Welcome to Catalin(ux) M. BOIE's page!
Here you can find some work of mine on Linux kernel & other stuff.

E-mail: catab # embedromix dot ro
Phone: +40-745-048374
RSS feed for this site
My Fedora repository: rpm -Uhv http://kernel.embedromix.ro/dinorepo-0.0.12-1.noarch.rpm
My Oracle/RedHat/CentOS repository: rpm -Uhv http://kernel.embedromix.ro/dinorepo-el-0.0.13-1.noarch.rpm
Supported architectures: x86_64, i386, armv7hl, aarch64.
For commercial support and customizations, contact us at: Embedromix

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Name Description Links
Presentations Presentations made by me present.html
IFB A mini howto on how to shape on incoming packets and distribute packets on multiple interfaces, sharing bandwidth. ifb.html
RAID mini HOWTO A mini howto describing linear, 0, 1, 5 and 6, using mdadm. RAID.html
git mini HOWTO A mini howto describing how to use git. git.html
LVM mini HOWTO A mini howto describing how to use LVM. LVM.html
IPv6 mini howtos Some mini howtos to easy IPv6 implementation. ipv6.html
Random stuff Some usefull one-liners. random.html

Random stuff

  • Limit number of connections per second for ssh to maximum of 4 in 60 seconds:
    iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent --set
    iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent --update --seconds 60 --hitcount 4 -j DROP
  • Typing Unicode characters: CTRL+SHIFT+u, then the numeric code.
  • Making an SELinux domain permissive: /usr/sbin/semanage permissive -a httpd_t
  • Disabling HPA at boot (BIG WARNING: YOU CAN LOOSE DATA!): libata.ignore_hpa=1
  • Disabling HPA per disk (BIG WARNING: YOU CAN LOOSE DATA!): hdparm -N p<number_of_sectors> /dev/sd?
  • SELinux on low memory: /etc/selinux/semanage.conf: bzip-blocksize=4 and bzip-small=true
  • PostgreSQL: Find unused indexes: SELECT schemaname, relname, indexrelname, idx_scan, idx_tup_read, idx_tup_fetch FROM pg_stat_user_indexes;
  • PostgreSQL: Show activity: SELECT * FROM pg_stat_activity WHERE current_query != '<IDLE>';
  • Convert to ext4: tune2fs -O extents,uninit_bg,dir_index /dev/sdaaaa
  • Screencast: ffmpeg -f x11grab -g 250 -s 1024x768 -r 25 -y -sameq -i :0.0+0,0 x.avi.
  • Screencast (mkv): ffmpeg -f x11grab -g 250 -s 1024x768 -r 30 -y -sameq -i :0.0+0,0 -vcodec libx264 -vpre lossless_ultrafast -threads 0 x.mkv.
  • Keyboard fast rate: xset r rate 150 40
  • Dinamically grow a disk online under KVM/libvirt:
    Find devices: virsh domblklist NAME_OF_THE_MACHINE
    Resize: virsh blockresize NAME_OF_THE_MACHINE vda 12G
    'vda' may need to be replaced with something else.
    The size must be the final size! Do not shrink!
  • Reduce the memory usage of rsyslogd: $ActionQueueMaxFileSize 10000
  • Mozilla Firefox optimizations:
    Environment variables:
    export MOZ_ACCELERATED=1
    export MOZ_WEBRENDER=1

  • gfx.canvas.azure.accelerated -> true
    gfx.webrender.all -> true
    gfx.xrender.enabled -> true
    layers.acceleration.force-enabled -> true
    gfx.canvas.azure.backends = cairo
    gfx.content.azure.backends = cairo
    webgl.msaa-force -> true
  • Go to "about:support" to check status.
  • Video acceleration (RPMFusion must be present):
    dnf install libva libva-intel-hybrid-driver libva-intel-driver libva-utils mesa-vdpau-drivers vdpauinfo libva-vdpau-driver libvdpau-va-gl mesa-dri-drivers
    Optional: dnf install intel-media-driver
    Optional module parameters (i915): enable_guc=-1 enable_fbc=1
    Optional kernel parameters: pcie_aspm=force
  • Modern bridge and vlans (Neconf 2.2 presentation):
    ip link del cata-br-1 2>/dev/null
    ip link add cata-br-1 type bridge vlan_filtering 1
    bridge vlan del vid 1 dev cata-br-1 self
    ip li set dev cata-br-1 up
    ip link del cata-gre-1 2>/dev/null
    ip link add cata-gre-1 type gretap remote x.y.z.t
    ip link set dev cata-gre-1 up
    ip link set cata-gre-1 master cata-br-1
    ip link set dev cata-gre-1 type bridge_slave vlan_tunnel on
    bridge vlan add vid 10 dev cata-gre-1
    bridge vlan add dev cata-gre-1 vid 10 tunnel_info id 10
    ip link del vx10 2>/dev/null
    ip link add dev vx10 type vxlan external local dstport 4789
    ip link set vx10 up
    ip link set vx10 master cata-br-1
    ip link set dev vx10 type bridge_slave vlan_tunnel on
    bridge vlan add dev vx10 vid 10
    bridge vlan add dev vx10 vid 10 tunnel_info id 10
    ip link del va 2>/dev/null
    ip link add va type veth peer vb
    ip link set va up
    ip link set vb up
    ip link set vb master cata-br-1
    bridge vlan add dev vb vid 10 pvid untagged
    for dev in cata-gre-1 vx10 vb; do
            echo "===================== ${dev} ========="
            bridge fdb add 00:00:00:00:00:00 dev ${dev} vni 10 \
                    dst x.y.z.t self permanent
            bridge vlan show dev ${dev}
            bridge vlan tunnelshow dev ${dev}
    echo "====================="
    ip ad ad dev va