Linux

Installing CentOS

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Установка CentOS LVM не используем По умолчанию на небольшой диск (< 2TB) Linux пытается установить MBR. Чтобы выбрать EUFI (GPT) либо выбираем ее как основной способ загрузки в BIOS, либо выбираем в качестве первого загрузочного устройства USB-флэшку, с которой проводим инсталляцию, тогда программа установки сама переключится на EUFI. Если используется EUFI, дополнительно к стандартным разделам […]

Linux

Unix monitoring and audit

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https://cisofy.com/lynis/ Lynis is an open source security auditing tool. Used by system administrators, security professionals, and auditors, to evaluate the security defenses of their Linux and Unix-based systems. It runs on the host itself, so it performs more extensive security scans than vulnerability scanners. It is also the client in our Lynis Enterprise offering. https://www.tecmint.com/linux-server-health-monitoring-script/  

Linux

Linux multihome host with rule based routing

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http://jensd.be/468/linux/two-network-cards-rp_filter rp_filter Since RHEL 6 (and CentOS 6), asymmetric routing doesn’t work anymore out of the box. The cause of the issue is a change in the default value for kernel parameter rp_filter. Rp_filter stands for reverse path filtering. The reverse path filter will check if the source of a packet that was received on a certain interface […]

Unix

Battery learning on LSI controller

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https://web.archive.org/web/20130729085738/http://inside.godaddy.com/learning-deal-learning/ Many RAID controllers, like our Dell PERC cards, go through a battery learning cycle which calibrates the capacity of the battery to ensure it does not unexpectedly fail. For us, this cycle occurs every 90 days. When a battery learning cycle begins, it fully charges, discharges, and then charges again, realigning the true capacity of the […]

Linux

Working with local sendmail queue

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https://www.cyberciti.biz/tips/howto-postfix-flush-mail-queue.html Under Postfix MTA, just enter the following command to flush the mail queue: # postfix flush OR # postfix -f To see mail queue, enter: # mailq OR #  sendmail -bp To remove all mail from the queue, enter: # postsuper -d ALL To remove all mails in the deferred queue, enter: # postsuper […]

Linux

InitV and systemd parctical notes

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Nicely written reference https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/sect-Managing_Services_with_systemd-Unit_Files.html Short cheat shit List services: # chkconfig –list # systemctl list-units This will show any unit that systemd loaded or attempted to load, regardless of its current state on the system. # systemctl list-units –all # systemctl list-units –all –state=inactive # systemctl list-units –type=service Since systemd will only read units that it […]

Solaris

XSCF cheat sheet

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http://thegeekdiary.com/most-commonly-used-xscf-commands-cheat-sheet/ The eXtended System Control Facility Unit (XSCFU) is a service processor that operates and administrates both midrange servers. The XSCFU diagnoses and starts the entire server, configures domains, offers dynamic reconfiguration, as well as detects and notifies various failures. The XSCFU enables standard control and monitoring function through network. Using this function enables starts, […]

Linux

Sudoers syntax

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http://unix.stackexchange.com/questions/18877/what-is-the-proper-sudoers-syntax-to-add-a-user In the following sudo entry: superadm ALL=(ALL) ALL there are four fields: The first one specifies a user that will be granted privileges for some command(s). The second one is rarely used. It’s a list of hostnames on which this sudo entry will be effective. On standard setups only one host is relevant (localhost) […]

Solaris

Format command hangs

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https://support.symantec.com/en_US/article.TECH225180.html Cause The ‘format’ utility has a new feature beginning in Solaris 10 6/06 Operating System called ‘in use checking’. This feature is enabled by default. Solution Any time the ‘format’ utility is run on the disk, it performs many verification/checks on the disk itself (does it contain a slice that is mounted, is it […]

Linux

vmstat output explained

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Table 11-4 Output From the vmstat Command Category Field Name Description procs Reports on the following: r The number of kernel threads in the dispatch queue b The number of blocked kernel threads that are waiting for resources w The number of swapped out LWPs that are waiting for processing resources to finish memory Reports on usage of […]