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Author: halfgaar

Halfgaar is Wiebe. Wiebe is a contributing author on this weblog. He also has a lot of stuff (such as long, in-depth articles) on his personal website.

Wiebe works at YTEC, where he is a senior developer of customer-specific tailor-made software (“klantspecifieke maatwerk software“) for clients in a few select markets: wholesale, printing and healthcare.

Configuring Nagios to check a HTTP host

Nagios is an elaborate piece of software to monitor hosts and services. I will explain a bit how you can configure nagios to monitor an HTTP service. I'm assuming your nagios setup already has the default config files generic-host_nagios2.cfg and generic-service_nagios2.cfg, which tell nagios how to monitor hosts and services. Read More »

Disable Zimbra’s duplicate mail detection

Zimbra can discard duplicates of incoming mail. This has certain advantages, but for us, where different people use the same account with different identities, this prevents a message from being delivered to multiple virtual inboxes. Read More »

Lowering Bayes score for Zimbra’s Spamassassin config

The Spamassassin config in Zimbra has a very high default score for bayes matching of 99, 95, 90, etc, percent. A mail with subject and body "test" or "asdfaewf a" is often marked as 99% bayes, even though the spamfilter has seen no training mail. This is absurd. Read More »

Configuring fetchmail to deliver to Zimbra with custom header added

I needed to fetch mail from a POP3 account and deliver it to a Zimbra account. Because I'm doing this for multiple POP3 accounts, I want to add a header which I can use in Zimbra to filter. This is what we made: Read More »

Fixing spamassassin rule in Zimbra

Spamassassin has had a bug for a while, marking any mail from 2010 and later as spam because it's from "far into the future". This was very crudely done as this regexp: /20[1-9][0-9]/. Because of that, almost all mail from 2010 onward is marked as spam. Read More »

Scanning the entire network for machines with nmap

You can easily scan the entire network for machine presence with nmap: nmap -sP -v -v 192.168.1.* Read More »

Set proper origin domain for Zimbra server

(This turned out not to be how I fixed it. I just configured exim and /etc/mailname as I do always and that fixed it. However, exim does not run as the SMTP server listening on port 25, that is the postfix installed by Zimbra. I don't know how and if this exim configuration conflicts with zimbra.) Read More »

Changing lost MySQL root password

When you don't know the current mysql root password and you want to change it, do this: /etc/init.d/mysql stop mysqld --skip-grant-tables & mysql -p use mysql; update user set password=PASSWORD("NEW-ROOT-PASSWORD") where User='root'; flush privileges; quit; killall mysqld /etc/init.d/mysql start Read More »

Convenient iptables rules

Here are some convenient iptables rules. This first list is for not allowing anything in, accept packets that come back from outgoing connections, complicated related traffic like FTP, everything from the localhost, ICMP (ping and stuff) and SSH. It also sets the default policy to DROP. This you would use on a machine connected directly to the internet. Read More »

My custom Linux environment

On every machine that I install, I need a custom environment. At the very basic, I need screen and bash customizations. I will attempt to keep this blog post up-to-date with my most recent config. Read More »