dnswithtor

#!/usr/bin/env bash
##############################################################################
#
# dnssecwithtor
# -------------------
# Configures Unbound, socat, and Tor, for resolving, validating, and caching
# DNS requests through the Tor network.
#
# see https://labs.nic.cz/page/993/dnssec-validation-over-tor--linux-/
#
# @author Isis Agora Lovecruft, 0x2cdb8b35
# @date 25 August 2012
# @version 0.0.1
#
##############################################################################

TOR_SOCKS_PORT="9050"

PATH_UNBOUND=`which unbound`
PATH_SOCAT=`which socat`
PATH_TOR=`which tor`
PATH_DIG=`which dig`

OARC_RES="149.20.64.20"
CZ_NIC_RES="217.31.204.130"

function check_deps ()
{
    FAILZ=""
    ## XXX TODO offer to get dependencies for user
    test -x $PATH_UNBOUND || FAILZ="unbound "
    test -x $PATH_SOCAT || FAILZ=$FAILZ"socat "
    test -x $PATH_TOR || FAILZ=$FAILZ"tor "
    test -x $PATH_DIG || FAILZ=$FAILZ"bind-utils "

    if [[ "$FAILZ" != "" ]] ; then
        echo "do \"apt-get install $FAILZ"
        exit 1
    fi
}

function explain_all_of_the_things () {
    echo "DNS resolution will follow this chain:"
    echo ""
    echo "QUERY" 
    echo " \\-> localhost:53 "
    echo "        \\-> unbound -> 0.0.0.0:5353 -> 127.0.0.1:5353 "
    echo "                                               / "
    echo "             socat <---------------------------  "
    echo "              \\-> local SOCKS4a proxy -> 127.0.0.1:$TOR_SOCKS_PORT "
    echo "                                               / "
    echo " tor <-----------------------------------------  "
    echo "  \\ "
    echo "   \\-> guard " 
    echo "          \\-> middle "
    echo "                  \\-> exit -> ?.?.?.?:53 <--> recursive DNS resolve"
    echo "                                    / "
    echo "                      exit <--------  "
    echo "             middle <-/ "               
    echo "      guard <-/ "
    echo " tor <-/ "
    echo "  \\     "
    echo "   \\-> local SOCKS4a proxy   "
    echo "          \\-> socat         "
    echo "                \\-> unbound "
    echo "                      \\-> validation -> local DNS cache "
    echo "                                               / "
    echo "RESPONSE <-------------------------------------  "
    echo ""
    echo "Totally not confusing at all, right?"
    echo ""
    echo ""
}

function check_dns ()
{
    ## Check that recursive, validated DNS resolves correctly without unbound

    MSG1="Testing DNS resolution over TCP to recursive validating resolver"

    echo "$MSG1 OARC at $OARC_RES ... "; echo;
    ANS1=`dig +tcp +dnssec labs.nic.cz @$OARC_RES  | grep -C 1 ';; flags'`
    echo "$ANS1"; echo;
    CHECK1=$(echo $ANS1 | grep "NOERROR" | wc -l)
    if [[ "$CHECK1" == "1" ]] ; then
        echo "The resolver at $OARC_RES is working correctly."
    else
        echo "The resolver at $OARC_RES either could not be reached or something else went wrong!"
        echo "Please debug your unbound installation and network settings."
        echo "Exiting ..."
        exit 1
    fi

    echo "$MSG1 labs.nic.cz at $CZ_NIC_RES"
    ANS2=`dig +tcp +dnssec labs.nic.cz @$OARC_RES  | grep -C 1 ';; flags'`
    echo "$ANS2"; echo;
    CHECK2=$(echo $ANS2 | grep "NOERROR" | wc -l)
    if [[ "$CHECK2" == "1" ]] ; then
        echo "The resolver at $CZ_NIC_RES is working correctly."
    else
        echo "The resolver at $CZ_NIC_RES either could not be reached or something else went wrong!"
        echo "Please debug your unbound installation and network settings."
        echo "Exiting ..."
        exit 1
    fi
}

function check_tor ()
{
    echo "Checking that Tor is currently running ... "
    CHECK5=$(pgrep tor | wc -l)
    if [[ "$CHECK5" == "0" ]] ; then
        echo "Process for Tor not found ..."
        echo "Tor is not currently running ..."
        echo "Starting Tor ..."
        if test -x /etc/init.d/tor ; then
            sudo /etc/init.d/tor start
        else
            echo "Could not find init script for Tor ..."
            echo "Exiting ..."
            exit 1
        fi
    else
        echo "Tor process found ..."
        echo "Tor is currently running ..."
    fi
}

function check_socat ()
{
    if [ "$(pidof socat && echo $?)" != 0 ] ; then
        echo "Starting socat tunnel ..." 
        coproc socat TCP4-LISTEN:5353,bind=localhost,reuseaddr,fork SOCKS4A:localhost:149.20.64.20:53,socksport=$TOR_SOCKS_PORT
    fi
}

function kill_socat ()
{
    if [ "$(pidof socat >/dev/null 2>&1 && echo $?)" = 0 ] ; then
        kill $(pidof socat)
    fi
}


function check_socat_conn_tor ()
{
    echo "Testing that the socat tunnel is connecting to Tor ..."
    ANS4=`dig -p 5353 +tcp +dnssec labs.nic.cz @localhost`
    CHECK4=$(echo  $ANS4 | grep "NOERROR" | wc -l)
    if [[ "$CHECK4" == "0" ]] ; then
        echo "Socat was unable to talk to Tor ..."
        echo "We currently believe that your SOCKS port is $TOR_SOCKS_PORT."
        echo "Please check your torrc to make sure this is correct, if your"
        echo "torrc says otherwise, then edit the top line of this script "
        echo "to match your torrc."
        echo ""
        echo "Exiting ..."
    else
        echo "Socat tunnel is connected to Tor, and a DNS request was completed:"
        echo "$ANS4"
        echo ""
    fi
}

function check_unbound ()
{
    echo "Checking that unbound is currently running ... "
    CHECK3=`pgrep unbound | wc -l`
    if [[ "$CHECK3" == "0" ]] ; then
        echo "Process for unbound not found ..."
        echo "Unbound is not currently running ..."
        echo "Starting unbound ..."
        if test -x /etc/init.d/unbound ; then
            sudo /etc/init.d/unbound start
        else
            echo "Could not find init script for unbound ..."
            echo "Exiting ..."
            exit 1
        fi
    else
        echo "Unbound process found ..."
        echo "Unbound is currently running ..."
    fi
}

function check_dnssec ()
{
    echo "Testing DNS resolution of a DNSSEC query through unbound instance ..."
    ANS6=`dig +dnssec labs.nic.cz @localhost`
    CHECK6=$(echo  $ANS6 | grep "NOERROR" | wc -l)
    if [[ "$CHECK6" == "0" ]] ; then
        echo "Unbound appears to not be working ..."
        echo "Although, we are about to backup the current config for unbound"
        echo "and continue with a new config...should we continue doing so?"
        select yn in "yes" "no" ; do
            case $yn in
                yes ) 
                    break
                    ;;
                no )
                    echo "Exiting ..."
                    exit 0
                    ;;
                * )
                    exit 1
                    ;;
            esac
        done
    else
        echo "Unbound resolved the query correctly ..."
        echo "Checking that DNSSEC answer was validated according to root anchor ..."
        CHECK7=$(echo  $ANS6 | grep "flags.*ad" | wc -l)
        if [[ "$CHECK7" != "1" ]] ; then
            echo "DNSSEC flag was missing from query results!"
            echo "Maybe you haven't yet configured the root anchor?"
            echo "See http://unbound.net/documentation/howto_anchor.html"
        else
            echo "DNSSEC flags present in query results ..."
            echo "DNSSEC validation check passed ..."
        fi
    fi
}

function backup_unbound_conf ()
{
    MAYBECONF=$(locate -l 1 unbound.conf)
    MAYBEBACK=$MAYBECONF".orig.bak"
    DINOCONF="/etc/unbound/unbound.dinosaur"
    if test -x $MAYBECONF ; then
        if [[ "$MAYBECONF" == "/etc/unbound/unbound.conf" ]] ; then
            echo "Backing up $MAYBECONF to $MAYBEBACK ..."
            sudo cp $MAYBECONF $MAYBEBACK
        fi
    else
        echo "Couldn't find /etc/unbound/unbound.conf ..."
        echo "Hum. Do you have some strange configuration settings for unbound?"
        echo "We weren't able to backup /etc/unbound/unbound.conf, so we're"
        echo "going to go ahead and create the new config in its place ..."
    fi    
}

function make_unbound_conf ()
{
    echo "Creating new unbound.conf file ..."
    sudo touch $DINOCONF && \
        sudo chmod a+rw $DINOCONF
    cat > $DINOCONF<<EOF
## generated by DiNoSaur script
server:
        interface: 127.0.0.1
        port: 53
        hide-identity: yes
        hide-version: yes
        harden-glue: yes
        ## because Tor only speaks TCP
        tcp-upstream: yes

forward-zone:
        ## forward every query to our socat tunnel to Tor
        name: "."
        forward-addr: 0.0.0.0@5353
EOF
    sudo chmod a-w $DINOCONF
    sudo cp $DINOCONF /etc/unbound/unbound.conf
}

if [[ "$#" == "0" ]] ; then
    check_deps
    check_dns
    explain_all_of_the_things
    check_tor
    check_socat
    check_socat_conn_tor
    check_unbound
    check_dnssec
    backup_unbound_conf
    make_unbound_conf
    echo "Restarting unbound ..."
    sudo /etc/init.d/unbound restart
    echo "Checking DNSSEC query resolution through unbound -> socat -> Tor ..."
    check_dnssec
else
    ## it wouldn't be a script without it...
    cat <<"EOF"
 ____________________________________
| DiNoSaur! Recursive, validating,   |
| caching, DNSSEC-enabled resolution |
| through Unbound, socat, and Tor\!  |
 ------------------------------------
\                             .       .
 \                           / `.   .' "
  \                  .---.  <    > <    >  .---.
   \                 |    \  \ - ~ ~ - /  /    |
         _____          ..-~             ~-..-~
        |  (A)|   \~~~\.'                    `./~~~/
       ---------   \__/                        \__/
      .'  O    \     /               /       \  "
     (_____,    `._.'               |         }  \/~~~/
      `----.          /       }     |        /    \__/
            `-.      |       /      |       /      `. ,~~|
                ~-.__|      /_ - ~ ^|      /- _      `..-'
                     |     /        |     /     ~-.     `-. _  _  _
                     |_____|        |_____|         ~ - . _ _ _ _ _>

EOF
fi