Month: April 2013

Broken pipe error on SSH session

Posted on by Andy

The "broken pipe" occurs when a SSH sessions times out. To resolve this you have 2 possibilities:

Server-Side (Linux):

  • open /etc/ssh/sshd_config
    # vim /etc/ssh/sshd_config
  • uncomment the lines:
    TCPKeepAlive Yes
    ClientAliveInterval 0 (change the 0 to 60, so every 60 seconds a keep alive packet is sent)
  • save the config
  • restart ssh server
    # service sshd restart

Client-Side (MacOSX/Linux):

  • open ~/.ssh/ssh_config (linux) or ~/.ssh/config (MacOSX)
  • add following lines:
    ServerAliveInterval 60 (send packet every 60 seconds)
  • save file

Recompile x86_64 kernel for CentOS 6.4

Posted on by Andy

Hi, due to some changes in the official CentOS 6 kernel like the integration of IPMI into the kernel (boot hanging bug) and the preemptive scheduling to "desktop" instead of "server" (which resulted in poorer performance) i decided to recompile the kernel.

Here is a small howto if you want to recompile your centos stock kernel with other options:

  1. create building tree as non-root user
    # su <user>
    # mkdir -p ~/rpmbuild/{BUILD,BUILDROOT,RPMS,SOURCES,SPECS,SRPMS}
    # echo '%_topdir %(echo $HOME)/rpmbuild' > ~/.rpmmacros
    # exit
  2. install needed packages:
    # yum groupinstall "Development Tools"
    # yum install hmaccalc zlib-devel binutils-devel elfutils-libelf-devel
    # yum install rpm-build redhat-rpm-config asciidoc hmaccalc
    # yum install binutils-devel elfutils-libelf-devel newt-devel zlib-devel ncurses-devel
    # yum install xmlto python-devel
  3. change user (NEVER RECOMPILE AS ROOT):
    # su <user>
  4. install source rpm:
    # rpm -ivh http://vault.centos.org/6.4/updates/Source/SPackages/kernel-2.6.32-358.2.1.el6.src.rpm
    ​    (6.4 -> centos version, kernel-2.6.32-358.2.1.el6.src.rpm -> kernel version)
  5. prepare source build tree
    # cd ~/rpmbuild/SPECS
    # rpmbuild -bp –target="x86_64" kernel.spec
  6. edit rpmbuild/SPECS/kernel.spec and replace line 18 with your custom build id:
    # %define buildid .custom.NOIPMI.SERVER
    (-> kernel-2.6.32.358.2.1.custom.NOIPMI.SERVER.x86_64.rpm)
  7. copy over old kernel config:
    # cd ~/rpmbuild/BUILD/kernel-2.6.32-358.2.1.el6/linux-2.6.32-358.2.1.el6.x86_64
    # cp /boot/config-2.6.32-358.2.1.el6.x86_64 .config
  8. now chane the kernel config to your desires:
    # make clean
    # make menuconfig
  9. then copy the config file to your SOURCE directory:
    # cp .config configs/kernel-2.6.32-x86_64.config
    # cp configs/* ~/rpmbuild/SOURCES
  10. launch the compile process:
    # cd ~/rpmbuild/SPECS
    # rpmbuild -bb –with baseonly –without debug –without debuginfo –target="x86_64" kernel.specs

​Now there should be some cryptic output to the screen. Lean back and have a coffee, the compilation process can take some time. Depending on your hardware this can take between 30 min and 3 hours (apparemtly up to 9 hours on a PentiumIII).

The compiled kernel can be found in the RPMS folder.

Ensim Quota Fixer

Posted on by Andy

Hello world,

We recently had some quota problems on one of our server with Ensim Control Panel. The control panel and command line quota tool reported other data than the users really used. Although the user had no files on the disk which were owned by him the quota reported a few megabytes used. I checked a few forums an read a few articles and wrote a bash script which fixes the quota problem.

Here what it does:

  • it turns off quota
  • does a backup of your old quota files (aquota.user and aquota.group)
  • scans new quota data
  • re-enables quota
  • and resets ensim users and admin quotas

Download the file, unzip it and run the script. Hope this helps someone as I struggled with this "bug" for some time.

Ensim Quota Fixer (820 downloads )