unimportant – Page 4

apache2 – redirect from http to https with some source-ip-based exceptions

2021-08-02 by .pQd

i was migrating a server from http to https. while header-based redirect worked for most of the clients, for some – i had to allow for a transition period where some configuration / code had to be adjusted. here’s the config that responds with 302 redir to most of the http requests, but for those ... Read More

switching source of SVN replica

2021-07-152021-07-15 by .pQd

i have svn replica that follows in near-real-time a master server using below run every few seconds: i had to change url of the source server; to reconfigure the the replica i’ve done:

changing source url of the svn repository replica

2021-04-202021-04-20 by .pQd

i have bunch of svn read-only replicas. they were created using: replication [ fetching of earlier not downloaded revisions ] is done via: to check from which url my replica repo fetches updates: to change it – run: that’s it – next execution of svnsync will fetch the data from the new origin url based ... Read More

fiddler returning “HTTP/1.1 502 Fiddler – Connection Failed” for HTTPs requests replied / made with it?

2021-04-152021-04-15 by .pQd

i’ve been using fiddler tool for ages. recently i’ve noticed most of my attempts of sending new requests fail with: solution? tools > options > [x] capture HTTPS CONNECTs > [x] Decrypt HTTPS traffic > protocols: enter there tls1.2 once it’s set you can un-tick [x] capture.

“Verify your Kindle document” for pdfs self-mailed to my kindle

2021-04-052021-04-05 by .pQd

whenever i travel i like to use kindle for reading some articles that i’ve earlier collected. for collecting i use a simple PHP script with rich text editor that allows me to copy & paste content and then mail it to my kindle address. recently i’ve started getting requests from Amazon to approve each document ... Read More

xiaomi robot vaccuum disassembly

2021-03-062021-03-06 by .pQd

i have 1st gen xiaomi mi robot vacuum cleaner. it’s been serving very well for the past 3 years. this video was very helpful with disassembly when i had to replace the main sucking motor fan: https://www.youtube.com/watch?v=wdDSBgJ1kRM i had to replace a fan and bought https://www.aliexpress.com/item/4000804127893.html instead of https://www.aliexpress.com/item/4000259186760.html ; not an exact fit but ... Read More

clickhouse

2021-02-212023-01-05 by .pQd

clickhouse is a column oriented OLAP database. i’ve started using it about half a year ago. i’m impressed. earlier i’ve read about it on percona’s blog but did not fully grasp how performant it was. i’ve tried it when i wrestling with MariaDB’s query planner on table with ~100M rows got me tired and each ... Read More

supermicro server getting stuck on “loading initial ramdisk”

2021-01-302021-02-19 by .pQd

i had a quite puzzling moment today when a server refused to boot up after routine maintenance. order of events: datacenter technician has taken server down and added Mellanox 25Gbit network card server booted up cleanly with Debian Buster and aged kernel 4.19.0-6 i’ve rebooted the server again and changed cpu performance settings in bios ... Read More

supermicro IPMI – mounting iso image via samba

2021-01-30 by .pQd

reminder for my self in case i need to do it again, relevant for X11DDW-NT and likely – other their platforms: log-in to the IPMI web interface, go to virtual media > CD-ROM image, provide: share host – ip or hostname of samba server. for instance: 10.1.2.3 paht to image – backlash share name backslash ... Read More

letting dbeaver talk with manticoresearch

2021-01-162021-01-16 by .pQd

here’s what i did to get dbeaver 7.3.2 + oracle’s JDBC mysql-connector-java-8.0.17.jar work with manticoresearch 3.5.4: /etc/manticoresearch/manticore.conf, under searchd: in dbeaver – new connection using oracle’s JDBC driver as above, under data editor – set ResultFetchSize to 0 to prevent errors like this: when i initially tried to get it working with JDBC driver from ... Read More

live-resizing KVM VM disk backed by qcow2 file

2021-01-102021-01-10 by .pQd

let’s say you have KVM VM with Linux and you’d like to resize its qcow2-backed disk without shutting down VM.

black hole, somewhere in the internet, swallowing UDP packets

2020-12-052022-01-26 by .pQd

UDP packets sent from specific source port, with public source IP address do not reach specific destination port of the public destination IP address. changing any of the parameters [ usually source port ] – fixes the issue. i’ve observed this phenomenon multiple times for long-running OpenVPN and Wireguard VPNs encapsulating encrypted traffic in UDP ... Read More

using dedicated server from hetzner

2020-09-252025-08-15 by .pQd

4 months ago i’ve started renting a dedicated server at https://www.hetzner.com/ and – so far – i’m quite happy with the service. i’ve picked cheapest suitable hardware from their auctions, after a month of trouble-free usage i’ve switched to quarterly billing. then server has crashed few times with “shutting down cpus with nmi” kernel messages. ... Read More

resizing btrfs on luks on mdadm raid10

2020-09-18 by .pQd

one of my KVM VMs keeps data on BTRFS on top of encrypted LUKS drive. that drive is a block device passed from virtualization server to VM… a block device which is mdadm software RAID10. below – steps taken to resize it.

detecting duplicate network packets from linux command line

2020-07-302020-08-18 by .pQd

while going down the rabbit hole of bed network performance at work we’ve narrowed the problem cause to duplicate packets showing up on a specific segment of leased metro Ethernet service. tshark filter helped us to see when duplicates occurred on monitored link we’ve got pair of computers – A and B connected at both ... Read More

backup via ssh-tunneled connection

2020-05-022020-05-02 by .pQd

in one context i need to pull backup from server C to server A. normally i’d use rsync with direct ssh connection as a transport method. in this particular case C is not directly reachable from A, so i need to use ssh tunneling to connect from A to C via jump-host B: public ssh ... Read More

apache2 – reverse proxy with sticky sessions and fail-over

2020-02-092020-02-09 by .pQd

i needed to set up apache2 as a reverse proxy that will forward requests to few backends. yes – i know that there are better tools to do it – like haproxy or nginx – but in this case apache2 was preferred for the simplicity of the setup. requirements: sticky sessions – in normal conditions ... Read More

guacamole under Debian

2019-12-012019-12-01 by .pQd

Apache Guacamole is a clientless remote desktop gateway – with it you can access RDP-enabled Windows PC using ordinary web browser and HTTP[S]. below – notes taken while setting it up under Debian 10.

useful network-related tools

2019-11-022019-11-02 by .pQd

internet-wide scanners: https://censys.io/ https://www.shodan.io/ ssl: https://www.ssllabs.com/ smtp: https://www.mail-tester.com/ dns: http://dns.squish.net/

upgrading firmware on Intel’s SATA SSD drives behind Dell’s h730p RAID

2019-10-132019-11-03 by .pQd

fetch Intel_SSD_Data_Center_Tool from here. the zip archive contained, among other, .deb for 64 bit OS – that worked for me under debian stretch. to see drives run: to upgrade the firmware where 0 corresponds to the Index of drive returned by the first command the same likely works for other LSI/Avago cards – no matter ... Read More