Linux

For easier use with Cacti, it is easier to group statistics per type instead of per CPU. So you would have a parent OID for CPU time spent by user with many values (one per CPU). Put the following in /etc/snmp/percpudetail: #!/bin/bash case "$1" in "user") grep ^cpu /proc/stat | awk '{print 2}' ;; "nice") grep ^cpu /proc/stat | awk '{print 3}' ;; "system") grep ^cpu /proc/stat | awk '{print 4}' ;; "idle") grep ^cpu /proc/stat | awk '{print 5}' ;; "iowait") grep ^cpu /proc/stat | awk '{print 6}' ;; "irq") grep ^cpu /proc/stat | awk '{print 7}' ;; "softirq") grep ^cpu /proc/stat | awk '{print 8}' ;; esac Make it executable: ...

I needed to export detailed CPU statistics from Linux servers using SNMP. While UCD-SNMP-MIB export some detailed stats, it only does it for the whole system. I may have missed something easier though :-) So here is a BASH script, put it in /etc/snmp/percpustats: #!/bin/bash /bin/grep "^$1 " /proc/stat | sed -e 's/^cpu[0-9]* *//' | tr ' ' '\n' Make it executable: chmod +x /etc/snmp/percpustats This simple script takes a single argument, which is the cpu id you want to look at. By “cpu id”, I mean the first word of cpu* lines in /proc/stat . So cpu, cpu0, cpu1, etc. Here is a sample content of my /proc/stat file: ...

So you have your Unified Networking Lab (UNL) server running and you want to use arbitrary QEMU images with it. Here is how to create one. All UNL data is stored under /opt/unetlab , images are stored under /opt/unetlab/addons and QEMU images are a folder deeper under /opt/unetlab/addons/qemu . UNL expects to find images within directories named according to some scheme. The directory names must start with some keywords followed by anything you want. For Linux images, you need to name the directory linux-something, e.g. linux-ubuntu-14.04.5-amd64. You can find the list of supported image “types” in /opt/unetlab/html/templates. The names of the files are the prefixes needed for directory names. If you want to, you can edit those files to change the default parameters of the images (make a backup before you change anything). ...

You can find pretty cheap USB to Serial devices on Ebay. I bought one and received a device using a chip ch341. Unfortunately, the drive is bugged in Ubuntu 12.04 and 14.04. Fortunately, there is patch to fix it. Here is how to recompile the module to enjoy these devices. $ sudo apt-get source linux-source-3.13.0 linux-headers-$(uname -r) $ cd /tmp $ tar -xjf /usr/src/linux-source-3.13.0.tar.bz2 $ cd linux-source-3.13.0/ $ make oldconfig $ make prepare $ make scripts $ cp -v /usr/src/linux-headers-$(uname -r)/Module.symvers . $ cp /lib/modules/$(uname -r)/kernel/drivers/usb/serial/ch341.ko /lib/modules/$(uname -r)/kernel/drivers/usb/serial/ch341.ko.orig $ cd drivers/usb/serial $ cp ch341.c ch341.c.orig $ wget https://github.com/karlp/ch341-linux/raw/master/0001-usb-serial-ch341-Add-parity-support.patch $ cat 0001-usb-serial-ch341-Add-parity-support.patch | patch -p4 patching file ch341.c Hunk #1 succeeded at 349 (offset 3 lines). Hunk #2 succeeded at 370 (offset 3 lines). $ make -C /lib/modules/$(uname -r)/build M=$(pwd) modules $ sudo cp ch341.ko /lib/modules/$(uname -r)/kernel/drivers/usb/serial/ch341.ko $ sudo rmmod ch341 $ sudo modprobe ch341 Source for instructions: http://askubuntu.com/questions/515407/how-recipe-to-build-only-one-kernel-module ...

GNS3 Sourceforge account provides an OVA image ready to run gns3-server for those who want to use Cisco IOS on Unix images . However, at the time of this writing, the gns3-server version is outdated (1.3.3). The client must have the same version as the server to be able to connect to it. Here is how you can update the gns3-server inside the image. Note that you need Internet access for the update. ...

Recently I had to migrate services from a running Debian server to another one, with minimal downtime of services. I usually do this to P2V or V2V Linux systems, as this allows me to resize the new virtual machine to meet the services requirements (adjust disk size, inodes, partitionning, etc.). I have done this several times in the past on systems with Grub 1 but this is the first time with Grub 2, so I thought I’d share my process. ...

To monitor the status of a LSI RAID card, say for example a Dell PERC card, you will need to install NRPE, sudo, mpt-status and check_mpt.sh . Install sudo and NRPE via your package manager. You can grab mpt-status via apt if you use Debian/Ubuntu or here if you use CentOS. You can grab check_mpt.sh here. First, load the module mptctl if it’s not done already: modprobe mptctl To have the module loaded at boot, you can use your distribution specific behavior. In my case, I put it in /etc/rc.local . ...

I have been getting increasing number of errors in my Exim log related to GnuTLS Diffie-Hellman prime number. That prime number being too small causes Exim to abort the connection and initiate a new one to send the email over an unencrypted session. The exact error message is: TLS error on connection to foobar.example.com [x.x.x.x] (gnutls_handshake): The Diffie-Hellman prime sent by the server is not acceptable (not long enough). With a recent enough Exim installation, you can define the tls_dh_min_bits parameter to a value that you find acceptable. ...

To have rsyslogd automatically create directories and files with whatever you send at it, just put this in your rsyslog.conf file (or a .conf file in /etc/rsyslog.d): # provide UDP syslog reception $ModLoad imudp $UDPServerRun 514 $template DynFile,"/var/log/syslogs/%fromhost-ip%-%fromhost%/%$YEAR%-%$MONTH%-%syslogfacility-text%" # log everything from remote servers to one file per host+month+facility if $inputname == 'imudp' or $inputname == 'imtcp' then ?DynFile # stop logging from remote servers if $inputname == 'imudp' or $inputname == 'imtcp' then ~ All directories and files are created under /var/log/syslogs, one directory per ip-hostname pair, and one file per facility per month. ...

I had to migrate users from an Active Directory/Exchange combo to a SME server for temporary disaster recovery event. Here’s the script I wrote to create the export and recreate the users and their aliases in the SME server. The export was done before the disaster of course :) #!/bin/bash #ldapsearch -x -b "dc=customer,dc=com" -h 1.2.3.4 -D "domain\user" -W "(objectclass=user)" > activedirectory.ldiff File="activedirectory.ldiff" #reset files content echo > sme.users echo > sme.aliases cat "$File" | while read line do #concatenate new line to existing info UserInfo="$UserInfo $line" #treat all info if user is finished if $(echo -e "$line" | grep -q '^$') then echo User info finished #treat only users with mail address if $(echo "$UserInfo" | grep -q '^mail:') then #recover data UserName=$(echo "$UserInfo" | grep '^sAMAccountName:' | sed -e 's/sAMAccountName: //' | tr '\[A-Z\]' '\[a-z\]') UserFirstName=$(echo "$UserInfo" | grep '^givenName:' | sed -e 's/givenName: //') UserLastName=$(echo "$UserInfo" | grep '^sn:' | sed -e 's/sn: //') UserMail=$(echo "$UserInfo" | grep '^mail:' | awk '{print $2}' | tr '\[A-Z\]' '\[a-z\]') UserMailAliases=$(echo "$UserInfo" | grep '^proxyAddresses: smtp:' | sed -e 's/^proxyAddresses: smtp:\(.\*\)@.\*$/\1/' | sort -u | grep -vi "^${UserName}$" | tr '\n' '|' | tr '\[A-Z\]' '\[a-z\]') Tmp=$(dd if=/dev/urandom | tr -dc \_A-Z-a-z-0-9 | head -c 4) UserPassword=$(echo "${UserName}${Tmp}" | tr '\[A-Z\]' '\[a-z\]') #print user info echo "$UserName |$UserFirstName |$UserLastName |$UserPassword" >> sme.users #print aliases if any if \[ $(echo "$UserMailAliases" | wc -c) -gt 2 \] then echo "$UserName |$UserMailAliases" | sed -e 's/^\(.\*\)|$/\1/' >> sme.aliases fi #cleanup some shit unset UserName unset UserFirstName unset UserLastName unset UserMail unset UserMailAliases unset Tmp unset UserPassword fi unset UserInfo fi done You can then import all the users and their aliases with the following commands: ...