06 Mag 16 How to convert URI to query string parameters with mod_rewrite

You may need to convert URI levels to query string parameters, for example if want to be RESTful compliant with PHP.

Try this one:

RewriteEngine on
RewriteRule ^/(\w+)/(\w+)$ /path_of_index.php?lev1=$1&lev2=$2 [QSA,L]

In this case the first URI level will be converted to a query string parameter called lev1, while the second will be converted to a query string parameter called lev2, each one with the respective values.

For example, the uri /user/list will be passed to index.php and will become index.php?lev1=user&lev2=list

An eventual query string will be passed, eventually overriding lev1 and lev2 parameters.

Tags: apache, code, http, https, Linux, php, rewrite, server, sysadmin
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16 Apr 16 How to check if JCE Unlimited Strength policy is installed

JCE Unlimited Strength policy files are two files distributed by Oracle (this is for jdk8: http://www.oracle.com/technetwork/java/javase/downloads/jce8-download-2133166.html) that must be installed inside your JDK/jre/lib/security path if you want to unlock high strength cryptographic security for you java environment.

You need it for sure in a server environment outside USA.

If you don’t have this stuff installed, your jboss, tomcat, or any other server or client with a keylength higher than 1024 will not work.
To enable JCE Unlimited Strength you simply need to unzip the file downloaded from Oracle and copy US_export_policy.jar and local_policy.jar files in <JDK>/jre/lib/security.

You can check if JCE is unlimited using this command:

jrunscript -e ‘exit (javax.crypto.Cipher.getMaxAllowedKeyLength(“RC5”) >= 256);’; if [ $? -eq 1 ]; then echo “JCE Unlimited OK”; else echo “JCE NOT Unlimited”; fi

The jrunsctipt command is installed inside your JDK/bin path.

Tags: authority, cipher, https, java, jce, library, Linux, policy, server, sysadmin
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09 Apr 16 Getting in love with Docker Machine!!

Docker is becoming the “today standard” of lxs linux containers.
I think I will avoid learning Kubernetes to handle dockerized hosts, and I will study Docker Engine, Docker Swarm and Docker Machine and its REST APIs instead.

I started from here: https://docs.docker.com/machine/overview/

Tags: api, containers, docker, kubernetes, Linux, rest, server, swarm, sysadmin
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28 Nov 15 How to enable HTML5 video playback in firefox

If you use Mozilla Firefox and you want to view video streaming with HTML5 embedded players, you may need to enable some video functionality into the firefox configuration.
For some reason obscure to me Mozilla Firefox will not play some HTML5 based video streaming, and the embedded player will probably fall back to Adobe Flash based streaming (that is what I don’t want since it’s closed source and it’s a very insecure application).

For example, youtube has a HTML5 based player that you could choose to use instead of flv. You can verify and enable HTML5 based streaming functionality of your browser navigating to https://www.youtube.com/html5.

In my case (Firefox 64 bit on Linux Debian) the tabs “Media Source Extensions”, “MSE & H.264” and “MSE & WebM VP9” are disabled by default.

If you want to enable those functionalities simply write “about:config” into the firefox navigation bar.
You will be alerted to pay attention to not modify things or your warranty will be broken.
Just ignore the warning and proceed.

Now, if you did not already, switch the following configuration parameters to true:

media.fragmented-mp4.exposed
media.fragmented-mp4.ffmpeg.enabled
media.fragmented-mp4.gmp.enabled
media.mediasource.webm.enabled
media.mediasource.enabled

If you try to refresh the HTML5 based youtube player, you should hopefully have all video streaming tabs ready and enabled.
If you want, you can now switch the youtube default player to HTML5.

Tags: browser, codec, configuration, driver, firefox, html5, Linux, streaming, video
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24 Nov 15 HTTP request header from a query string parameter on apache reverse proxy

Suppose you have a apache httpd server working as a reverse proxy. Now suppose that this server has to set a HTTP request header called “token” to be attached to every request made to the backends, and that the header’s value must be copied from a query string parameter called “querytoken”.

This can be simply done with the help of mod_headers + mod_rewrite.

RewriteEngine On RewriteCond %{QUERY_STRING} (?:^|&)querytoken=([^&]+) RewriteRule (.*) - [E=QS_TOKEN:%1]

RequestHeader set token %{QS_TOKEN}e env=QS_TOKEN ProxyPass / http://your_backend/

Will your external client make a request like this:

GET /?querytoken=somestuff HTTP/1.0 Host: example

The request header that apache will do to the backend will be something like this:

GET /?token=somestuff HTTP/1.1 Host: 127.0.0.1:1234 token: somestuff X-Forwarded-For: 127.0.0.1 X-Forwarded-Host: example X-Forwarded-Server: myserver.linux Connection: Keep-Alive

The request header “token” with value “somestuff” is added to the request made to the backend.

Tags: apache, http, https, Linux, proxy, relaying, server, sysadmin
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04 Nov 15 Rescan iSCSI volume after resize on linux

If you need to resize a iSCSI volume you need to:

resize the volume on the iSCSI target (ietd)
rescan the volume on the iSCSI initiator (open-iscsi)
resize the fs, if any

I’ll skip the resize procedure on the target, because it depends on how it’s made (lvresize, dd, etc).

The procedure to rescan the volume on the initiator (open-iscsi) is very simple and can be accomplished online.

iscsiadm -m node -R

Then, you can grow the filesystem, if any (xfs_grofs, resize_reiserfs, resize2fs, depending on your fs type).

Tags: debian, disk, iSCSI, Linux, lun, lvm, server, sysadmin, volume
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30 Ott 15 How to check SSL/TLS protocol for a given server

If you need to check which SSL/TLS protocol version is implemented by your webserver, you can issue the following command:

dino@dam2knb:~$ echo | openssl s_client -connect 10.38.46.137:8443 2>&1 | grep Protocol Protocol : TLSv1.2

Tags: apache, debian, http, https, Linux, openssl, server, sysadmin, unix
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27 Gen 15 How to get the device mapper name associated to LVM logical volumes

This is how to get the device mapper name (dm-1, dm-2, etc) associated to each LVM logical volume:

lvdisplay|awk '/LV Name/{n=$3} /Block device/{d=$3; sub(".*:","dm-",d); print d,n;}'

Tags: device mapper, Linux, lvm, server, sysadmin
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15 Nov 14 Dump and restore block device data on the fly by the network

Sometimes you may need to copy data from a block device (or LVM logical volume or snapshot) from one server to another., but you don’t want to dump the image to disk, move to the other server, then import. You may need (or just want) to copy on the fly, transfering data on the net.

To do this, and have ETA on the operation you need the pv executable. The command nc is used to stream data on the network, while pigz is used to compress data (gzip uses just one CPU, while pigz uses all available CPU, and it’s much faster).

On the origin server (server1) you have a block device (lvm logical volume in this case) called /dev/vg0/vm-111-disk-1, while on the destination server (server2) you want to overwrite a LVM logical volume called /dev/vg0/vm-112-disk-1 with data coming from the origin server.
To do this, assuming the device is big 20GB, you may run those commands:

Server side (destination server, server2, ip 192.168.0.2):

nc -l -n -p 2102 -q 2 | pigz -d | pv -pre –size=20G | dd iflag=fullblock bs=512k of=/dev/vg0/vm-112-disk-1

Client side (origin server, server1, 192.168.0.1):

dd if=/dev/vg0/vm-111-disk-1 bs=512k | pv -pre –size=20G | pigz | nc -q 2 192.168.0.2 2102

Data will be read, compressed, transfered on the network on (port TCP 2102 on our case, from 192.168.0.1 to 192.168.0.2), uncompressed on the destination server and restored on disk, and you’ll have ETA and progress indication:

Output server side (destination server, server2):

root@server2 ~ # nc -l -n -p 2102 -q 2 | pigz -d | pv -pre –size=20G | dd iflag=fullblock bs=512k of=/dev/vg0/vm-112-disk-1
[71.2MB/s] [=========================================================================================================================================>] 100%
40960+0 records in
40960+0 records out
21474836480 bytes (21 GB) copied, 296.436 s, 72.4 MB/s

Output client side (origin server, server1):

root@server1 ~ # dd if=/dev/vg0/vm-111-disk-1 bs=512k | pv -pre –size=20G | pigz | nc -q 2 192.168.0.2 2102
[72.2MB/s]
[=========================================================================================================================================>]
100%
40960+0 records
40960+0 records out
21474836480 bytes (21 GB) copied, 283.531 s, 75.7 MB/s

Tags: dd, Linux, lvm, nc, server, sysadmin
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30 Ott 14 WPA2 connection without NetworkManager in Debian linux

This is a memo that I can use to remember how to enable WPA2 protected WiFI connections with debian without using NetworkManager.

All that you have to do is:

create the file /etc/wpa_supplicant/wpa_supplicant.conf with the following content:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=0
country=IT
ap_scan=2

network={
ssid=”My WiFI SSID”
psk=”mysupersecret password”
bssid=””
proto=RSN
key_mgmt=WPA-PSK
pairwise=CCMP TKIP
group=TKIP
}

if you want to set a static IP, add the following content to the file /etc/network/interfaces

iface wlan0 inet static
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
address 192.168.100.7
netmask 255.255.255.0
network 192.168.100.0
broadcast 192.168.100.255