Tag: security

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An easy way to Install OpenVPN in CentOS – snippet

Source: https://zulfah.my/files/openvpnsetup/vpn_install.txt

Got this while surfing the internet. A no brainer way to install and setup OpenVPN in CentOS. The only thing left is to open port 1194/udp 1337/udp from firewall / router

yum update -y && yum -y install nano unzip wget gcc make rpm-build autoconf.noarch zlib-devel pam-devel openssl-devel

cd /home

wget http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm && rpm -Uvh epel-release-6-8.noarch.rpm

yum update -y && yum -y install openvpn

cd /etc/openvpn

wget https://zulfah.my/files/openvpnsetup/configuration-OpenVPN/server.conf.txt

wget https://zulfah.my/files/openvpnsetup/configuration-OpenVPN/easy-rsa-2.2.0_master.tar.gz

mv server.conf.txt server.conf

tar -zxvf easy-rsa-2.2.0_master.tar.gz

cd /etc/openvpn/easy-rsa-2.2.0_master/easy-rsa/2.0

rm -rf vars

rm -rf openssl-1.0.0.cnf

wget https://zulfah.my/files/openvpnsetup/configuration-OpenVPN/easyrsa/vars

wget https://zulfah.my/files/openvpnsetup/configuration-OpenVPN/easyrsa/openssl-1.0.0.cnf

chmod 755 *

source ./vars

./vars

./clean-all

./build-ca
*change hostname

./build-key-server server
*change hostname

./build-dh

cd /etc/openvpn/easy-rsa-2.2.0_master/easy-rsa/2.0/keys

cp dh1024.pem ca.crt server.crt server.key /etc/openvpn

iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE

service iptables save

nano -w /etc/sysctl.conf
*change net.ipv4.ip_forward = 1

sysctl -p

echo 0 > /selinux/enforce

cd /etc/openvpn

wget https://zulfah.my/files/openvpnsetup/configuration-OpenVPN/openvpn-auth-pam.zip

unzip openvpn-auth-pam.zip

service openvpn start

chkconfig openvpn on

useradd testuser -d /dev/null

passwd testuser
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FastSSH.com – free SSH tunnelling account !

FastSSH.com is a provider for FreeSSH account, which can be use for secure tunneling account or to avoid from Firewall.

User has to select SSH account from a set of locations (refer to picture below), which has its own features and limited. (ie: some server offer protocol forwarding in UDP and TCP, while some impose limit on 500 connections/day).

fastssh-selection

Creating an account is as easy as filling the “Account Creation Form”, which does not require email. Account created through FastSSH is valid for SEVEN(7) days.

fastssh-selection-4

However, I personally do not use FastSSH as I’ve my own box, and relying on a 3rd party SSH provider for my tunneling needs would pose security concerns over sensitive data. You’ve been warned.

*FastSSH does not offer UNIX shell, instead it only offers SSH tunneling service. See Simple SSH Tunelling Tips and SSH port forwarding in Microsoft Windows for more information on SSH tunelling

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Simple SSH Tunnelling tips

SSH tunelling is usually used to avoid firewall restriction or to ensure point-to-point encrypted communication.

For example, if you want to send email to smtp server “smtp.yourserver.com” on port 587, but your organization currently blocking smtp port 25 and 587, then you can benefit from SSH tunelling to avoid from being blocked.

To get around that, you need an intermediate server, fastssh.com currently provide SSH tunneling service with 7days trial account.

Simple SSH tunnelling command, if you’re using fastssh.com service.

ssh -f fastssh.com-username@sg.fastssh.com -L 2000:smtp.yourserver.com:587 -N

So in your mail setting, you can safely put, SMTP Server = “127.0.0.1”, SMTP port = “2000” in your setting, in order to automagically connect to “smtp.yourserver.com” port 587 without firewall restriction.

Please refer here, for port forwarding in Microsoft Windows environment using PuTTY

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Stop Comment spams with IP Blacklist Cloud

Comment spams is the bane of any website operator that rely on real human interaction. Stopping comment spams by hand is a tedious process especially when comment spam attacks are sophisticated and are launched from Botnet. There are several techniques that can be employed to fight comment spams including behavioral analysis and also IP analysis.

In maintaining WordPress and Joomla sites, I myself has analyzed several web logfiles and Cloudflare logs to learn that most comment spam originated from certain ip blocks and countries. Therefore, I decided to completely deny access from those affected ip block through firewall (which keep the comment spam low and saves web server resources!)

ipblc_server

However, recently I found a new service IP Blacklist Cloud which list the top most blacklisted ip address through collaborative effort. Normally I find blacklisting by ip address is tedious and probably harmful to legitimate visitors, however after conforming the ip addresses that I found inside my spam logs, I decided the list is legitimate and decided to firewall-block some of the worst offenders in the list.

IP Blacklist Cloud free WordPress plugins, which I personally does not use due to my policy of keeping my installation lean with minimal (to no plugins!), however I see that there’s no harm giving a shot!

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Tips for Securing SSH in Linux Box (Securing SSH Series)

Secured Shell or SSH is a great way to enable a secure login for your UNIX / Linux Box. However there are precaution that you should take in order to properly secure SSH daemon from being scanned or attacked by script kiddies or automated bots.

This week I’m going to write a series of article on securing SSH on Ubuntu Linux Box (VPS) and I’m going to link to this post from time to time.

  1. Disable Root login, enable SSH login for a handful of users only
  2. Install and configure Fail2Ban
  3. Limit access with Firewall Rules (limit by ip block, or ip address)
  4. Limit connection rate to SSH port
  5. Disable keyboard interactive login, Use public-key login
  6. Security Security through obscurity: Hiding SSH version
  7. Security Security through obscurity: Change default SSH ports

Hope this will help in securing your Linux Box / Linux VPS

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BlackBuntu – Ubuntu-flavored Linux Penetration Distro

Blackbuntu is a Ubuntu-based distro used for penetration testing and security auditing. Blackbuntu is designed to be used by students and practitioners who are interested in the field of information security.

Blackbuntu tools are divided into several categories:

  • Information Gathering
  • Network Mapping
  • Vulnerability Identification
  • Penetration
  • Privilege Escalation
  • Radio Network Analysis
  • VoIP Analysis
  • Digital Forensic
  • Reverse Engineering
  • Miscellaneous

Which includes these tools among others: Lanmap2, nmbscan, dnsmap, fierce, hostmap, ltrace, tctrace, sqlbrute, sqlmap,sqlninja, mysqloit, sqlcheck, wfuzz,xsser,xssploit,jmeter, nikto2,skipfish,wbox, autopsy,scalpel,mboxgrep,galetta,afstats, wepcrack,giskismet,fakeap,aircrack-ng,cowpatty,bluebugger,bluescan, bluesnarfer, iwar,protos-sip,sipcrack,brutessh,hydra,sshater

…and many more.

Blackbuntu can be downloaded from its official website – http://www.blackbuntu.com/