GL.IB.LY » tidbits

Installing SNMPD (with remote access) on Debian 5/Lenny

tariq — Wed, 10 Mar 2010 07:18:10 +0000

Today we’re installing snmpd so that we can query our debian server from another remote server that will use snmp in alert scripts and pretty graphing software.

Snmpd installation is a little obtuse so here is how to do the installation on Debian Lenny.

Install snmpd with: sudo apt-get install snmpd

You should be using RCS/git/etc when editing system files at work. So use the appropriate techniques for checking in and out all conﬁg ﬁles. If you’re a home user don’t worry about this step; or, maybe you should. Muhahahaha! Eh, *cough*.

Open /etc/snmp/snmpd.conf and change to the following:# sec.name source community #com2sec paranoid default public #com2sec local localhost public com2sec local localhost mysecretcommunity com2sec readonly 192.168.XXX.XXX mysecretcommunity #com2sec readwrite default private

Here mysecretcommunity is the uber secret name of your community. Change this to something other than public or mycommunity — let common sense prevail. 192.168.XXX.XXX is the IP address of your remote server that will query snmpd.

Change /etc/default/snmpd so that it contains the following line:
```
SNMPDOPTS=’-Lsd -Lf /dev/null -u snmp -I -smux -p /var/run/snmpd.pid’
```
Notice the lack of 127.0.0.1?

Save the ﬁle!

Restart snmpd with sudo /etc/init.d/snmpd restart.

Test snmpd locally:

snmpwalk -Os -c mysecretcommunity -v 1 localhost system

Test snmpd remotely from 192.168.XXX.XXX:
```
snmpwalk -Os -c mysecretcommunity -v 1 192.168.YYY.YYY system
```
Here 192.168.YYY.YYY is the IP address of the debian server hosting snmpd.

Verify test outputs look like:
... sysObjectID.0 = OID: netSnmpAgentOIDs.10 sysUpTimeInstance = Timeticks: (1201) 0:00:12.01 sysContact.0 = STRING: root sysName.0 = STRING: irsplsemos01 sysLocation.0 = STRING: Unknown sysORLastChange.0 = Timeticks: (0) 0:00:00.00 sysORID.1 = OID: snmpFrameworkMIBCompliance sysORID.2 = OID: snmpMPDCompliance sysORID.3 = OID: usmMIBCompliance sysORID.4 = OID: snmpMIB sysORID.5 = OID: tcpMIB sysORID.6 = OID: ip sysORID.7 = OID: udpMIB sysORID.8 = OID: vacmBasicGroup ...

Thats all folks!

The post Installing SNMPD (with remote access) on Debian 5/Lenny appeared first on GL.IB.LY.

Fixing binary merge conflicts in git

tariq — Thu, 03 Sep 2009 06:59:37 +0000

Git is an awesome tool for managing your code. However, it does take a while to get used to doing things in git. One question I get asked a bit too often is “how do I resolve binary merge conflicts”? Thankfully this is is pretty easy. I usually run the git mergetool command to allow me to resolve merge conflicts using a graphical interface and then manipulate the resultant files on the command line.

You can specify which editor to use in your ~/.gitconfig file. Favourites are kdiff3, vimdiff, xxdiff, and opendiff. If your on Mac OSX then you may be used to FileMerge, in which case you should be using opendiff in your .gitconfig; see below.

... [merge] tool = opendiff ...

So, when you are using mergetool option you will something like:

Normal merge conflict for 'lib/yui/assets/skins/sam/editor-sprite.gif':

{local}: created

{remote}: created

Hit return to start merge resolution tool (opendiff):

I just hit return so the editor opens, it will probably warn you the file is binary. In a separate terminal window navigate to the directory where the file is in and do an ls; you’ll see something like what is below:

editor-sprite.gif

editor-sprite.gif.BACKUP.41930.gif

editor-sprite.gif.LOCAL.41930.gif

editor-sprite.gif.REMOTE.41930.gif

In this case editor-sprite.gif.REMOTE.41930.gif is the new file and editor-sprite.gif is the original file. To resolve the conflict just copy the REMOTE file over the original file. In my case it would be cp editor-sprite.gif.REMOTE.41930.gif editor-sprite.gif. However, I use the following one liner to resolve these conflicts more generically.

ls *.REMOTE.* | sed “s/\(\(.*\).REMOTE.*\)/cp \1 \2/g” | sh

I have it in shell script in my path so I just run it when I need to resolve these types of conflicts. It just finds files with REMOTE in them and then issues a cp command to copy that file over the original.

Hope this helps!

Outside of git mergetool you can just add the binary files using git add file1 file2 ….

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Searching compressed Apache logs

tariq — Tue, 23 Jun 2009 06:27:23 +0000

From time to time things tend to go wrong and systems tend to go crazy. Sometimes these errors are more of nuisance than anything else, an intermittent annoyance you’d prefer not to investigate — trawling through logs is a pain in the backside. Now you need to take a peak at those compressed Apache error log files, ugh! Well before you look for suitable places to hang some rope try running some expressions across a certain number of files. Normally you’d only want to look at logs for the last 7 days, so lets give that a go.

The error messages I am interested in all contain the text Healthcheck so I will use trusty grepfind matching lines in the logs. I will use find to get me all the files modified in the last seven days. A program called xargs will then be used to call cat which will pipe to a compression program which finally pipes to grep. Put this all together and you get something like this:

find /var/log/apache2 -type f -name "error_*.bz2" -mtime -7 | sort | xargs cat | bunzip2 | grep"Healthcheck"

If your files are tar.gz then you’ll need to replace bunzip2 with gzip -dc. So that would look like:

find /var/log/apache2 -type f -name "error_*.tar.gz" -mtime -7 | sort | xargs cat | gzip -dc |grep "Healthcheck"

Have fun!

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Rubber hose attacks!

tariq — Sat, 07 Feb 2009 06:07:10 +0000

Awesome! Hot linked from xkcd. Also, checkout wikipedia for more details on what the Russians do and how public key cryptography could get you killed or landed in jail (if you live in the uk).

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