REST API for Pokemon

A new global trend has just started on using mobile app Pokemon GO to search for favourite monster with augmented reality features and encouraging app users around the world to walk more for a better health condition.

By looking at the maps of activities, I was stunned but also excited. This seems to be the next wave  in Big Data world. How can we miss it?

Pokeapi - The RESTful Pokémon API v2 Beta has been released. For whatever reason, they are limited to 300 requests per resource per IP address.

Check and see what's the next killer app you can create from this.

URL:
https://pokeapi.co

Eclipse IDE autocomplete for JavaScript and PHP

To enable autocomplete feature for language like JavaScript and PHP in your Eclipse project:

Locate and open .project file under Parent folder of your project within Eclipse IDE

Add two lines as below:

org.eclipse.wst.jsdt.core.jsNature
org.eclipse.php.core.PHPNature

Restart Eclipse IDE and you should see autocomplete suggestions while typing your code in *.js or *.php files.

Upgrade ESXi from 5.5 Update 3 to 6.0 Update 2

The good thing in ESXi 5.5 is the upgrade process can be done via SSH terminal. This eliminates the CD-ROM burning process and carries out the entire upgrade remotely from my laptop. As mentioned before, it's not always the direct process for version upgrade in ESXi infrastructure.

I was looking for the HP custom version of offline bundle (namely "HPE Custom Image for VMware ESXi 6.0 U2 Offline Bundle") for the HP machines which supposedly gathered all the drivers it needs for installing ESXi onto HP machines. You may need to download different custom version or official offline bundle for other machines which are supported otherwise.

URL:
https://my.vmware.com/group/vmware/details?downloadGroup=OEM-ESXI60U2-HPE&productId=491

After uploading the zip file onto ESXi box's datastore via vSphere client, with the following command I just got this error message on my ESXi console:

~ #
~ # esxcli software vib update -d /vmfs/volumes/datastore1/VMware-ESXi-6.0.0-2494585-depot.zip
[DependencyError]
 VIB VMware_bootbank_esx-base_6.0.0-2.34.3620759 requires vsan >= 6.0.0-2.34, but the requirement cannot be satisfied within the ImageProfile.
 VIB VMware_bootbank_esx-base_6.0.0-2.34.3620759 requires vsan << 6.0.0-2.35, but the requirement cannot be satisfied within the ImageProfile.
 Please refer to the log file for more details.
~ #
~ #

Honestly, ESXi 5.5 doesn't quite like the new VIB module named vsan. In other words, it doesn't have vsan in the current profile. That's why the path for vid update failed. So, let's go through the upgrade process with profile update option.

To list the current profile name, use the following command:

~ # esxcli software sources profile list -d /vmfs/volumes/datastore1/VMware-ESXi-6.0.0-2494585-depot.zip
Name                                 Vendor                      Acceptance Level
-----------------------------------  --------------------------  ----------------
HPE-ESXi-6.0.0-Update2-600.9.5.0.48  Hewlett Packard Enterprise  PartnerSupported

This may give different result on every single ESXi box, so you may need to take note of your own box for the actual name of image profile. Here, we have a profile name called "HPE-ESXi-6.0.0-Update2-600.9.5.0.48".

Now, it's time to proceed the upgrade:

~ #
~ # esxcli software profile update -p HPE-ESXi-6.0.0-Update2-600.9.5.0.48 -d /vmfs/volumes/datastore1/VMware-ESXi-6.0.0-2494585-depot.zip
.
.

And then I got the followings:

Update Result
   Message: The update completed successfully, but the system needs to be rebooted for the changes to be effective.
   Reboot Required: true
   VIBs Installed: BRCM_bootbank_net-tg3_3.137l.v60.1-1OEM.600.0.0.2494585, EMU_bootbank_elxnet_10.7.110.13-1OEM.600.0.0.2768847, EMU_bootbank_ima-be2iscsi_10.7.110.10-1OEM.600.0.0.2159203, EMU_bootbank_lpfc_10.7.110.4-1OEM.600.0.0.2768847, EMU_bootbank_scsi-be2iscsi_10.7.110.10-1OEM.600.0.0.2159203, HPE_bootbank_amsHelper_600.10.4.0-22.2494585, HPE_bootbank_conrep_6.0.0.01-01.00.7.2494585, HPE_bootbank_hpbootcfg_6.0.0.02-02.00.6.2494585, HPE_bootbank_hpe-build_600.9.5.0.48-2494585, HPE_bootbank_hpe-esxi-fc-enablement_600.2.5.20-2494585, HPE_bootbank_hpe-ilo_600.10.0.0.26-1OEM.600.0.0.2494585, HPE_bootbank_hpe-smx-provider_600.03.10.00.13-2768847, HPE_bootbank_hponcfg_6.0.0.04-00.14.4.2494585, HPE_bootbank_hpssacli_2.40.13.0-6.0.0.1854445, HPE_bootbank_hptestevent_6.0.0.01-01.00.5.2494585, Hewlett-Packard_bootbank_char-hpcru_6.0.6.14-1OEM.600.0.0.2159203, Hewlett-Packard_bootbank_hpnmi_600.2.3.14-2159203, Hewlett-Packard_bootbank_scsi-hpdsa_5.5.0.48-1OEM.550.0.0.1331820, Hewlett-Packard_bootbank_scsi-hpsa_6.0.0.116-1OEM.600.0.0.2494585, Intel_bootbank_intelcim-provider_0.5-1.6, Intel_bootbank_net-i40e_1.3.45-1OEM.550.0.0.1331820, Intel_bootbank_net-igb_5.3.1-1OEM.550.0.0.1331820, Intel_bootbank_net-ixgbe_4.1.1.1-1OEM.550.0.0.1331820, MEL_bootbank_nmlx4-core_3.1.0.0-1OEM.600.0.0.2348722, MEL_bootbank_nmlx4-en_3.1.0.0-1OEM.600.0.0.2348722, MEL_bootbank_nmst_4.0.2.1-1OEM.600.0.0.2295424, QLogic_bootbank_misc-cnic-register_1.712.70.v60.1-1OEM.600.0.0.2494585, QLogic_bootbank_net-bnx2_2.2.5k.v60.1-1OEM.600.0.0.2494585, QLogic_bootbank_net-bnx2x_2.712.70.v60.3-1OEM.600.0.0.2494585, QLogic_bootbank_net-cnic_2.712.70.v60.3-1OEM.600.0.0.2494585, QLogic_bootbank_net-nx-nic_6.0.643-1OEM.600.0.0.2494585, QLogic_bootbank_net-qlcnic_6.1.191-1OEM.600.0.0.2494585, QLogic_bootbank_qlnativefc_2.1.30.0-1OEM.600.0.0.2768847, QLogic_bootbank_scsi-bnx2fc_1.712.70.v60.5-1OEM.600.0.0.2494585, QLogic_bootbank_scsi-bnx2i_2.712.70.v60.2-1OEM.600.0.0.2494585, VMWARE_bootbank_mtip32xx-native_3.8.5-1vmw.600.0.0.2494585, VMware_bootbank_ata-pata-amd_0.3.10-3vmw.600.0.0.2494585, VMware_bootbank_ata-pata-atiixp_0.4.6-4vmw.600.0.0.2494585, VMware_bootbank_ata-pata-cmd64x_0.2.5-3vmw.600.0.0.2494585, VMware_bootbank_ata-pata-hpt3x2n_0.3.4-3vmw.600.0.0.2494585, VMware_bootbank_ata-pata-pdc2027x_1.0-3vmw.600.0.0.2494585, VMware_bootbank_ata-pata-serverworks_0.4.3-3vmw.600.0.0.2494585, VMware_bootbank_ata-pata-sil680_0.4.8-3vmw.600.0.0.2494585, VMware_bootbank_ata-pata-via_0.3.3-2vmw.600.0.0.2494585, VMware_bootbank_block-cciss_3.6.14-10vmw.600.0.0.2494585, VMware_bootbank_cpu-microcode_6.0.0-0.0.2494585, VMware_bootbank_ehci-ehci-hcd_1.0-3vmw.600.2.34.3620759, VMware_bootbank_emulex-esx-elxnetcli_10.2.309.6v-0.0.2494585, VMware_bootbank_esx-base_6.0.0-2.34.3620759, VMware_bootbank_esx-dvfilter-generic-fastpath_6.0.0-0.0.2494585, VMware_bootbank_esx-tboot_6.0.0-2.34.3620759, VMware_bootbank_esx-ui_1.0.0-3617585, VMware_bootbank_esx-xserver_6.0.0-0.0.2494585, VMware_bootbank_ipmi-ipmi-devintf_39.1-4vmw.600.0.0.2494585, VMware_bootbank_ipmi-ipmi-msghandler_39.1-4vmw.600.0.0.2494585, VMware_bootbank_ipmi-ipmi-si-drv_39.1-4vmw.600.0.0.2494585, VMware_bootbank_lsi-mr3_6.605.08.00-7vmw.600.1.17.3029758, VMware_bootbank_lsi-msgpt3_06.255.12.00-8vmw.600.1.17.3029758, VMware_bootbank_lsu-hp-hpsa-plugin_1.0.0-1vmw.600.0.0.2494585, VMware_bootbank_lsu-lsi-lsi-mr3-plugin_1.0.0-2vmw.600.0.11.2809209, VMware_bootbank_lsu-lsi-lsi-msgpt3-plugin_1.0.0-1vmw.600.0.0.2494585, VMware_bootbank_lsu-lsi-megaraid-sas-plugin_1.0.0-2vmw.600.0.11.2809209, VMware_bootbank_lsu-lsi-mpt2sas-plugin_1.0.0-4vmw.600.1.17.3029758, VMware_bootbank_lsu-lsi-mptsas-plugin_1.0.0-1vmw.600.0.0.2494585, VMware_bootbank_misc-drivers_6.0.0-2.34.3620759, VMware_bootbank_net-e1000_8.0.3.1-5vmw.600.0.0.2494585, VMware_bootbank_net-enic_2.1.2.38-2vmw.600.0.0.2494585, VMware_bootbank_net-forcedeth_0.61-2vmw.600.0.0.2494585, VMware_bootbank_net-vmxnet3_1.1.3.0-3vmw.600.2.34.3620759, VMware_bootbank_nmlx4-rdma_3.0.0.0-1vmw.600.0.0.2494585, VMware_bootbank_nvme_1.2.0.27-4vmw.550.0.0.1331820, VMware_bootbank_ohci-usb-ohci_1.0-3vmw.600.0.0.2494585, VMware_bootbank_rste_2.0.2.0088-4vmw.600.0.0.2494585, VMware_bootbank_sata-ahci_3.0-22vmw.600.2.34.3620759, VMware_bootbank_sata-ata-piix_2.12-10vmw.600.0.0.2494585, VMware_bootbank_sata-sata-nv_3.5-4vmw.600.0.0.2494585, VMware_bootbank_sata-sata-promise_2.12-3vmw.600.0.0.2494585, VMware_bootbank_sata-sata-sil24_1.1-1vmw.600.0.0.2494585, VMware_bootbank_sata-sata-sil_2.3-4vmw.600.0.0.2494585, VMware_bootbank_sata-sata-svw_2.3-3vmw.600.0.0.2494585, VMware_bootbank_scsi-aacraid_1.1.5.1-9vmw.600.0.0.2494585, VMware_bootbank_scsi-adp94xx_1.0.8.12-6vmw.600.0.0.2494585, VMware_bootbank_scsi-aic79xx_3.1-5vmw.600.0.0.2494585, VMware_bootbank_scsi-fnic_1.5.0.45-3vmw.600.0.0.2494585, VMware_bootbank_scsi-ips_7.12.05-4vmw.600.0.0.2494585, VMware_bootbank_scsi-megaraid-mbox_2.20.5.1-6vmw.600.0.0.2494585, VMware_bootbank_scsi-megaraid-sas_6.603.55.00-2vmw.600.0.0.2494585, VMware_bootbank_scsi-megaraid2_2.00.4-9vmw.600.0.0.2494585, VMware_bootbank_scsi-mptsas_4.23.01.00-9vmw.600.0.0.2494585, VMware_bootbank_scsi-mptspi_4.23.01.00-9vmw.600.0.0.2494585, VMware_bootbank_uhci-usb-uhci_1.0-3vmw.600.0.0.2494585, VMware_bootbank_vsan_6.0.0-2.34.3563498, VMware_bootbank_vsanhealth_6.0.0-3000000.3.0.2.34.3544323, VMware_bootbank_xhci-xhci_1.0-3vmw.600.2.34.3620759, VMware_locker_tools-light_6.0.0-2.34.3620759
   VIBs Removed: Broadcom_bootbank_net-tg3_3.137l.v55.1-1OEM.550.0.0.1331820, Emulex_bootbank_elxnet_10.5.121.7-1OEM.550.0.0.1331820, Emulex_bootbank_ima-be2iscsi_10.5.65.7-1OEM.550.0.0.1331820, Emulex_bootbank_lpfc_10.5.39.0-1OEM.550.0.0.1331820, Emulex_bootbank_scsi-be2iscsi_10.5.65.7-1OEM.550.0.0.1331820, Hewlett-Packard_bootbank_char-hpcru_5.5.6.6-1OEM.550.0.0.1198610, Hewlett-Packard_bootbank_char-hpilo_550.9.0.2.3-1OEM.550.0.0.1198610, Hewlett-Packard_bootbank_hp-ams_550.10.3.0-15.1198610, Hewlett-Packard_bootbank_hp-build_550.9.4.26-1198610, Hewlett-Packard_bootbank_hp-conrep_5.5.0.1-0.0.8.1198610, Hewlett-Packard_bootbank_hp-esxi-fc-enablement_550.2.4.6-1198610, Hewlett-Packard_bootbank_hp-smx-provider_550.03.09.00.15-1198610, Hewlett-Packard_bootbank_hpbootcfg_5.5.0.02-01.00.5.1198610, Hewlett-Packard_bootbank_hpnmi_550.2.3.5-1198610, Hewlett-Packard_bootbank_hponcfg_5.5.0.4.4-0.3.1198610, Hewlett-Packard_bootbank_hpssacli_2.30.6.0-5.5.0.1198611, Hewlett-Packard_bootbank_hptestevent_5.5.0.01-00.01.4.1198610, Hewlett-Packard_bootbank_scsi-hpdsa_5.5.0.46-1OEM.550.0.0.1331820, Hewlett-Packard_bootbank_scsi-hpsa_5.5.0.114-1OEM.550.0.0.1331820, Intel_bootbank_intelcim-provider_0.5-1.4, Intel_bootbank_net-i40e_1.2.48-1OEM.550.0.0.1331820, Intel_bootbank_net-igb_5.2.10-1OEM.550.0.0.1331820, Intel_bootbank_net-ixgbe_3.21.4.3-1OEM.550.0.0.1331820, QLogic_bootbank_misc-cnic-register_1.712.50.v55.1-1OEM.550.0.0.1331820, QLogic_bootbank_net-bnx2_2.2.5j.v55.3-1OEM.550.0.0.1331820, QLogic_bootbank_net-bnx2x_2.712.50.v55.6-1OEM.550.0.0.1331820, QLogic_bootbank_net-cnic_2.712.50.v55.6-1OEM.550.0.0.1331820, QLogic_bootbank_net-nx-nic_5.5.643-1OEM.550.0.0.1331820, QLogic_bootbank_net-qlcnic_5.5.190-1OEM.550.0.0.1331820, QLogic_bootbank_qlnativefc_1.1.55.0-1OEM.550.0.0.1331820, QLogic_bootbank_scsi-bnx2fc_1.712.50.v55.7-1OEM.550.0.0.1331820, QLogic_bootbank_scsi-bnx2i_2.712.50.v55.4-1OEM.550.0.0.1331820, VMware_bootbank_ata-pata-amd_0.3.10-3vmw.550.0.0.1331820, VMware_bootbank_ata-pata-atiixp_0.4.6-4vmw.550.0.0.1331820, VMware_bootbank_ata-pata-cmd64x_0.2.5-3vmw.550.0.0.1331820, VMware_bootbank_ata-pata-hpt3x2n_0.3.4-3vmw.550.0.0.1331820, VMware_bootbank_ata-pata-pdc2027x_1.0-3vmw.550.0.0.1331820, VMware_bootbank_ata-pata-serverworks_0.4.3-3vmw.550.0.0.1331820, VMware_bootbank_ata-pata-sil680_0.4.8-3vmw.550.0.0.1331820, VMware_bootbank_ata-pata-via_0.3.3-2vmw.550.0.0.1331820, VMware_bootbank_block-cciss_3.6.14-10vmw.550.0.0.1331820, VMware_bootbank_ehci-ehci-hcd_1.0-3vmw.550.0.0.1331820, VMware_bootbank_esx-base_5.5.0-3.71.3116895, VMware_bootbank_esx-dvfilter-generic-fastpath_5.5.0-0.0.1331820, VMware_bootbank_esx-tboot_5.5.0-2.33.2068190, VMware_bootbank_esx-ui_0.0.2-0.1.3357452, VMware_bootbank_esx-xlibs_5.5.0-0.0.1331820, VMware_bootbank_esx-xserver_5.5.0-0.0.1331820, VMware_bootbank_ipmi-ipmi-devintf_39.1-4vmw.550.0.0.1331820, VMware_bootbank_ipmi-ipmi-msghandler_39.1-4vmw.550.0.0.1331820, VMware_bootbank_ipmi-ipmi-si-drv_39.1-4vmw.550.0.0.1331820, VMware_bootbank_lsi-mr3_0.255.03.01-2vmw.550.3.68.3029944, VMware_bootbank_lsi-msgpt3_00.255.03.03-1vmw.550.1.15.1623387, VMware_bootbank_misc-drivers_5.5.0-3.68.3029944, VMware_bootbank_mtip32xx-native_3.3.4-1vmw.550.1.15.1623387, VMware_bootbank_net-be2net_4.6.100.0v-1vmw.550.0.0.1331820, VMware_bootbank_net-e1000_8.0.3.1-3vmw.550.0.0.1331820, VMware_bootbank_net-enic_1.4.2.15a-1vmw.550.0.0.1331820, VMware_bootbank_net-forcedeth_0.61-2vmw.550.0.0.1331820, VMware_bootbank_net-vmxnet3_1.1.3.0-3vmw.550.2.39.2143827, VMware_bootbank_ohci-usb-ohci_1.0-3vmw.550.0.0.1331820, VMware_bootbank_rste_2.0.2.0088-4vmw.550.1.15.1623387, VMware_bootbank_sata-ahci_3.0-22vmw.550.3.68.3029944, VMware_bootbank_sata-ata-piix_2.12-10vmw.550.2.33.2068190, VMware_bootbank_sata-sata-nv_3.5-4vmw.550.0.0.1331820, VMware_bootbank_sata-sata-promise_2.12-3vmw.550.0.0.1331820, VMware_bootbank_sata-sata-sil24_1.1-1vmw.550.0.0.1331820, VMware_bootbank_sata-sata-sil_2.3-4vmw.550.0.0.1331820, VMware_bootbank_sata-sata-svw_2.3-3vmw.550.0.0.1331820, VMware_bootbank_scsi-aacraid_1.1.5.1-9vmw.550.0.0.1331820, VMware_bootbank_scsi-adp94xx_1.0.8.12-6vmw.550.0.0.1331820, VMware_bootbank_scsi-aic79xx_3.1-5vmw.550.0.0.1331820, VMware_bootbank_scsi-fnic_1.5.0.4-1vmw.550.0.0.1331820, VMware_bootbank_scsi-ips_7.12.05-4vmw.550.0.0.1331820, VMware_bootbank_scsi-megaraid-mbox_2.20.5.1-6vmw.550.0.0.1331820, VMware_bootbank_scsi-megaraid-sas_5.34-9vmw.550.3.68.3029944, VMware_bootbank_scsi-megaraid2_2.00.4-9vmw.550.0.0.1331820, VMware_bootbank_scsi-mptsas_4.23.01.00-9vmw.550.3.68.3029944, VMware_bootbank_scsi-mptspi_4.23.01.00-9vmw.550.3.68.3029944, VMware_bootbank_uhci-usb-uhci_1.0-3vmw.550.0.0.1331820, VMware_bootbank_xhci-xhci_1.0-2vmw.550.3.68.3029944, VMware_locker_tools-light_5.5.0-3.68.3029944
   VIBs Skipped: Avago_bootbank_scsi-mpt2sas_15.10.06.00-1OEM.550.0.0.1331820, Hewlett-Packard_bootbank_scsi-hpvsa_5.5.0.100-1OEM.550.0.0.1331820, QLogic_bootbank_scsi-bfa_3.2.5.0-1OEM.550.0.0.1331820, QLogic_bootbank_scsi-qla4xxx_644.6.05.0-1OEM.600.0.0.2494585, VMware_bootbank_ima-qla4xxx_2.02.18-1vmw.600.0.0.2494585, VMware_bootbank_net-e1000e_3.2.2.1-1vmw.600.1.26.3380124, VMware_bootbank_net-mlx4-core_1.9.7.0-1vmw.600.0.0.2494585, VMware_bootbank_net-mlx4-en_1.9.7.0-1vmw.600.0.0.2494585

Such a long passage reporting how things are done. It's successful anyway. You need to reboot the ESXi box to make changes effective.

NB: You may need to use boot option like "noIOMMU" during the reboot process.

To enable noIOMMU option via SSH, try this command:

> esxcli system settings kernel set –setting=noIOMMU -v TRUE

Hanging on "Initialising IOV" message after ESXi 5.5 Upgrade

For my experience in ESXi infrastructure, it's always not easy to upgrade in one go.

Simply add boot options at bootup screen by pressing Shift + O, enter additional parameter "noIOMMU" at the end of the boot string. Then press ENTER key to proceed bootup procedures:

.
[Boot options...] noIOMMU
.

Once ESXi box is started successfully, you may want to apply persistent settings by SSH remotely into the box and issue the following command:

~ #
~ #
~ # esxcli system settings kernel set --setting=noIOMMU -v TRUE
~ #
~ #

This makes noIOMMU option survives ongoing reboots;-)

Access ATAPI DVD writer on VMware ESXi 4.x Windows Guest VM

To access the physical DVD writer on Windows Guest VM, there is no alternative but setting up a SCSI device for this.

IDE passthrough on CD/DVD-ROM device seems not to be really promising as I have tried through different ESXi 4.x boxes.

Finally, I found this way to get through this. You need to open up vSphere interface at a remote machine for monitor and control. You also need a remote desktop session connected to the target Windows Guest VM for checking read/write access on the target physical DVD drive.

Using remote VMware vSphere interface, it is easy to add new SCSI device for physical DVD drive. Before adding new SCSI device, you may want to shutdown Windows guest VM first. 

Once SCSI DVD device is added to Guest VM's profile, you may start the VM again to see if the device is detected.

When you can login to Windows Guest VM, it's time to try on remote vSphere interface by clicking CD/DVD-ROM device icon to connect to host physical device. You should see the device raw ID as shown in the selection list for choice on vSphere interface. Once connected, the physical SCSI DVD drive should be ready to go for Read & Write operations on your Windows Guest VM.

Practical way to tackle WiFi dropout and slow performance issue in OS X El Capitan

There is a couple of occasions that I need to do have an upgrade on Mac OS X. Chances are I completely forget those tweaking tips and hope things will be resolved in next version. Something like WiFi connection tweaking I can remind from the forum. An explanation can help me remind those things I should do every single time when I need to do an OS X upgrade.

We can find all kinds of topics regarding WiFi dropout issue on OS X and someone may suggest standard procedure to get around this. For WiFi settings, Apple would like to stick to standard MTU size at 1500 bytes for Ethernet network. But, why?

With WiFi connection, we can do a ping test like this:

$
$
$ ping -D -s 1500 google.com
PING google.com (203.5.76.246): 1500 data bytes
ping: sendto: Message too long
ping: sendto: Message too long

Note:
Option -D suppresses fragmentation for the packet (force to transmit whole packet at a time)
Option -s 1500 specify the packet size, i.e., 1500 bytes

Problem is there is an overhead added on top of packet size for every transmission. That is why we get 'Message too long' responses from there.

To rectify this problem, let's do the math:

Optimum MTU size = Packet size + Overhead

What about the overhead? The overhead would be 28 bytes because 20 bytes are reserved for the IP header and 8 bytes must be allocated for the ICMP Echo Request header.

So, maximum packet size permitted in each network packet is actually:

Optimum MTU size = Non-fragmented Packet size +  28 bytes

Here we say MTU size will theoretically be 1500. Packet size allowed would be

(1500 -28)=1472 bytes

But, is it practical? Let's test this.

To test this magic number, issue the following command in Terminal:

$
$
$ ping -D -s 1472 google.com
PING google.com (203.5.76.246): 1472 data bytes
1480 bytes from 203.5.76.246: icmp_seq=0 ttl=56 time=7.787 ms
1480 bytes from 203.5.76.246: icmp_seq=1 ttl=56 time=4.838 ms
1480 bytes from 203.5.76.246: icmp_seq=2 ttl=56 time=4.360 ms
1480 bytes from 203.5.76.246: icmp_seq=3 ttl=56 time=6.184 ms

Packets are now transmitted successfully with this payload (1472). Therefore, we can be sure the optimum MTU payload size would be 1500 (luckily a theoretical value this time) just for this particular WiFi network.

With no fragmentation happening, each packet should be theoretically transmitted as a whole and not broken in parts. This can improve the network speed effectively in an ideal signal condition.

Just remind that the size of payload can be different across various locations and wireless routers. You might need to find the smallest optimum payload which sits within the size range of successful transmission for most networks you'll be connecting, either at home or office. Try stepping down the value until you find transmission works for all the networks you have tried.

Apply this payload value in Network settings panel and hopefully it'll help reduce the number of WiFi dropout and improve the WiFi network speed.

Secure network daemons using TCP wrapper on Ubuntu

As many blogposts point out that network daemon like sshd can be protected via configurations in two files /etc/hosts.deny and /etc/hosts.allow.

What about httpd or nignx? They provide web services to the network clients and it seems that TCP wrapper doesn't restrict access to these daemons.

TCP wrapper would only be effective when the network daemon has dependency over library like libwrap.so. To check whether a daemon relies on libwrap.so library. Issue the following command will do the job:

$ ldd /usr/sbin/sshd | grep libwrap
libwrap.so.0 => /lib/.../libwrap.so.0 (0xb55a5000) 

Daemon like sshd does rely on this TCP wrapper library so can be managed by chainging configurations in both /etc/hosts.deny and /etc/hosts.allow.

However, ldd test failed to display TCP wrapper dependency for daemon like httpd and nginx. This explains why TCP wrapper poses no action over these two daemon even with similar configurations.

Just keep in mind that checking dependency library for the daemons before trying to secure them using TCP wrapper.

Nginx php-fpm security.limit_extension issue

Just found something weird while tweaking the configurations in Nginx PHP-FPM. URL via https suddenly went offline and the server log shows something as follows:

[error] 18292#0: *1 FastCGI sent in stderr: "Access to the script '/usr/share/nginx/html' has been denied (see security.limit_extensions)", client: x.x.x.x, server: localhost, request: "GET /index.php HTTP/1.1", host: "xxx.net"

Although people suggest to turn off security.limit_extensions by setting it to nothing, it really raise me a bit of security concern.

It ends up there's one line in the config file /etc/nginx/sites-enabled/default which causes the error:

#
#
fastcgi_param PATH_TRANSLATED $document_root$fastcgi_path_info;

Comment it out is okay while the .php page loads fine if it's changed to something else:

# Fix for missing params and blank php page display problems
include fastcgi_params;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param PATH_INFO          $fastcgi_path_info;
#fastcgi_param PATH_TRANSLATED    $document_root$fastcgi_path_info;
fastcgi_param PATH_TRANSLATED    $document_root$fastcgi_script_name;

Reloading nginx server again and things are loaded up properly!

Adding Fail2Ban UFW Portscan Filter on Ubuntu

To further prevent portscan from bad bots around the world, there's a way of making use of Fail2Ban filter.

Assuming Fail2Ban is in place, edit the config file as below;

$ sudo nano /etc/fail2ban/jail.local

Add new section in jail.local:

[ufw-port-scan]

enabled   = true
ignoreip  = 127.0.0.1/8
port      = all
filter    = ufw-port-scan
banaction = ufw
logpath   = /var/log/ufw.log
maxretry  = 20

Create new filter as follows:

$ sudo nano /etc/fail2ban/filter.d/ufw-port-scan.conf

Add new lines in ufw-port-scan.conf:

[Definition]
failregex = .*\[UFW BLOCK\] IN=.* SRC=
ignoreregex =

Create ban action config file as follows:

$ sudo nano /etc/fail2ban/action.d/ufw.conf

Add new lines in ufw.conf:

[Definition]
actionstart =
actionstop =
actioncheck =
actionban = ufw insert 1 deny from  to any
actionunban = ufw delete deny from  to any

Have a service restart and it's good to go.

$ sudo service fail2ban restart

It's possible to run a test for the regex rule as well:

$ fail2ban-regex /var/log/ufw.log '.*\[UFW BLOCK\] IN=.* SRC='

Then you might get some results back like these:

Running tests

=============

Use   failregex line : .*\[UFW BLOCK\] IN=.* SRC=

Use         log file : /var/log/ufw.log.1

Results

=======

Failregex: 163 total

|-  #) [# of hits] regular expression

|   1) [163] .*\[UFW BLOCK\] IN=.* SRC=

`-

Ignoreregex: 0 total

Date template hits:

|- [# of hits] date format

|  [163] MONTH Day Hour:Minute:Second

`-

Lines: 163 lines, 0 ignored, 163 matched, 0 missed

Nginx PHP-FPM display blank page for .PHP file on Ubuntu

Setting up new Nginx instance wasn't a funny thing as stated on most blogposts while it display blank page during startup. This is annoying when people set things up from scratches.

First thing first:

Check whether PHP-FPM is running:
$ ps -aux | grep php-fpm --color

$
$ ps -aux | grep php-fpm --color
root      1898  0.0  1.8 209928 18992 ?        Ss   11:48   0:00 php-fpm: master process (/etc/php/7.0/fpm/php-fpm.conf)                      
www-data  1900  0.0  0.6 210060  6660 ?        S    11:48   0:00 php-fpm: pool www                                                            
www-data  1901  0.0  0.5 210060  6088 ?        S    11:48   0:00 php-fpm: pool www   

Also, you may notice that running processes may be owned by someone else, like nginx, apache or whatsoever. Make sure user/group setting in php-fpm config file is referring to the same user/group as set in Nginx config file, like www-data/www-data.

Default location of php-fpm 7.0 config file:

/etc/php/7.0/fpm/pool.d/www.conf

Default location of Nginx config file:
/etc/nginx/sites-available/default

Back to the question about why nginx displays a balnk page instead? Let's take a look at the Nginx config file:

...
...
server {
        ...
        location ~ \.php$ {
                try_files $uri =404;
                fastcgi_split_path_info ^(.+\.php)(/.+)$;
                fastcgi_cache  microcache;
                fastcgi_cache_key $scheme$host$request_uri$request_method;
                fastcgi_cache_valid 200 301 302 30s;
                fastcgi_cache_use_stale updating error timeout invalid_header http_500;
                fastcgi_pass_header Set-Cookie;
                fastcgi_pass_header Cookie;
                fastcgi_ignore_headers Cache-Control Expires Set-Cookie;
                fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
                fastcgi_index index.php;
                include fastcgi_params;
                # Fix for missing params and blank php page display problems
                fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
                fastcgi_param PATH_TRANSLATED $document_root$fastcgi_script_name;

        }
}

The line "include fastcgi_params" actually refers to the file /etc/nginx/fastcgi_params which has various fastcgi_param variables initialized when calling. Unfortunately, two important variables went missing leading to an unknown blank page when startup.

They are SCRITP_FILENAME and PATH_TRANSLATED. Add them back to Nginx config file and PHP things execute again!

Ref: https://www.narga.net/avoid-nginx-wordpress-blank-page/