This HowTo describes the procedure to patch & install djbdns in such a way that it writes & reads its DNS cache to/from hard disk, allowing it to survive computer reboots.
DJBdns <http://cr.yp.to/djbdns.html> are a set of tools to retrieve and publish Domain Name System (DNS) information.
Its main applications are a local DNS cache (dnscache) and an authoritarive DNS server (tinydns).
[Posted at <http://ubuntuforums.org/showthread.php?p=9064333>]
1. Prepare to install
# Install tools used to build djbdns
sudo aptitude install -R build-essential devscripts
cd $(mktemp -d) ; # create a temp dir and cd to it
apt-get source djbdns ; sudo apt-get build-dep djbdns # get source & deps
cd $(ls -d djbdns-*/) # cd djbdns-1.05/
# Ubuntu 10.04: patch with djbdns-dumpcache.patch
# we use the patch, proposed by riemann <http://riemann.fmi.uni-sofia.bg/docs/djbdns-dumpcache.html>, to enable save/load dns cache to/from hard disk and to fix the SIGPIPE bug.
# get riemann patch
wget http://riemann.fmi.uni-sofia.bg/prog...umpcache.patch
# make it Debian friendly
sed -i 's|djbdns-1.05\/|djbdns-1.05.orig\/|;s|djbdns-1.05_new\/|djbdns-1.05\/|' djbdns-dumpcache.patch
sed -i '/diff -/d;s/"14400:/"300:/' djbdns-dumpcache.patch # disk dump every 5m
mv -v djbdns-dumpcache.patch debian/diff/0003-djbdns-dumpcache.diff
sed -i '/>conf-cc/s| -O2|& -DDUMPCACHE|' debian/rules # enable riemann patch
# fix bugs in: debian/rules & debian/control, make them process only djbdns code
sed -i '/cat FILES/,/done/d ; /^dbndns\//,/-stamp/d ; /# dbndns/,/done/d ; s/build-stamp \\$/build-stamp/ ; /dbndns\/\*/d ; s|[ \t]\+dbndns[^ \t]\+||g ; /DIRDBN/d' debian/rules ; sed -i '/^Package:.*dbndns/,/remote servers./d' debian/control
# fix bugs in: dnscache-run.postinst, dnscache-run.postrm
tee debian/dnscache-run.postinst.new <<-\EOA
#!/bin/sh
set -e
test "$1" = 'configure' || exit 0
mv -f /etc/sv/dnscache/root/servers/@ /etc/dnsroots.global
test -x /etc/sv/dnscache && rm -fr /etc/sv/dnscache
test -x /etc/service/dnscache && rm -fr /etc/service/dnscache
test -x /etc/dnscache && rm -fr /etc/dnscache
dnscache-conf Gdnscache Gdnslog /etc/sv/dnscache
(cd /etc/sv/dnscache/log/;rm -fr main;ln -sfn /var/log/dnscache/ main)
update-service --add /etc/sv/dnscache
test -z "$2" || exit 0
chown Gdnslog:adm /var/log/dnscache
EOA
mv debian/dnscache-run.postinst.new debian/dnscache-run.postinst
# fix bugs in: djbdns-1.05/debian/dnscache-run.postrm
tee debian/dnscache-run.postrm.new <<-\EOA
#!/bin/sh
set -e
test "$1" = 'purge' || exit 0
svc -dx /etc/sv/dnscache /etc/sv/dnscache/log || :
rm -rf /etc/sv/dnscache
rm -rf /var/lib/supervise/dnscache /var/lib/supervise/dnscache.log
rm -rf /var/log/dnscache || :
for i in Gdnscache Gdnslog; do
! getent passwd $i >/dev/null ||
userdel $i || :
done
test -f /etc/dhcp3/dhclient.conf && sed -i '/^prepend.*127.0.0.1/s/^/#/' /etc/dhcp3/dhclient.conf > /dev/null 2>&1
sed -i '/dnscache-run/d;/127.0.0.1/d' /etc/resolv.conf > /dev/null 2>&1
EOA
mv debian/dnscache-run.postrm.new debian/dnscache-run.postrm
# customize maintainer data
sed -i '/^Maintainer/s/: .*/: dummy <dummy@example.com>/' debian/control ; grep '^Maintainer\|^Uploaders\|XSBC-Original-Maintainer' debian/control
# update debian/changelog
(export DEBFULLNAME='dummy';export DEBEMAIL='dummy <dummy@example.com>';dch -i "apply debian/diff/0003-djbdns-dumpcache.diff patch from <http://riemann.fmi.uni-sofia.bg/docs/djbdns-dumpcache.html>. This patch enables save/load dns cache to/from hard disk and fixes the SIGPIPE bug).") ; head -n 9 debian/changelog
# build the modified djbdns & dnscache-run .deb packages
(export DEBFULLNAME='dummy';export DEBEMAIL='dummy@example.com';debuild -i -us -uc);
2. install patched djbdns app.
# If reinstalling: first purge djbdns, daemontools, ucspi-tcp
cp -vaf /etc/dnscache/root/dump/data ~/ # if available
sudo /sbin/stop svscan
sudo aptitude -y purge dnscache-run djbdns daemontools-run daemontools ucspi-tcp
test -f /etc/dhcp3/dhclient.conf && sudo sed -i '/^prepend.*127.0.0.1/s/^/#/' /etc/dhcp3/dhclient.conf
sudo sed -i '/dnscache-run/d;/127.0.0.1/d' /etc/resolv.conf
sudo rm -fr /var/lib/supervise /etc/dnscache* /etc/service /etc/sv
# install the new .deb's
sudo aptitude install daemontools daemontools-run ucspi-tcp
sudo dpkg -i djbdns_1.05-*.deb && sudo aptitude hold djbdns
sudo dpkg -i dnscache-run_1.05-*.deb && sudo aptitude hold dnscache-run
sudo sh -c "chown Gdnscache.Gdnscache ~/data;cp -vaf ~/data /etc/dnscache/root/dump/;chattr -i /etc/resolv.conf"
pgrep dhclient >/dev/null && sudo sed -i '/prepend.*127.0.0.1/s/^#//' /etc/dhcp3/dhclient.conf # if using dhcp
pgrep dhclient >/dev/null || { echo '# Generated by dnscache-run' >~/resolv.conf.'{tmp}'.$$ ; echo 'nameserver 127.0.0.1' >>~/resolv.conf.'{tmp}'.$$ ; cat /etc/resolv.conf >>~/resolv.conf.'{tmp}'.$$ ; sudo mv -f ~/resolv.conf.'{tmp}'.$$ /etc/resolv.conf; } # if NOT using dhcp
# Now start djbdns service
sudo /sbin/start svscan # start service
pgrep dhclient >/dev/null && { sudo dhclient;sleep 2; } # if using dhcp
pgrep dhclient >/dev/null || sudo /etc/init.d/networking restart # if static ip
################################
#### PROCEDURE ENDS HERE ####
################################
3. 3. Test & control
## check status
sudo svstat /etc/sv/* /etc/sv/*/log # service status
ps -ef | sed '/!d/d;/readproctitle/!d' # service errors
(cd /etc/sv/dnscache/env 2>&1>/dev/null && grep "^" * ) # env & config
(cd /etc/sv/dnscache/root/ip 2>&1>/dev/null && ls -1 ) # authorised clients
# show root servers: (cd /etc/sv/dnscache/root/servers 2>&1>/dev/null && grep "^" /dev/null * )
# IF dnscache CACHE LOGGING enabled:
# Open 2 terminals side-by-side (press ALT+F2 and enter: gnome-terminal)
# in terminal 1: check dnscache working:
tail -f /etc/sv/dnscache/log/main/current
# in terminal 2: compare "Query time" from both runs:
dig google.com | grep time && sleep 3
dig google.com | grep time
dnsip $(dnsqr ns . | sed -e '/answer/!d;s/\(.*\)NS \(.*\)/\2/')
dnsip www.fsf.org
dnsqr any cnn.com
dnsq a www.google.com 192.203.230.10
env DNSCACHEIP=208.67.222.222 dnsqr a www.google.com
## control cache
sudo svc -a /etc/sv/dnscache ;# PATCHED dump cache
sudo svc -h /etc/sv/dnscache ;# PATCHED (re)load cache
sudo svc -t /etc/sv/dnscache # PATCHED dump & exit
sudo svc -d /etc/sv/dnscache # DOWN
sudo svc -u /etc/sv/dnscache # UP
4. Customize
# change riemann's dumpcache write to disk interval (in seconds)
sudo sed -i 's/^.*:/300:/' /etc/dnscache/env/DUMPCACHE # modify 300
# change log profile
cat /etc/sv/dnscache/log/run
#!/bin/sh
exec setuidgid Gdnslog multilog t ./main
# change to: multilog t '-*' +'*stats *' ./main
# ...
# change to: s+d+s: multilog t '-*' +'*stats *' +'*dump *' +'*slurp *' ./main
#
sudo cp /etc/sv/dnscache/log/run /etc/sv/dnscache/log/run.{NEW}
sudo sed -i '/exec/d' /etc/sv/dnscache/log/run.{NEW}
## multilog t '-*' '+* fatal: *' ./main
echo "exec setuidgid Gdnslog multilog t '-*' '+*stats *' '+*dump *' '+*slurp *' ./main" | sudo tee -a /etc/sv/dnscache/log/run.{NEW}
cat /etc/sv/dnscache/log/run.{NEW}
sudo mv /etc/sv/dnscache/log/run.{NEW} /etc/sv/dnscache/log/run
cat /etc/sv/dnscache/log/run
sudo svc -h /etc/sv/dnscache/log ;# restart log service
# restore default
#
sudo sed -i 's/multilog.*/multilog t \.\/main/' /etc/sv/dnscache/log/run
# update dns root servers list
dnsip $(dnsqr ns . | sed -e '/answer/!d;s/\(.*\)NS \(.*\)/\2/') | sudo tee /etc/dnsroots.global ; sudo cp -v /etc/dnsroots.global /etc/dnscache/root/servers/@'{NEW}' && sudo mv /etc/dnscache/root/servers/@'{NEW}' /etc/dnscache/root/servers/@
# add a procedure to CLEAR the service error log
sudo rm -rf /etc/sv/clear /var/lib/supervise/clear
sudo mkdir -p /etc/sv/clear /var/lib/supervise/clear
sudo touch /etc/sv/clear/down && sudo chmod a-w /etc/sv/clear/down
sudo tee /etc/sv/clear/run <<-\EOA
#!/bin/sh
# to check for service errors execute:
# ps -ef | sed '/!d/d;/readproctitle/!d'
# to clear the service error log execute:
# sudo svc -o /etc/sv/clear
yes '' | head -400 | tr '\n' .
EOA
sudo chmod +x /etc/sv/clear/run
(cd /etc/;sudo ln -sv sv/clear dnscacheclear)
sudo update-service --add /etc/sv/clear;sleep 3 # man update-service
sudo svstat /etc/sv/* /etc/sv/*/log # check djb tools status
ps -ef | sed '/!d/d;/readproctitle/!d'
# sudo update-service --remove /etc/sv/clear
# sudo rm -rf /etc/sv/clear /var/lib/supervise/clear
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