How do I open a port in Linux CentOS 5 for an Informix server ?

in /etc/services I added the service and put in there the port number. Is there any other changes that I should make ?

When I do telnet destionationhost 1526 from a windows machine it tells me that could not open connection to the host on that port. Connect failed.

I know that if a port is open, I should be able to connect with telnet.

My firewall is disabled (policy accept from all - input output, forward, etc all chains)

iptables -A INPUT -i eth0 -p udp --sport 1526 -m state --state ESTABLISHED -j ACCEPT

and -p tcp

iptables -A INPUT -p udp --dport 1526 -j ACCEPT

and -p tcp


still... those commands are useless since the firewall is off by default, did iptables -F in rc.local so everytime when the machine restarts the firewall is "disabled" I mean it accepts all connections.

One more thing, I know that linux boxes have the se linux thing. I remember that when I installed the se linux was disabled, but still... where do I need to disable that if it's enable ? And how do I test it ?


netstat -nap | grep :1526
tcp 0 0 127.0.0.1:1526 0.0.0.0:* LISTEN 7128/oninit

to disable selinux you need to modify /etc/selinux/config with the following line "SELINUX=disabled"

Can you ping your destinationhost from the windows machine or SSH from there?

Ofc I can connect to SSH and to ping it. The firewall like I said it's "disabled". I mean it accepts all the connections.

Ok, just as I thought, that selinux was enabled

in selinux/config I had the line
SELINUX=enforcing

now I modify it to disabled

did restart (reboot) and it's still now working. I remember that one month ago when the CentOS 5 and the informix wasn't reinstalled it worked fine.

Let me reformulate. I had the same configuration (I gues) one month ago. Now I have reinstalled the CentOS and informix server and I can't longer connect to the 1526 port using telnet.

Anyway, it was a good one with that selinux to be disabled. Thankx. Any other suggestions, please ?

Can you telnet localhost 1526 from your CentOS mahcine?

What do you mean by this? Do you mean you were running CentOS 5, informaix was NOT installed, and telnet <destinationhost> 1526 worked for you?

Sorry, was having trouble with the quote function.

centos82 read carefull all what I said. I said that one month ago I had the same configuration, informix server installed and centos installed, now I have reinstalled CentOS and informix server and now the telnet dosen't work on 1526port.

http://www.idevelopment.info/data/Un...TPAsRoot.shtml

I did what they said there, I can connect to telnet as root and use the telnet as a ssh *(putty)
If I telnet from a windows machine to the ip of the server and port 22 it lets me in so it's just fine but dosen't let me connect on port 1526.

Can you telnet localhost 1526 from your centos server?

Yes, I saw that question, didn't answer 'cause I was in other tests.
Yes, it worked.

Connection closed by foreign host.
[root@xxxx ~]# telnet localhost 1526
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
now I pressed enter
Connection closed by foreign host.
[root@xxxx ~]#


It seems that I can connect but only from localhost. What seems to be the problem then ?

One more thing. I am with the windows machine in a domain and the CentOS server dosen't have a DNS name associated in the domain controller. Thing is, I don't remember but I think that one month ago it wasn't the Centos server associated with a dns in the domain controller so I think this isn't the problem but I t hough that I should let you know.

The windows machine is 172.16.12.x and the Centos is 172.16.100.x

If I ping it it replys me, so it's ok.

I installed mysql-server for a test. I successfully connected to port 3306 via telnet.

You have an interesting problem. You can connect locally, you can connect to other ports remotely.

What does iptables -L show you?

How many NICs are configured on your CentOS machine?

What does "cat /etc/services |grep 1526" show?

Then "lsof |grep <first 4 character of port listed for 1526"

ex.

(root@ctrl)
[/root]$ cat /etc/services |grep 1526
pdap-np 1526/tcp # Prospero Data Access Prot non-priv
pdap-np 1526/udp # Prospero Data Access Prot non-priv

(root@ctrl)
[/root]$ lsof |grep pdap


I've got nothing running on 1526 so nothing returns from lsof but you should get something if its running.

Ok, so let's recapitulate:

I have CentOS 5 X86_64 and Informix server 9.40 UC2

1. I can ping the linux machine from the windows machine.
2. I can connect to port 22 using telnet.
3. I can connect to port 3306 *(mysqlserver) from the localhost linux machine server.

[root@xxxx ~]# telnet localhost 3306
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
4
5.0.45!{n4V4B/,b"~w[@l$jma~quit
Bad handshakeConnection closed by foreign host.
[root@xxxx ~]#

4. I can connect to port 3306 *(mysqlserver) from a windows machine using telnet.
5. The iptables are default policy set to accept. Anyway I have added the exception for the port 1526 tcp and udp, just to be done.
6. I have disabled the SE linux enforcing.
7. I can connect to port 1526 to the linux machine but only from the localhost - using root.


[root@xxxx ~]# telnet localhost 1526
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
quit
Connection closed by foreign host.
[root@xxxx ~]#


Dear centos82,

I said I have the policy of iptables (chains) set to accept as default. Did iptables -F and put the exception iptables command for the port 1526, but I'm sure I didn't have to do that. Anyway, here's the output log:


[root@xxxx ~]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT udp -- anywhere anywhere udp dptdap-np
ACCEPT tcp -- anywhere anywhere tcp dptnserv
ACCEPT udp -- anywhere anywhere udp sptdap-np sta te ESTABLISHED
ACCEPT tcp -- anywhere anywhere tcp sptnserv stat e ESTABLISHED

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Chain RH-Firewall-1-INPUT (0 references)
target prot opt source destination
[root@xxxx ~]#

And you are very right I can connect to 1526 from localhost but can't connect from a remote windows machine.

According to your 1st post
which means its only listening on localhost ie 127.0.0.1.
You probably need to change Informix cfg to listen on the relevant IP.

[root@xxxx ~]# cat /etc/services |grep 1526
onserv 1526/tcp #Pt informix server
pdap-np 1526/tcp # Prospero Data Access Prot non-priv
pdap-np 1526/udp # Prospero Data Access Prot non-priv
[root@xxxx ~]#



=====================================================================



[root@xxxx ~]# lsof |grep onserv
oninit 6321 informix 5u IPv4 20644 TCP herculetestnserv (LISTEN)
[root@xxxx ~]#

damn smiley )

[root@xxxx ~]# lsof |grep onserv
oninit 6321 informix 5u IPv4 20644 TCP herculetest: onserv (LISTEN)
[root@xxxx ~]#