Author: David (admin)

IT

Native IPv6: First steps

Today I made my first native IPv6 connection. I've been running Teredo/Miredo on my laptop for quite a while now, and I thought it was time to get a real IPv6 connection. I could use IPv6 autoconfiguration, but on a server you need a fixed IP.

Needed software

Install required packages that are not included in the Fedora default install:
yum install iproute2 ndisc6

Configuring manually

Configuring the network is not that much different from configuring an IPv4 address.

IPv4IPv6
ip addr add 1.2.3.4/24 dev eth0ip addr add 2001:1BE8:DEAD:BEEF::1a1a/64 dev eth0
ip route add default via 1.2.3.254ip route add default via 2001:1BE8:DEAD:BEEF::1

Now test it by pinging/tracerouting some known IPv6 services:

[root@localhost ~]# ping6 ipv6.google.com
PING ipv6.google.com(2a00:1450:8003::69) 56 data bytes
64 bytes from 2a00:1450:8003::69: icmp_seq=1 ttl=58 time=7.19 ms
64 bytes from 2a00:1450:8003::69: icmp_seq=2 ttl=58 time=7.52 ms
64 bytes from 2a00:1450:8003::69: icmp_seq=3 ttl=58 time=6.98 ms
64 bytes from 2a00:1450:8003::69: icmp_seq=4 ttl=58 time=7.44 ms
^C
--- ipv6.google.com ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3003ms
rtt min/avg/max/mdev = 6.989/7.287/7.525/0.227 ms
[root@localhost ~]# tracert6 ipv6.google.com
traceroute to ipv6.google.com (2a00:1450:8003::69) from 2001:1be8:dead:beef::1a1a, 30 hops max, 60 bytes packets
1 2001:1be8:dead:beef::1 (2001:1be8:3f03:541::1) 1.024 ms 0.970 ms 1.036 ms
2 2001:1be8::310:1 (2001:1be8::310:1) 2.618 ms 2001:1be8::300:1 (2001:1be8::300:1) 2.583 ms 2001:1be8::310:1 (2001:1be8::310:1) 2.527 ms
3 pr61.ams04.net.google.com (2001:7f8:1::a501:5169:1) 2.865 ms 2.536 ms 2.184 ms
4 2001:4860::1:0:4b3 (2001:4860::1:0:4b3) 2.801 ms 3.156 ms 24.731 ms
5 2001:4860::2:0:66e (2001:4860::2:0:66e) 7.021 ms 6.830 ms 96.541 ms
6 2001:4860:0:1::31 (2001:4860:0:1::31) 7.092 ms 7.367 ms 12.089 ms
7 2a00:1450:8003::69 (2a00:1450:8003::69) 6.996 ms 7.550 ms 7.341 ms

Configure at boot time

Step 1. Enable IPv6 networking

vim /etc/sysconfig/network
then add (or replace):
NETWORKING_IPV6=yes

Step 2. Configure IPv6 addresses

vim /etc/sysconfig/network-scripts/ifcfg-eth0
then add the following lines:
IPV6INIT=yes
IPV6ADDR=2001:1BE8:DEAD:BEEF::1a1a/64
IPV6_DEFAULTGW=2001:1BE8:DEAD:BEEF::1

Step 3. Test

Run service network restart or reboot to test.
Warning: if you do this remotely, you may lose the connection. I first locked myself out of my test machine, but I always got a KVM switch attached or VMWare console.

Security

Please remember that using IPv6 also means that there's a new entrance to your network. Use ip6tables to set up a firewall.

Ubuntu/Debian

I'm running RedHat-based software on all of my machines. Above information may be useful for Ubuntu/Debian users, but it's not tested and I'm not supporting it.

Servers: RedHat Enterprise Linux/CentOS is more suitable for servers, as there's a lot of professional level support available. I think that's important, because if I say, get a car accident, I want the servers to be managable by another professional.

Desktops/Laptops: RPM packages are pretty exchangable between RedHat-based platforms. That's a good reason to run Fedora on the desktop.
© GeekLabInfo Native IPv6: First steps is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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Networking

Firewall your Exchange 2007 server

Software that is not reachable, can't be hacked. Easy as that. So if you have an cloud-based anti-spam/anti-virus filter, you can block your smtp server for badguys.

In my situation, I'm using a Windows 2008 SBS server with Exchange 2007.

  1. Start wf.msc
  2. Go to inbound rules
  3. Find MSExchangeTransportWorker and double-click it to open the properties
  4. On the tab "scope", select "These IP addresses" and add the following IPs: 'Local subnet', 127.0.0.0/8, 192.168.0.0/16, fe80::/16
  5. Also add the IPs of your anti-spam servers as well
  6. Then click OK
  7. Don't forget to check that the changes actually work by both checking an IP that can connect and one that doesn't
© GeekLabInfo Firewall your Exchange 2007 server is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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IT

Run a batch file invisibly

Save this one line of text as c:\windows\quiet.vbs
CreateObject("Wscript.Shell").Run """" & WScript.Arguments(0) & """", 0, False
To run a batch file invisibly, start it using the following command:
wscript.exe "C:\windows\quiet.vbs" "C:\path\file.bat"

© GeekLabInfo Run a batch file invisibly is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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IT

Error 1913: Setup cannot update file C:\windows\win.ini

Installing Microsoft Office 2010 using the preinstalled "out of the box" function, I got this error:
Error 1913: Setup cannot update file C:\windows\win.ini

Permissions were right. I could rename the file, so that means it was not in use by some other program... but apparently it was Trend Micro blocking the installation.

Using services.msc I disabled all Trend Micro stuff, finished the install and rebooted to get all services running as normal.

© GeekLabInfo Error 1913: Setup cannot update file C:\windows\win.ini is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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IT

Squid active directory authentication on Centos 5.6

Step 1. Install ntp and synchronize clocks

We'll be using winbind, kerberos and ntlm to authenticate the user. This requires the clocks of the AD server and the proxy server to be synchronized.
rpm -qa ntp || yum -y install ntp
sed -i "s/^server /#server /g" /etc/ntp.conf
echo "server YOURSERVERNAME" >> /etc/ntp.conf
ntpdate YOURSERVERNAME #synchronize right now
service ntpd start #and keep in sync
chkconfig ntpd on #after reboot as well

Step 2. Install required software

yum install krb5-workstation samba-common authconfig squid
chkconfig squid on

Step 3. Connect to active directory

Please note that MYCOMPANY.local and mycompany.local may be different domains due to the upper/lowercase.
ADSERVER=sbs.MYCOMPANY.local
DOMAIN=MYCOMPANY.local
WORKGROUP=MYCOMPANY
authconfig --enableshadow --enablemd5 --passalgo=md5 --krb5kdc=$ADSERVER \
--krb5realm=$DOMAIN --smbservers=$ADSERVER --smbworkgroup=$WORKGROUP \
--enablewinbind --enablewinbindauth --smbsecurity=ads --smbrealm=$DOMAIN \
--smbidmapuid="16777216-33554431" --smbidmapgid="16777216-33554431" --winbindseparator="+" \
--winbindtemplateshell="/bin/false" --enablewinbindusedefaultdomain --disablewinbindoffline \
--winbindjoin=Administrator --disablewins --disablecache --enablelocauthorize --updateall

I found some information saying that /var/cache/samba/winbindd_privileged should be chowned 750 to root:squid or that you should add user squid to group wbpriv. Also, squid.conf should not have cache_effective_group defined. However, this part was not relevant on my Centos 5.6. The reason could be that I installed 5.4, then upgraded, i'm not sure. Just leaving it as a note.

Now check your winbind connection using the following commands:
wbinfo -u
wbinfo -g

Step 4. Configure squid

auth_param ntlm program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp
auth_param ntlm children 5
auth_param ntlm keep_alive on
acl our_networks src 192.168.0.0/16
acl ntlm proxy_auth REQUIRED
http_access allow our_networks ntlm
authenticate_ip_ttl 900 seconds

This will allow all valid, logged in users to surf the web. You could also limit which users can surf by adding
--require-membership-of=ADGROUPNAME to the ntlm_auth command

Start Squid using /sbin/service squid restart and you're good to go.

You may want to check what else I'm writing on Squid. I'm planning to document a lot more in the next few weeks.

© GeekLabInfo Squid active directory authentication on Centos 5.6 is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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IT

Arrrrgh! Kill it! Kill wp_attempt_focus with fire!

Somewhere around version 2.8.4 or something, WordPress introduced a "feature" to focus the username form and wipe the username. I dont want to type my username every time again and again and again. So what can we do to kill wp_attempt_focus? There is no hook available to disable that part of the code, but we can use some dirty tricks:

I created the following 'plugin' to get rid of it:
function kill_wp_attempt_focus($in){
return preg_replace('/function wp_attempt_focus/','function wp_attempt_focus(){} function wp_attempt_focus_killed',$in);
}
if($_SERVER["PHP_SELF"]=='/wp-login.php'){
ob_start('kill_wp_attempt_focus');
}

It grabs the output of /wp-login.php, renames the original wp_attempt_focus() to wp_attempt_focus_killed() and creates a new empty function to prevent errors.

© GeekLabInfo Arrrrgh! Kill it! Kill wp_attempt_focus with fire! is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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Desktop software

USB Video DVD Maker for Linux

Today I borrowed a USB video device, just to see if I can get it working on Linux. And I did! The device's package shows that is supports PAL (720x576@25fps) and NTSC (720x480 @ 30fps), but not much more.

According to lsusb, the device is built by eMPIA Technology, Inc and it has id eb1a:2861. Because I have another webcam attached, the device is connected to /dev/video1 is a character device with major 81 and minor 1. In the /sys filesystem, there's information on the device. I can find the right node using the next command:

cd /sys/dev/char/81:1

This is a symlink to (in my case) /sys/devices/pci0000:00/0000:00:1d.7/usb2/2-5/2-5:1.0/video4linux/video1. In this directory, I find some more useful information. The file name tells me the device is actually a em28xx-based device.

The device has 2 inputs: a serie of RCA connectors with a composite signal and a SVideo connector. This is represented by showing two "sub-devices". The composite signal is /dev/video1, while the SVideo connector is /dev/vbi0.

To display the screen of my Sony* HDR-SR11 camera, I use the command:

mplayer -cache 128 -tv driver=v4l2:device=/dev/video1:input=1:width=720:height=576:outfmt=i420 tv://

* Yes, a Sony. And I'm really sorry. I bought it several years ago. I'm boycotting Sony nowadays.

© GeekLabInfo USB Video DVD Maker for Linux is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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