My isp use to be verizon dsl and they block ports 25 and 80 so i called them up to ask why, the rep told me and explaine why(mostly because of spam and virus). I got disconnected so i called again and another rep answered and he told me they didnt block any ports.
 
Old 04-11-2003, 01:51 AM   #10
RCampbell5
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Check your /var/log/maillog file for any errors or hints. run netstat -a and look for the smtp entry. It should be in listening to smtp port (25). Mine looks like this:

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State

tcp 0 0 *:smtp *:* LISTEN

Roger.
 
Old 04-11-2003, 12:14 PM   #11
lho
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I have found out there is a configuration item in /etc/mail/sendmail.mc that said to only listen to 127.0.0.1 (localhost). It shouldn't have been there, but it was.

Everything is working now. Thanks
 
  


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