Ping many DNS servers (in batches) and print sorted table of results

dns-test

#!/usr/bin/env bash
# Russell Harkanson - 2019
# dns-test
# Ping many DNS servers (in batches) and print sorted table of results
#
# usage: ./dns-test [C] [S] [N]
#     C - ping count for each DNS (5)
#     S - sort column 1:Name 2:IP 3:Loss 4:Min 5:Avg 6:Max 7:StDev (5)
#     N - parallel operations at once (4)


# Kindly provided by https://twitgoo.com/best-free-dns-servers/
# Remove or add DNS to list with form <name>/<ip>
DNS_ADDRS=(Google/8.8.8.8
OpenDNSHome/208.67.222.222
CloudFlare/1.1.1.1
Quad9/9.9.9.9
Level3/209.244.0.3
Verisign/64.6.64.6
DNS.WATCH/84.200.69.80
ComodoSecureDNS/8.26.56.26
GreenTeamDNS/81.218.119.11
SafeDNS/195.46.39.39
OpenNIC/23.94.60.240
SmartViper/208.76.50.50
Dyn/216.146.35.35
FreeDNS/37.235.1.174
AlternateDNS/198.101.242.72
Yandex.DNS/77.88.8.8
UncensoredDNS/91.239.100.100
HurricaneElectric/74.82.42.42
puntCAT/109.69.8.51)


# Number of pings (default 5)
C=${1:-5}

# Sort column (default 5 - Avg)
##    1    2  3    4   5   6   7
COLS=(Name IP Loss Min Avg Max StDev)
S=${2:-5}

# Parallel procs (default 4)
N=${3:-4}

# Indicate sort column
S_num=$(cut -d',' -f 1 <<< "$S")
COLS[$S_num-1]="[${COLS[$S_num-1]}]"
COLS_HDR="$( printf "%s, \t%s, \t%s, \t%s, \t%s, \t%s, \t%s" ${COLS[*]} )"

# Run in batches of N, report results
(
for dns in "${DNS_ADDRS[@]}"; do
  dnsip=$(cut -d'/' -f 2 <<< "$dns")
  ((i=i%N)); ((i++==0)) && wait
  ping -q -c $C $dnsip | awk 'match($0, / ([0-9\.]+)%/) {loss=substr( $0, RSTART, RLENGTH-1)} $3=="="{stats=$4} END{if(int(loss)==100) print "'"$dns"'/"loss"%/--/--/--/--"; else print "'"$dns"'/"loss"%/"stats}'  & 
done
) | sort -V -t '/' -k $S | awk -v FS='/' 'BEGIN{print "'"$COLS_HDR"'"} {r=""; for(i=1;i<7;i++) r=r""$(i)", \t"; print r""$7}' | column -t