usefulgeek » jonmoore

Moving /home to new partition

jonmoore — Mon, 19 Jul 2010 16:48:21 +0000

If /home is just a folder under / and you have a reason to put this on it’s own partition the process isn’t that difficult. Here is the steps I followed to do this.

First, create the new partition on the drive. I was using LVM, so I created a new logical volume, do whatever makes sense for your system here.

Make a place for the new home partition to be mounted while we transfer files.

mkdir /mnt/newhome
mount -t   /mnt/newhome

Move files from current /home to this new location.

cd /home
cp -ax * /mnt/newhome

Once all the files have copied, remove the old home directory, and mount the new partition in its place.

rm -r /home
mount  -t   /home

Edit /etc/fstab for the new partition, and you’re done.

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Lock and Unlock Linux accounts

jonmoore — Thu, 22 Apr 2010 13:37:06 +0000

Using passwd it is possible to quickly lock and unlock Linux accounts. To lock an account. passwd -l username To unlock an account. passwd -u username Related posts:Quick install of Tomcat5 on CentOS At the office, we’re in the process of doing some... Related posts brought to you by Yet Another Related Posts Plugin. Related posts:

Quick install of Tomcat5 on CentOS At the office, we’re in the process of doing some...

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Using telnet to test POP server

jonmoore — Wed, 21 Apr 2010 14:52:28 +0000

Using telnet (or putty) it’s possible to some simple tests against a POP server. By no means exhaustive, it can give you insights in where to start troubleshooting.

First, using telnet and open a connection the remote POP server

telnet mailserver 110

Where mailserver is the mail server you want to connect to. Note that port 110 is the default port for POP, but could be different depending on your servers settings.

Once connected, use USER and PASS to login.

[root@ms1 ~] # telnet localhost 110
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
+OK POP3 localhost v2001.78rh server ready
USER username
+OK User name accepted, password please
PASS password
+OK Mailbox open, 1 messages
QUIT
+OK Sayonara
Connection closed by foreign host.

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Linux IPv6 Neighbor Discovery

jonmoore — Tue, 20 Apr 2010 21:37:54 +0000

Using ping6 and ip neigh it’s possible to discover other IPv6 hosts on your local network using the link-local addresses.
First, use ping6 to ping all hosts on the local network using the IPv6 link-local address

ping6 -c 2 -I eth0 ff02::1

Then, use ip neigh to show a list of IPv6 enable hosts on the local network

ip -f inet6 neigh

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Why use ZFS with FreeNAS?

jonmoore — Tue, 09 Mar 2010 03:43:29 +0000

I recently started using FreeNAS again after exploring other options that existed, such as openfiler, and now that I’ve returned, ZFS seems to be the cool thing to do. After reading, watching videos and playing with ZFS I’m sold on all the features it offers. However, I must ask, is there a compelling reason to use ZFS over UFS for a single disk? I’d really like to see some comments on this.

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Rewrite incoming CallerID

jonmoore — Fri, 26 Feb 2010 21:38:27 +0000

We’re using asterisk, and as part of the dial plan, a 9 is required before the number to make calls out to the PSTN. Since our phones have a incoming call log, it would be very convient to have asterisk rewrite the CallerID value on calls from the PSTN to include this leading digit. I found this was rather easy to accomplish. Adding something similar to the following to whatever extension handles your incoming calls, all CallerID numbers will have a 9 added to the front.
exten => s,1,Set(CALLERID(num)=9${CALLERID(num)})
And proceed with your normal call routing logic. Change the preceding digit to whatever matches your system. If you have several extensions this is going to be used with, you could benefit from using a global variable for the leading digit.

Asterisk GotoIf Application The description from asterisk for this is GotoIf(condition?[labeliftrue]:[labeliffalse]), however for...

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Asterisk GotoIf Application

jonmoore — Fri, 22 Jan 2010 15:12:20 +0000

The description from asterisk for this is GotoIf(condition?[labeliftrue]:[labeliffalse]), however for me (being somewhat new to asterisk, and not fully understanding all the little bits, this was a bit confusing. A better way of describing this, at least for those of use new to asterisk, might be GotoIf(condition?[context,priority,labeliftrue]:[context,priority,labeliffalse]).
I have not used labels in the dial plan before, and when starting out with this application I read label to be a context. This lead me to write my dial plan similar to this..

[default]
exten => 100,1,GoToIf(condition?true,false)
[true]
exten => s,1,...
[false]
exten => s,1,...

In retrospect, it’s obvious what the documentation is saying, but as I said, not being familiar with labels, I was a bit lost.

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Remote packet capture

jonmoore — Sun, 17 Jan 2010 19:52:43 +0000

Had a need to capture some traffic on the remote machine and analyze it in Real Time ™. Found to solutions to this. The first, involved just sending the output of tcpdump across the ssh session.
ssh host.example.org tcpump - eth0 -w - > capture.pcap

The other method, picked up from the wireshark wiki allows for the captured traffic to be viewed as it’s being captured in wireshark. This is done using a combination of ssh and a fifo pipe. The exact command can very slightly, and I suggest reading the relevant man pages, but something similar to the following (taken from their wiki) should do the trick.
mkfifo /tmp/pipe ssh user@remote-host "tshark -w - not port 22" > /tmp/pipe wireshark -k -i /tmp/pipe

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Unable to use pvmove

jonmoore — Tue, 24 Nov 2009 22:50:25 +0000

I needed to remove a physical volume from a LVM volume group, and found this is done using the pvmove command. However, trying to run this, resulted in an immediate, and suprising error

# pvmove /dev/sdb1 /dev/sdc1
Required device-mapper target(s) not detected in your kernel

After some quick google’ing I found on this list a cause, and a fix. Appreantly, pvmove uses something provided by the raid1 module to do it’s magic. So, loading loading the dm-mirror kernel module fixes the issue and pvmove works as expected. Thanks debian-user list

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Quick install of Tomcat5 on CentOS

jonmoore — Wed, 18 Nov 2009 19:19:27 +0000

At the office, we’re in the process of doing some work where we need a tomcat server. Without having to get into things to much, I found this simple method for getting tomcat5 up and running pretty quickly. I’m sure I’ve left out some important things, and I’m doubtful as to how production ready this is, but for our testing, it’s working out fine.

I’m using CentOS 5.3 for all of this, but I’m sure it will work with CentOS 5.4

yum install tomcat5 tomcat5-admin-webapps tomcat5-webapps

After this, you need to edit the tomcat-users.xml file to create a new user.Using the above, this file ends up in /etc/tomcat5/tomcat5-users.xml and all that needs to be added is a line similar to the following..

user username="admin" password="p@ssw0rd" roles="admin,manager"

I can’t get wordpress to work with me on this, so you’ll need to wrap the above in angle brackets, the same as all the other lines in that file.
You can set username and password to whatever you’d like. After this, restart tomcat (not sure if this is needed) with service tomcat5 restart and off you go.

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