Marudai – tkáčsky stroj z Japonska

Marudai je tkáčsky stroj z Japonska. V Japonsku ich majú niekoľko typov. Tento je ale asi najjednoduchší na vyrobenie a dajú sa na ňom vyrábať zaujímavé vzorované šnúrky. Technika pletenia šnúrok sa zase volá kumihimo. O tejto technike dokonca nájdete knihy aj v slovenčine.

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PowerDNS – GSQLBackend lookup query:Attempt to bind more parameters than query has

PowerDNS is a very good DNS nameserver, but debugging is sometimes very hard. I just add some records to my zone and zone stops working: server doesn’t respond to DNS queries.

Here is error from syslog:

2018-03-28T23:59:14+02:00 my [err] [pdns] Exception building answer packet for (All data was not consumed) sending out servfail
 2018-03-28T23:59:30+02:00 my [err] [pdns] Backend reported permanent error which prevented lookup (GSQLBackend lookup query:Attempt to bind more parameters than query has: SELECT content,ttl,prio,type,domain_id,disabled,name,auth FROM records WHERE disabled=0 and name=? and domain_id=?), aborting

Tracing of pdns told me the following exception:

$ strace -s 4096 -f -e send,recv,read,write,sendmsg -p `pidof /usr/sbin/pdns_server-instance`
[pid 12801] send(3, "<27>Mar 29 01:09:08 pdns[12791]: Exception building answer packet for (All data was not consumed) sending out servfail\0", 137, MSG_NOSIGNAL) = 137

After few hours of googling, debugging, removing records etc. I have found:

$ pdnsutil check-zone
[Error] Following record had a problem: " IN SOA 2018032808 21600 7200 1209600 3600 "
[Error] Error was: All data was not consumed
Checked 14 records of '', 1 errors, 0 warnings.

Did you notice extra space at the end of record? After removing extra space problem get solved.

I have added the following crontab job to prevent problems in the feature:

@daily pdnsutil check-all-zones | grep Error

Firewall rule to allow access to windows updates

When you try to install Windows updates for the first time (e.g. you buy a new computer with Windows 8.1 preinstalled), windows doesn’t start to download updates unless you permit UDP connection to port 3544.

Here is the firewalling rule for your linux firewall:

iptables -A FORWARD -d -p udp -m udp --dport 3544 -m conntrack --ctstate NEW -j ACCEPT

Here we go!

Howto make sure nagstamon is running on your desktop

nagstamon_header_logoAdd the following line to your (desktop user, not root) crontab:

*/5 * * * * [ -z "`pidof -x /usr/bin/nagstamon`" ] && DISPLAY=:0.0 /usr/bin/nagstamon &

This will start nagstamon and make sure user doesn’t closes them. Tricky is configuration of connection to you Xserver / graphical environment. But solution is simple: set $DISPLAY environment variable to :0.0 value, which means ‚use the first desktop running on localhost‘.

Did you know ‚xauth list‘ command?