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    Firewall Configuration in Linux in Centos 6.2

    IT Discussion
    centos iptables linux unix netstat centos 6
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    • T
      thanksajdotcom @Lakshmana
      last edited by

      @Lakshmana said:

      @thanksajdotcom Sorry dont get angry.The server is web server.SMTP,SNMP,POP3,IMAP needs tp be open

      Ok, I'm not angry, but I'm frustrated. What you just gave us was useful. However, we asked several times for the info and you kept not giving it to us. If it's a language barrier, I'm sorry but I was being as simple and plain as possible.

      SNMP = 161
      SMTP = 25 (unsecured), 465 (secured), 587 (secured)
      POP3, = 110 (unsecured), 995 (secured)
      IMAP = 143 (unsecured), 993 (secured)

      Unless you've blocked them in IPTables already, they should be open.

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      • S
        scottalanmiller
        last edited by

        CentOS does have a tool for adding ports, but other than pointing you to the tool, it doesn't really let us help you. It's not terribly hard to use, but doing an IPTables edit allows us to completely make the change for you. One of the beauties of text configuration files is that we can completely do the fix, not just tell you where to look.

        But if you want to try the TUI, here is the link...

        system-config-firewall-tui
        
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          Lakshmana @scottalanmiller
          last edited by

          @scottalanmiller Ok Scott.I have not noted the things properly so only the confusion came here.Sorry to one and all

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          • S
            scottalanmiller @thanksajdotcom
            last edited by

            @thanksajdotcom said:

            @Lakshmana said:

            @thanksajdotcom Sorry dont get angry.The server is web server.SMTP,SNMP,POP3,IMAP needs tp be open

            Ok, I'm not angry, but I'm frustrated. What you just gave us was useful. However, we asked several times for the info and you kept not giving it to us. If it's a language barrier, I'm sorry but I was being as simple and plain as possible.

            SNMP = 161
            SMTP = 25 (unsecured), 465 (secured), 587 (secured)
            POP3, = 110 (unsecured), 995 (secured)
            IMAP = 143 (unsecured), 993 (secured)

            Unless you've blocked them in IPTables already, they should be open.

            They are all blocked by default. Only SSH and ICMP are open by default on CentOS. RHEL / CentOS is secure by default.

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              thanksajdotcom
              last edited by

              If you're SSHing into the box, run

              cat /etc/sysconfig/iptables
              

              Highlight the output in whatever client you're using to SSH, likely PuTTY, and paste it here. Please. We can't help you without that info.

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              • S
                scottalanmiller
                last edited by

                Here is the only thing that I could find for a firewall block diagram. Definitely not useful for anyone working with firewalls.

                http://creately.com/diagram/example/hb7hjlii3/firewall

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                  thanksajdotcom @scottalanmiller
                  last edited by

                  @scottalanmiller said:

                  @thanksajdotcom said:

                  @Lakshmana said:

                  @thanksajdotcom Sorry dont get angry.The server is web server.SMTP,SNMP,POP3,IMAP needs tp be open

                  Ok, I'm not angry, but I'm frustrated. What you just gave us was useful. However, we asked several times for the info and you kept not giving it to us. If it's a language barrier, I'm sorry but I was being as simple and plain as possible.

                  SNMP = 161
                  SMTP = 25 (unsecured), 465 (secured), 587 (secured)
                  POP3, = 110 (unsecured), 995 (secured)
                  IMAP = 143 (unsecured), 993 (secured)

                  Unless you've blocked them in IPTables already, they should be open.

                  They are all blocked by default. Only SSH and ICMP are open by default on CentOS. RHEL / CentOS is secure by default.

                  Ok, my mistake. Well, those are the ports. Given the info, I'd doubt they are using TLS or SSL, so probably 25 and 143. No reason to use POP3. Avoid it like the plague.

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                    Lakshmana @thanksajdotcom
                    last edited by

                    @thanksajdotcom OK AJ.Thank u.I will configure the things tommorow at my office,

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                    • ?
                      A Former User
                      last edited by

                      Keep in mind order of the rules matters. a Reject before a Accept may render the Accept useless. However in some cases a reject before a accept can be needed.

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                        thanksajdotcom @A Former User
                        last edited by

                        @thecreativeone91 said:

                        Keep in mind order of the rules matters. a Reject before a Accept may render the Accept useless. However in some cases a reject before a accept can be needed.

                        Ditto this.

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                        • S
                          scottalanmiller @A Former User
                          last edited by

                          @thecreativeone91 said:

                          Keep in mind order of the rules matters. a Reject before a Accept may render the Accept useless. However in some cases a reject before a accept can be needed.

                          Yes, don't edit the IPTables file without us. Just provide it and let us edit it for you.

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                            Lakshmana @A Former User
                            last edited by

                            @thecreativeone91 said:

                            ject before a Accept may render the Accept useless. However in some cases a reject before a accept can be needed.

                            Ok If I have any i will contact you

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                              Lakshmana @scottalanmiller
                              last edited by

                              @scottalanmiller Whether a firewall can have IP address of Gateway.Whether it is possible to have?

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                              • ?
                                A Former User @Lakshmana
                                last edited by

                                @Lakshmana said:

                                @scottalanmiller Whether a firewall can have IP address of Gateway.Whether it is possible to have?

                                What are you asking? I'm not sure.

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                                • S
                                  scottalanmiller @Lakshmana
                                  last edited by

                                  @Lakshmana said:

                                  @scottalanmiller Whether a firewall can have IP address of Gateway.Whether it is possible to have?

                                  No, firewalls are like filters. They have no concept of gateways or routes.

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                                    Lakshmana @scottalanmiller
                                    last edited by

                                    @scottalanmiller Ok I am having the WAN network as 192.168.1.0/24 and firewall in betwwen the LAN connection.What is the IP needs to be given to Firewall?

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                                      scottalanmiller
                                      last edited by

                                      I don't understand. The firewall on Linux has no IP address or anything like that. Have you switched from talking about Linux to something completely different?

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                                        Lakshmana @scottalanmiller
                                        last edited by

                                        @scottalanmiller No I am talking about only in linux firewall

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                                        • S
                                          scottalanmiller @Lakshmana
                                          last edited by

                                          @Lakshmana said:

                                          @scottalanmiller No I am talking about only in linux firewall

                                          Then there is no need to talk IP addresses. Ports are all that you need to know.

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                                            Lakshmana @scottalanmiller
                                            last edited by

                                            @scottalanmiller
                                            I have to assign IP for the VM machines I going to install.The requirements are 512 MB RAM,10 GB Hard disk and Centos minimal desktop.I have to use 3 NIC.That is One NIC for allowing WAN,one NIC for LAN and other for my VMmachine

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