Archive for October 4, 2015

Linux how to modify the default port number of SSH?

By tort ( October 4, 2015 at pm 11:04) · Filed under Linux Share

In the installed linux，By default ssh is open，Vulnerable to hacker attacks，simple，Effective action is to modify one of the default port number
Such as the following，We modify my 22 2501
It is to modify / etc / ssh / sshd_config // note，Easy and ssh_config mixed
step one
[root@localhost ssh]# more sshd_config
# $OpenBSD: sshd_config,v 1.69 2004/05/23 23:59:53 dtucker Exp $
# This is the sshd server system-wide configuration file. See
# sshd_config(5) for more information.
# This sshd was compiled with PATH=/usr/local/bin:/bin:/usr/bin
# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented. Uncommented options change a
# default value.
#Port 22 //Comment out the first 22
port 2501 //Add a new port
#Protocol 2,1
Step Two
[root@localhost ~]# service sshd restart
Stopping sshd:[ OK ]
Starting sshd:[ OK ]
Step Three
Testing with SecureCRT

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Linux Firewall Configuration，Open port 80、3306port

By tort ( October 4, 2015 at pm 11:03) · Filed under Linux Share

vi /etc/sysconfig/iptables

-A INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT (allow 80 port through the firewall)
-A INPUT -m state –state NEW -m tcp -p tcp –dport 3306 -j ACCEPT (allow port 3306 through the firewall)
Special Note：Many users add these two rules to the last line of firewall configuration，Cause the firewall fails to start，Right should be added to the default port 22. This rule below
After adding a good firewall rules are as follows：

######################################
# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state –state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state –state NEW -m tcp -p tcp –dport 22 -j ACCEPT
-A INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT
-A INPUT -m state –state NEW -m tcp -p tcp –dport 3306 -j ACCEPT
-A INPUT -j REJECT –reject-with icmp-host-prohibited
-A FORWARD -j REJECT –reject-with icmp-host-prohibited
COMMIT
#####################################

/etc/init.d/iptables restart
#Finally, reboot the firewall configuration to take effect

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