Tutorials

Prevent SSH Brute Force Attack with Denyhosts on FreeBSD

Sometime our machine get error about error login from log message on SSHD services. Maybe, our machine has been attached by someone with brute force SSH method. We can use firewall to prevent SSH brute force attack, or we can use sshguard, sshdfilter, or denyhosts to block brute force. This tools will block SSH brute force attack automatically. In here, I will use denyhosts to prevent SSH brute force on my machine.

SNMPD error, libperl.so not found

After doing the update freebsd, snpmd failed to load.
/libexec/ld-elf.so.1: Shared object "libperl.so" not found, required by "libnetsnmphelpers.so.20"

FreeBSD can not find the file "libperl.so". To overcome this can be done as follows:

HardDisk Capacity Monitoring with MRTG

At times, our lack of attention to what is the amount of disk usage is used by our server. Based on experience, a lot of admin Diskspace ignored this problem. Usually the only monitor traffic in and out that could be "captured" through the existing Ethernet. And if you note, actually we really need information about how the rest of our hard disk capacity, or how much is already in use. Monitoring capacity is necessary if we are using the machines we make, requires hard drive capacity is not to run out. For example for a proxy server, database server, and so on.

Blocking Internet Explorer 6 with Squid

Did you know that today, many websites that began eliminating compatibility with Internet Explorer 6 browser. Internet Explorer 6 has 119 bugs. For that of the sysadmin side to minimize grievances or complaints from customers is "Suggest to Upgrade to Internet Explorer Internet Explorer 7 or Internet Explorer 8 or to other browsers like Firefox, Opera, or Google Chrome".

Setting Up no-password SSH

Sometime we had a script for running process in remote machine. In this case, we need to setup SSH with no-password to remote another machine and run process what we need.
The basic idea is, however, that in the cryptosystem that ssh uses (RSA or/and DSA) the encription and decription are done using diferent keys
Basically, what the user (client) needs is to generate a public/private key pair. The server will know the public key, but only the client will know the private key.

Monitoring DNS Server

Short for Domain Name System (or Service or Server), an Internet service that translates domain names into IP addresses. Because domain names are alphabetic, they're easier to remember. The Internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address.

Monitoring Squid with MRTG

If you want to know utilization or performance your Squid Proxy, you can use MRTG to monitoring Squid Proxy. This can do, because Squid Proxy support SNMP and you must configure squid with SNMP support.

Setting Up Squid on FreeBSD

Squid is web caching and conserving badwidth application. With Squid, we will reduce the traffic 30% or more from normal usage (without squid) and enhance respone time. In here, i will use squid 2.7.STABLE3.

Installing Squid.
You can download Squid from here. After you download the source of squid, then :

# tar zxvf squid-2.7.STABLE3.tar.gz
# cd  squid-2.7.STABLE3
# ./configure '--sysconfdir=/etc/squid' '--enable-storeio=diskd,ufs,aufs' '--enable-delay-pools' \
'--enable-pf-transparent' '--enable-ipf-transparent' '--disable-ident-lookups' \
'--enable-removal-policies'
# make
# make install

Step By Step FreeBSD as Internet Server

Installing FreeBSD

1. 1. Select Region.
   2. Select Standart Installation.
   3. Use all drive for FreeBSD.
   4. Create Disklabel, on my installation use 80GB of harddisk, and here my disk label
      • / 512MB
      • swap 1GB
      • /tmp 1GB
      • /usr 4GB
      • /var 2GB
      • /home 1GB
      • /cache (all the rest off harddisk space).
   Read more... Comments (1)

Load Balancing on MikroTik

Quick Start for Impatient Configuration export from the gateway router:

/ ip address add address=192.168.0.1/24 network=192.168.0.0 broadcast=192.168.0.255 \
interface=Local comment="" disabled=no

add address=10.111.0.2/24 network=10.111.0.0 broadcast=10.111.0.255 \
interface=wlan2 comment="" disabled=no

add address=10.112.0.2/24 network=10.112.0.0 broadcast=10.112.0.255 \
interface=wlan1 comment="" disabled=no