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Everything about nothing: April 2015

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Saturday, April 11, 2015. CentOS 7, Zimbra 8.6 and FirewallD. I just installed Zimbra 8.6 on a fresh CentOS 7. It seems that CentOS 7 uses FirewallD. Service by default instead of the old iptables and iptables6 scripts in /etc/init.d. Directory. Nevertheless I don't like when I see that someone recommends. To permanently enable each of the aforementioned services, use the following command:. Links to this post. Installing...

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Everything about nothing: January 2015

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Friday, January 9, 2015. Getting free disk space in Linux. While working on a script to have full Zimbra backup. S as many days in the past as possible, I was trying to automatically remove old backups based on the free space value. Basically, the idea was to remove directory by directory until free space reached some threshold. To find out free space on a disk is easy, use df(1). Dev/sda1 56267084 39311864 16938836 70% /.

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Everything about nothing: March 2014

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Sunday, March 23, 2014. Two or more applications listening on the same (IP, port) socket. Multiple applications to bind to a single port (under certain preconditions) but it doesn't work the way I described here. So, what you have to do is:. Open appropriate socket with socket() system call. Bind to interface using bind() system call. Attach filter to socket using setsockopt(). ICMP destination port unreachable message&#4...

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Everything about nothing: February 2015

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Saturday, February 28, 2015. Short Tip: Renaming log files to include date. I had a bunch of a log files in the format logfilename.N.gz. But I wanted to rename them into logfilename.YYYYMMDD.gz. Where YYYYMMDD is a date when the file was last modified. I did it using the following for loop:. For i in logfilename.*.gz. Mv -i $i logfilename.`date -r $i %Y%m%d`.gz. Command instead of date(1). Links to this post. TCP protocol...

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Everything about nothing: September 2014

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Wednesday, September 24, 2014. Anonymous paper reviews and threat of a legal action. I just stumbled on a news story. In which scientist claims that his career was severely damaged by anonymous comments on some of his works published on PubPeer. This is very interesting story to follow for several reasons. For a start, PubPeer is a site for a post publication review. Links to this post. Subscribe to: Posts (Atom). Scienti...

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Everything about nothing: June 2015

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Tuesday, June 16, 2015. How to fix weak DH key in Zimbra 7. I just had to fix a problem of weak DH keys. In Zimbra 7. Namely, Firefox and Chrome, after upgrade, don't want to connect. After a lot of search, the solution turned out to be easy. The key is to disable cipher suites that use DH keys. I managed to do that using the following commands:. Zmprov mcf zimbraSSLExcludeCipherSuites TLS DHE RSA WITH AES 128 CBC SHA.

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Everything about nothing: How to fix weak DH key in Zimbra 7

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Tuesday, June 16, 2015. How to fix weak DH key in Zimbra 7. I just had to fix a problem of weak DH keys. In Zimbra 7. Namely, Firefox and Chrome, after upgrade, don't want to connect. After a lot of search, the solution turned out to be easy. The key is to disable cipher suites that use DH keys. I managed to do that using the following commands:. Zmprov mcf zimbraSSLExcludeCipherSuites TLS DHE RSA WITH AES 128 CBC SHA.

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Everything about nothing: August 2014

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Saturday, August 23, 2014. It turns out that this was from the book Systems performance. Written by Brendan Gregg. So, I decided to replicate it here for a future reference:. Table 2.2: Example Time Scale of System Latencies. Level 1 cache access. Level 2 cache access. Level 3 cache access. Main memory access (DRAM, from CPU). Solid-state disk I/O (flash memory). 50 - 150 us. Internet: San Francisco to New York. Scientist...

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Everything about nothing: December 2014

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Monday, December 15, 2014. Incremental backup with rsync and cp with low disk demand. I just created very simple incremental backup solution for my Zimbra installation which efficiently uses disk space. The idea is simple. First, using rsync. I'm making a copy of existing Zimbra installation to another disk:. Rsync - delete - delete-excluded -a. I'm creating copy of this directory but which only consists of hard links.

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Everything about nothing: May 2014

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Random notes of what's on my mind. Additional materials you'll find on my homepage. Monday, May 5, 2014. This is a post about differences between uClibc. Libraries. Namely, OpenWRT. Is, what is its purpose and that the default C library on desktop and server Linux is glibc. Eglibc, or embedded glibc. Was developed with the intention of being source and binary compatible with glibc. That means that isn't necessary to recompile existing binary applications compiled for glibc in order to be possible to ...