UNIX Blog

Sh3lls.net A True IRC UNIX Shell Hosting Provider

funtoosh — Wed, 31 Dec 2008 06:13:43 +0000

Just came across this True IRC UNIX shell hosting provider Sh3lls.net. Sh3lls.net is the world’s largest irc shell hosting provider. They even offer services like unix irc shell account, bnc shells, ircd shells, shoutcast hosting, cpanel based web hosting, vpn hosting, proxy hosting, ddos protected vps, ddos protected dedicated servers and lot more.

They are one of the best irc shell provide i’ve ever came across. They offer very very cheap shells but without sacrificing on the quailtiy. They have servers with uptime of over 3 years, which is very hard to achive and shows their ability to maintain their servers and even shows that they really offer quality services.Uptime of their shell servers can be viewed at www.sh3lls.net/uptime.htm

they accept credit card, paypal, liberty reserve, webmoney, western union, wire transfer, cash, money order and also have special arrangements for collecting cash payment from gulf countries as well.

The uptime of their servers even proves that they are not overloading their servers or overselling, so we highly recommend to get your irc shell accounts, bnc shells, ircd shell accounts, shoutcast hosting, irc hosting, vps hosting, web hosting, dedicated servers from Sh3lls.net

And last but not the least they have developed a client software not offered by any other shell provider in the whole world which makes your bnc or eggdrop installation a breeze, you can get their client software from www.sh3lls.net/download.htm

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Filtering mac address using IPTables in Linux

funtoosh — Tue, 12 Jun 2007 11:31:21 +0000

A mac address is acronym for media access control address, is a unique address assigned to almost all-networking hardware such as Ethernet cards, router etc

If you want to filter packets on the basis of mac address, it is possible on linux with iptables.

Iptables comes with MAC module. this matches packets traveling through the firewall based on their MAC (Ethernet hardware) address. It offers good protection against malicious users who spoof or change their IP address. Remember that mac filtering only makes sense for packets coming from an Ethernet device and entering the chains:

1. PREROUTING
2. FORWARD
3. INPUT

iptables blocking with mac address
Drop all connection coming from mac address 00:0F:EA:91:04:08 (add command to your firewall script)

iptables -A INPUT -m mac –mac-source 00:0F:EA:91:04:08 -j DROP

iptables allowing with mac address
Allow port 22 for mac address 00:0F:EA:91:04:07

iptables -A INPUT -p tcp –destination-port 22 -m mac –mac-source
00:0F:EA:91:04:07 -j ACCEPT

Read man page of iptables for more information.

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FreeBSD Time/Clock Synchronization with NTP server

funtoosh — Sun, 04 Mar 2007 07:33:01 +0000

FreeBSD use the Network Time Protocol (NTP) for synchronising the clocks of computer systems over packet-switched, variable-latency data networks. NTP uses UDP port 123. If you have one computer or single server then you can easily synchronization time with other NTP servers. All you need is ntp client called ntpdate. It is use to set the date and time via NTP servers.

Step # 1: Install NTP

# pkg_add -rv  ntp

# cd /usr/ports/net/ntp
# make; make install

Step # 2: Pick appropriate NTP Servers
Visit public ntp timeserver list to pick up your NTP server.

Step # 2: Open UDP port 123 at firewall

If you are running FreeBSD ipfilter firewall then you need to open the UDP port 123. Just add following rule to your firewall script:

pass out quick on lnc0 proto udp from YOUR-SERVER to any port = 123
keep state

pass out quick on lnc0 proto udp from YOUR-SERVER to
TIME-SERVER-IP port = 123 keep state

For example, my FreeBSD workstation IP is 192.168.1.16 and 61.246.176.131 is IP of NTP server then my rule is in ipf.conf file as follows:

pass out quick on lnc0 proto udp from 192.168.1.16
to 61.246.176.131 port = 123 keep state

Step # 4: Test clock Synchronization
Just run ntpdate command as follows to see you can set date and clock via NTP:
a) Set wrong date (Mon Dec 13 4:27 pm)

# date 0412131627

b) Now set correct date with ntp:

# ntpdate -v -b in.pool.ntp.org

13 Dec 16:27:50 ntpdate[997]: ntpdate 4.2.0-a Thu Nov 3 07:34:22 UTC 2005 (1)
25 Jan 12:35:47 ntpdate[997]: step time server 61.246.176.131 offset 35237275.965726 sec

c) You can verify that correct data is setup:

# date

Wed Jan 25 12:36:21 IST 2006

Step # 5 : Enable date and time/ clock Synchronization at boot time
You need to set ntpdate via /etc/rc.local file.

# vi /etc/rc.local

Append following line to it:
ntpdate_enable=”YES”
ntpdate_hosts=”asia.pool.ntp.org”

Save the file. Make sure you have correct ntpdate_hosts server entry.

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Increase security by Locking Admin screen/console

funtoosh — Sun, 04 Mar 2007 07:31:27 +0000

This is especially useful for Linux/BSD/Unixish system which have multiple users with access to the console. One user may lock his or her session while still allowing other users to use the system on other virtual consoles. If desired, the entire console may be locked and virtual console switching disabled. This is really a good idea to lock your workstation which is use to control other servers in your network environment. Both FreeBSD and Linux support locking the screen option. Generally, KDE and Gnome include a locking feature. The idea is very simple secure your terminal from unwanted people.

Shell variables to auto-logout
Almost all-modern shell support some sort of auto logout option. Under BASH you need to use TMOUT variable. You can setup TMOUT in seconds, bash terminates after waiting for that number of seconds if input does not arrive. For example if you setup TMOUT 60 seconds:

$ export TMOUT=60

So, if no input (command typed) arrived it will terminate shell with following message:
timed out waiting for input: auto-logout

You can add TMOUT to your shell configuration file ~/.bash_profile file.

However, I liked tcsh shell (the default shell under FreeBSD) autologout variable. Genral syntax is as follows:
$ set autologout = (VAL1 VAL2)

Where,
VAL1 : The number of minutes of inactivity before automatic logout
VAL2 : The number of minutes of inactivity before automatic locking will take place this is optional.
For example, you can set autologout as follows.

$ set autologout = (5 10)

You can add autologout to your shell configuration file ~/.cshrc OR ~/.tcshrc.

Using vlock under Linux to lock screen
vlock is a program to lock one or more sessions on the Linux consol. Install it using apt-get or yum:

# apt-get install vlock

OR if you are a Fedora user

# yum install vlock

Now to lock your console or screen just type vlock command at shell prompt:

$ vlock

This TTY is now locked.
Please enter the password to unlock.
admins's Password:

Using lock command under FreeBSD/OpenBSD
The lock command requests a password from the user, reads it again for verification and then will normally not relinquish the terminal until the password is repeated.

$ lock

Key:
Again:
lock: /dev/ttyp0 on fbsd6.unix.org.in. timeout in 15 minutes.
time now is Tue Jan 31 20:46:14 IST 2006
Key:

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NTFS-3G has just gone 1.0

funtoosh — Thu, 22 Feb 2007 08:12:35 +0000

It looks like NTFS-3G has just hit 1.0. The release history page today said: “Stable Version 1.0 (February 21, 2007) change: document and release version update to stable status” Readers are reminded at this point that 1.0 (which in the Windows world often means “little better than beta”) has a very near magical meaning in Linux-land.

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