Ejabberd XMPP server includes a SOCKS5 proxy, setting it up correctly is what makes the difference between fast or very slow file transfer operations. As per XEP-0065 file transfer is either peer-to-peer or mediated by a proxy server. In Conversation peer-to-peer transfer is done by converting the file in base64, split it in 4 kb chunks sent one at the time always awaiting first for the ACK of the precedent one; this makes the whole process painfully slow and bandwidth consuming. …

The latest version of DNScrypt-proxy does not use anymore a single configuration file (/etc/conf.d/dnscrypt-proxy) but instead completely relies on systemd. Configuration is now split in two different files. [root@arch ~]# cat /etc/systemd/system/multi-user.target.wants/dnscrypt-proxy.service --- [Unit] Description=DNSCrypt client proxy Requires=dnscrypt-proxy.socket [Install] Also=dnscrypt-proxy.socket WantedBy=multi-user.target [Service] Type=simple NonBlocking=true ExecStart=/usr/bin/dnscrypt-proxy \ --resolver-address=185.97.7.7:27015 \ --provider-name=2.dnscrypt-cert.fvz-rec-de-fra-01.dnsrec.meo.ws \ --provider-key=9FCC:EB74:6856:238D:AC57:428B:DE4F:D9C6:E736:5370:E9F9:5415:3BD3:6EBE:A8C2:FAFE \ --user=nobody …and… [root@arch ~]# cat /etc/systemd/system/dnscrypt-proxy.socket --- [Unit] Description=dnscrypt-proxy listening socket After=network.target [Socket] ListenStream=127.0.0.2:53 ListenDatagram=127.0.0.2:53 [Install] WantedBy=sockets.target

After some years of using Firefox (currently version 38.0.5) with Session Restore enabled (the browser saves all the tabs from the previous session and reload them at the next start-up) it started to act weird and freeze for around 10 seconds 3 or 4 times a day. This very annoying behavior is caused by the presence of multiple useless Session Restore files. To delete those files open a new tab and type about:support in the address bar, then in the Application Basics area click on the Open Directory button placed next to Profile Directory. …

The whole web is full of pseudo guides on how to properly - that is the key word here - configure Nginx to perform caching alongside with PHP-FPM, but every single one of them fails to mention some minor steps resulting in a borked half functioning implementation. For example, not a single one mention the necessity to edit /etc/php.ini and set session.use_cookies to 0. Too bad that without doing so caching with WordPress in combination with certain plugins or themes (for example MainWP or Enfold theme) is completely not working; the following headers get added to every HTTP response: …

Pacman as long as I know does not provide any method for sending an email notification when there are updates available. SSH into the Arch box just to find out if there are updates available is really annoying so I wrote a simple bash script to do the dirty work on my behalf. [root@arch ~]# cat /etc/cron.daily/check4updates.sh #!/bin/bash HOST=hostname DOMAIN=domain SUBJECT="System update: $HOST@$DOMAIN" EMAIL_ADDR="name@domain" ### Query pacman for available updates updates_raw=$(pacman -Syu <<< n) if echo $updates_raw | grep "there is nothing to do" then echo Everything is up to date else updates=${updates_raw#*Packages ([1-9])} ### extract packages update list up_raw=${updates%Total Download*} up=$(echo $up_raw | tr ' ' '\n') #echo -e "$up" > report. …

EXT4 is usually pretty good at keeping files fragmentation at minimum, but, sometimes, especially if dealing with really huge files, some fragmentation may actually occur. Luckily EXT4 supports online defragmentation, command fsck displays, among other things, fragmentation percentage: [root@fedora ~]$ fsck.ext4 -fvn /dev/sda1 e2fsck 1.42.12 (29-Aug-2014) Warning! /dev/sda1 is mounted. Warning: skipping journal recovery because doing a read-only filesystem check. Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information 429 inodes used (1. …

Yum provides a very useful package called yum-cron, its most publicized feature is the ability to enable yum to run nightly cron scheduled packages upgrades. I honestly don’t really think it is a good idea at all to let the system manage updates by himself but yum-cron can be used for another bunch of tasks, the most interesting one being: send an email if there are updates available. yum install yum-cron Configuration is actually pretty simple. …

Postfix configuration Install the required software: $ yum install postfix postgrey dovecot fail2ban spamassassin spamass-milter-postfix opendkim Create TLS certificate, key and CA authority (replace mail.domain.tld with a valid domain name): $ mkdir /etc/postfix/ssl $ cd /etc/postfix/ssl $ openssl genrsa -aes256 -out mail.domain.tld.key 4096 $ chmod 600 mail.domain.tld.key $ openssl req -sha256 -new -key mail.domain.tld.key -out mail.domain.tld.csr $ openssl x509 -sha256 -req -days 1825 -in mail.domain.tld.csr -signkey mail.domain.tld.key -out mail.domain.tld.crt $ openssl rsa -in mail. …