≡ Menu

firewall rules

I'm trying to get data (AXFR query) from master tinydns server to secondary DNS server using tcpclient as follows:
tcpclient -v a.ns.example.com 53 axfr-get example.com example.com example.com.tmp

But I'm getting an error which read as follows:

>axfr-get: fatal: unable to parse AXFR results: protocol error

How do I fix this problem?
[click to continue…]

Q. I run both RHEL / CentOS Linux server and by default firewall blocked out everything including telnet / ssh access. How do I allow telnet - port 23 and ssh port 22 thought Linux iptables firewall ?

A.By default firewall rules stored at /etc/sysconfig/iptables location / file under CentOS / RHEL. All you have to do is modify this file to add rules to open port 22 or 23.

Login as the root user.

Open /etc/sysconfig/iptables file, enter:
# vi /etc/sysconfig/iptables
Find line that read as follows:
To open port 22 (ssh), enter (before COMMIT line):

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT

To open port 23 (telnet), enter (before COMMIT line):

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 23 -j ACCEPT

Save and close the file. Restart the firewall:
# /etc/init.d/iptables restart

HowTo Disable The Iptables Firewall in Linux

I need to disable firewall in Linux for testing purpose. I'm using CentOS and RHEL version 4.4 / 5 / 6. How do I disable the firewall in Linux?
[click to continue…]

Q. I'd like to start my Iptables based firewall when my computer comes online so that it get protected from the Internet? I'm using CentOS Linux Server version 4.x.

A. CentOS / RHEL / Fedora Linux has service located at /etc/init.d/iptables to start firewall on boot. All you have to do is type the following command to turn on firewall on boot:
# chkconfig iptables on

Your firewall rules are saved at /etc/sysconfig/iptables files.