DD-WRT startup adblock scripts based on https://pastebin.com/aySi7RhY

ddwrt-blacklist-domains

#!/bin/sh
#DEBUG=; set -x # comment/uncomment to disable/enable debug mode

#          name: ddwrt-blacklist-domains.sh
#       version: 3.1.0, 03-feb-2022, by eibgrad
#       purpose: blacklist specific domains in dnsmasq (dns)
#   script type: startup (autostart)
#  installation:
#    1. enable jffs2 (administration->jffs2)
#    2. enable syslogd (services->services->system log)
#    3. use shell (telnet/ssh) to execute one of the following commands:
#         curl -kLs bit.ly/ddwrt-installer|tr -d '\r'|sh -s aySi7RhY startup
#       or
#         wget -qO - bit.ly/ddwrt-installer|tr -d '\r'|sh -s aySi7RhY startup
#    4. add the following to the "additional dnsmasq options" field on the
#           services page:
#         addn-hosts=/tmp/blacklisted_domains
#    5. (optional) modify options using vi editor:
#         vi /jffs/etc/config/ddwrt-blacklist-domains.startup
#    6. (optional) enable cron (administration->management) and add the
#           following job:
#         0 4 * * * root /jffs/etc/config/ddwrt-blacklist-domains.startup
#    7. reboot
(
# ------------------------------ BEGIN OPTIONS ------------------------------- #

# websites known to maintain a list of blacklisted domains
# note: exercise caution when using commented urls; these sites often
#       contain *very* large lists of blacklisted domains, which may exceed
#       the memory capacity of the router and/or dnsmasq, and *may* have a
#       detrimental affect on dns performance
URL_LIST='
# minimal advertisers list - 6500 lines
https://raw.githubusercontent.com/Kees1958/W3C_annual_most_used_survey_blocklist/b551821c5c7a37aff96f999fae50f28f53ecf824/EU_US_MV2_most_common_ad%2Btracking_networks
# https://pgl.yoyo.org/adservers/serverlist.php?hostformat=&showintro=1&mimetype=plaintext # Peter Lowe 7300 lines
# https://raw.githubusercontent.com/hagezi/dns-blocklists/main/hosts/light.txt # hagezi light 
# https://raw.githubusercontent.com/lewisje/jansal/master/adblock/hosts # hosts 949 lines 
# https://raw.githubusercontent.com/lewisje/jansal/master/adblock/hostsc # hostsc 362 lines
'

# exceptions: domains (and their sub-domains) NOT to be blacklisted
# note: matching only occurs on whole parts of the domain name, moving right
#       to left; for example, adding somedomain.com to the whitelist would
#       also match xyz.somedomain.com, but NOT match xyzsomedomain.com nor
#       xyz.somedomain.com.us; wildcards (*) are NOT supported and will be
#       removed
WHITELIST='
localhost
'

# maximum time (in secs) alloted to any curl/wget operation
MAX_WAIT=60

# ------------------------------- END OPTIONS -------------------------------- #

# ---------------------- DO NOT CHANGE BELOW THIS LINE ----------------------- #

# required for serialization when reentry is possible
LOCK="/tmp/$(basename $0).lock"
acquire_lock() { while ! mkdir $LOCK >/dev/null 2>&1; do sleep 10; done; }
release_lock() { rmdir $LOCK >/dev/null 2>&1; }

# default to curl, failover to wget (not guaranteed to support tls)
which curl &>/dev/null && \
    GET_URL="curl -sLk --connect-timeout $MAX_WAIT --max-time $MAX_WAIT" || \
    GET_URL="wget -T $MAX_WAIT -qO -"

# domains to be blacklisted
BLACKLIST='/tmp/blacklisted_domains'; > $BLACKLIST

# workfile
RAW_BLACKLIST="/tmp/tmp.$$.raw_blacklist"

# wait for wan availability
until ping -qc1 -W3 8.8.8.8 &>/dev/null; do sleep 10; done

# one instance at a time
acquire_lock

# catch premature exit and cleanup
trap 'release_lock; exit 1' SIGHUP SIGINT SIGTERM

for url in $URL_LIST; do
    # skip comments and blank lines
    echo $url | grep -Eq '^[[:space:]]*(#|$)' && continue

    # retrieve url as raw blacklist
    $GET_URL $url > $RAW_BLACKLIST || { echo "error: $url"; continue; }

    # reformat as '0.0.0.0 domain-name' pairs
    awk '/^0\.0\.0\.0|^127\.0\.0\.1/{print "0.0.0.0 " $2}' $RAW_BLACKLIST | \
        # remove malformed domain names
        grep -E '^0\.0\.0\.0 [0-9A-z\.-]+$' >> $BLACKLIST
done

# cleanup
rm -f $RAW_BLACKLIST

# sort and remove duplicates
sort -uo $BLACKLIST $BLACKLIST

# remove domains and sub-domains that match whitelist
if [ "$(echo $WHITELIST)" ]; then
    sed -ri "/$(echo $WHITELIST | \
        sed -r 's/\*//g;s/( |$)/$|/g;s/\|$//;s/\./\\./g;s/([^|]*)/[ .]\1/g')/d" \
            $BLACKLIST
fi

# wait for dnsmasq availability
until pidof dnsmasq &>/dev/null; do sleep 10; done

# force dnsmasq to recognize updated blacklist
killall -HUP dnsmasq

# report the results
echo "info: total blacklisted domains: $(wc -l < $BLACKLIST)"

# any concurrent instance(s) may now run
release_lock

exit 0

) 2>&1 | logger $([ ${DEBUG+x} ] && echo '-p user.debug') \
    -t $(echo $(basename $0) | grep -Eo '^.{0,23}')[$$] &