Printing from a CUPS server to Windows 7

A colleague of mine has some family issues that require him to be home more often. However, work continues. So he started working at home with a laptop. Nothing special about that. What is special, is that we're running a piece of software ("RR") that has old-style telnet-like terminals, which is sending it's print jobs straight to the printer.

His laptop has a direct VPN connection to the company network, but his printer doesn't.

Network info

The old software ("RR") is running on a pretty new RHEL 5.6 installation. It uses CUPS to queue and deliver print jobs. In my situation, the RR printer has zero printers configured, there's another Linux server that has all printers configured and broadcasts those printers over the network. But you could leave that print server out.

Problem

RR cannot reach the printer directly. But it can reach the laptop, which is running Windows 7 Professional. I searched for an IPP server that I could install on Windows, so that the printserver could use that to relay messages to the local printer, but I couldn't find any.

Solution

Windows 7 still has the option to install an lpd server. It's not installed by default, but it's very simple to install.

Windows setup:

  • In the Windows 7 Control Panel
  • Go to the "Programs and Features"
  • Click "Turn Windows Features on or off"
  • Turn on the LPD protocol.
  • Now go to the "printers" and share all printers you want to share.
  • Don't use long names and names with spaces, like "HP Laserjet 4200 Series", which are hard to setup on the client. Use something short like hplj4200.

Client setup:
Now you can setup the client to print to lpd://[ip-or-hostname-of-client]/[printername], for example lpd://10.10.10.17/hplj4200

If you can't get it to work, please check printer permissions and the firewall of the Windows 7 machine, which must have port 515 open.

© GeekLabInfo Printing from a CUPS server to Windows 7 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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WordPress: custom links on plugin page

Since WordPress 2.8, you can easily add your own links to the plugin page. This can be useful to jump right to the settings of the plugin. Example code:

function set_plugin_meta($plugin_meta, $plugin_file, $plugin_data, $status){
if (plugin_basename(__FILE__)!=$plugin_file) return $plugin_meta;
return array_merge( $plugin_meta, array( sprintf( '<a href="options-general.php?page=%s">%s</a>', $plugin, __('Settings') ) ));
}
add_filter( 'plugin_row_meta', 'set_plugin_meta', 10, 2 );

Two other interesting plugin hooks are:

do_action( 'after_plugin_row', $plugin_file, $plugin_data, $status );
do_action( "after_plugin_row_$plugin_file", $plugin_file, $plugin_data, $status );

These are both run after the row was printed.

© GeekLabInfo WordPress: custom links on plugin page 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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An Asterisk 1.8 fax server

To start, I setup a clean, minimal Fedora 15 installation.

Install requirements

After installation, we install a few more tools that we need:
yum install asterisk asterisk-fax #base
yum install perl-Email-MIME libtiff-tools #for mailer script
yum install telnet mc vim ntp rsync #for convenience and backup

Synchronize your time:
sntp -s pool.ntp.org

Configuration

On a clean asterisk installation, we only edit a few files.

sip.conf
Edit /etc/asterisk/sip.conf and make the following changes:

  • Look for ;faxdetect=yes and uncomment it by removing the ;
  • Somewhere under [global] put your register string. For example:
    register => myUsername:myPassword@12.34.56.78/31331234567
    In this example 12.34.56.78 is the ip of my SIP provider and 31331234567 my internationalized fax number.
  • At the bottom, add the following lines:
    [trunk-geeklab-9]
    username=myUsername
    type=peer
    secret=myPassword
    qualify=yes
    host=12.34.56.78
    canreinvite=yes
    context=geeklab-fax
    insecure=invite

extensions.conf
To /etc/asterisk/extensions.conf add the following lines:
[geeklab-fax]
exten => 331234567,1,Goto(inboundfax,s,1)
;This is the DID number my provider rings. I would
;prefer 3133123... or 033123... but that's just the
;way it is. Your provider may use another format.

[inboundfax]
;I could have merged this with [geeklab-fax] but i decided not to.
exten => s,1,NoOp(**** FAX RECEIVED from ${CALLERID(num)} ${STRFTIME(${EPOCH},,%c)} ****)
exten => s,n,Set(FAXOPT(ecm)=yes)
exten => s,n,Set(FILENAME=fax-${STRFTIME(${EPOCH},,%Y%m%d-%H%M%S)}-${CALLERID(num)})
exten => s,n,Set(FAXFILE=${FILENAME}.tif)
exten => s,n,Set(FAXOPT(ecm)=yes)
exten => s,n,Set(FAXOPT(headerinfo)=Received by MYCOMPANY ${STRFTIME(${EPOCH},,%Y-%m-%d %H:%M)})
exten => s,n,Set(FAXOPT(localstationid)=0331234567)
exten => s,n,Set(FAXOPT(maxrate)=14400)
exten => s,n,Set(FAXOPT(minrate)=2400)
exten => s,n,NoOp(FAXOPT(ecm) : ${FAXOPT(ecm)})
exten => s,n,NoOp(FAXOPT(headerinfo) : ${FAXOPT(headerinfo)})
exten => s,n,NoOp(FAXOPT(localstationid) : ${FAXOPT(localstationid)})
exten => s,n,NoOp(FAXOPT(maxrate) : ${FAXOPT(maxrate)})
exten => s,n,NoOp(FAXOPT(minrate) : ${FAXOPT(minrate)})
exten => s,n,NoOp(**** RECEIVING FAX : ${FAXFILE} ****)
exten => s,n,ReceiveFAX(/var/spool/asterisk/fax/${FAXFILE})
exten => s,n,Hangup()
exten => h,1,NoOp(FAXOPT(ecm) : ${FAXOPT(ecm)})
exten => h,n,system(/usr/local/bin/fax-process.pl --to yourname@geeklab.info --from fax@geeklab.info --subject "Fax from ${URIENCODE(${CALLERID(number)})} ${URIENCODE(${CALLERID(name)})}" --attachment ${FILENAME}.pdf --type application/pdf --file ${FAXFILE});

Inbound fax notification

When you get a fax, you'll probably want it in you mailbox. Download fax-process.txt and move it to /usr/local/bin/fax-process.pl. Make it executable using chmod 755 /usr/local/bin/fax-process.pl. If you haven't disabled SELinux, change the files security context by running: chcon system_u:system_r:asterisk_t:s0 fax-process.pl

Firewall

You won't get any calls if the firewall drops them. You may want a complex firewall. But since I'm using this virtual machine as a dedicated fax, I allow all from my SIP host and nothing from other hosts. Edit /etc/sysconfig/iptables to reflect your preferences. Mine are:
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [59:6844]
-A INPUT -s 12.34.56.78 -p tcp -m tcp ! --dport 22 -j ACCEPT
-A INPUT -s 12.34.56.78 -p udp -m udp -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp -s my.ho.me.ip --dport 22 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

You're done

Start asterisk by running service asterisk start and you're good to go.

© GeekLabInfo An Asterisk 1.8 fax 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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Dracut: add drivers to your initrd

My HP 8150w laptop has this neat lis3lv02d accelerometer to be able to detect when it's falling and to park the harddisk to prevent damage. I use this instrument to detect whether I'm on the road or at the office. This way, I can set preferences at boot-time, even before the network settings are loaded.

I have added a few scripts to my initrd, which are not very interesting. But what is, is the driver required to do this.

I created a file named /etc/dracut.conf.d/tilt.conf which contains:
add_drivers="$add_drivers hp_accel lis3lv02d input_polldev"

After creating a new initrd by running dracut, my scripts can see the x/y/z tilt of the machine by reading from /sys/devices/platform/lis3lv02d/position

© GeekLabInfo Dracut: add drivers to your initrd 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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Find the Dell Service Tag Remotely

Windows with VNC/RDP

If you can login to the computer over VNC or RDP, you can use wmic to find the service tag:
start > run > cmd
On the command line, enter:
wmic bios get serialnumber

Windows without VNC/RDP

If you cannot login to the computer over VNC or RDP, you can still use wmic to find the service tag:
start > run > cmd
On the command line, enter:
wmic /node:computer-name-here bios get serialnumber
You may need to use /user:yourusername and /password:yourpassword to get access to the remote computer. Running wmic /? gives a pretty good manual on what wmic can do.

Other uses of wmic

wmic is a very useful tool for a lot of stuff. For instance wmic csproduct can tell you exactly what model the computer is and wmic nic list shows useful information about your network.

Linux

Under Linux, you can run dmidecode -s system-serial-number to get the serial number. This can be done locally or over ssh.

© GeekLabInfo Find the Dell Service Tag Remotely 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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Lovelock: Mozilla as default browser from Thunderbird

Last week, I upgraded to Fedora 15 (codename: Lovelock). One of the new annoying "features" is that Google Chrome somehow got to be the default browser when I click a link from Firefox.

I Google'd around, and couldn't find how to fix it. So I decided to strace it. Apparently, Thunderbird launches gvfs-open to open a browser. Again I straced the command "gvfs-open https://www.geeklab.info", and found that it opens /usr/local/share/applications/defaults.list, which referred to google-chrome.desktop instead of mozilla-firefox.desktop. My file now contains:

[Default Applications]
text/html=mozilla-firefox.desktop
text/xml=mozilla-firefox.desktop
application/xhtml_xml=mozilla-firefox.desktop
x-scheme-handler/http=mozilla-firefox.desktop
x-scheme-handler/https=mozilla-firefox.desktop
x-scheme-handler/ftp=mozilla-firefox.desktop

And it's fixed! :-)

Update: Since some crap keeps changing this file, i just made the file immutable. The command chattr +i /usr/local/share/applications/defaults.list prevents programs that would normally have permissions to edit the file to be blocked.

© GeekLabInfo Lovelock: Mozilla as default browser from Thunderbird 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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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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