Check the number of connections using nf_conntrack or using tcpdump

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tcpdump -tnn -ieth0 -c 20000 | awk -F ">" '{print $1}' | awk -F " " '{print $2}' | awk -F "." '{print $1"."$2"."$3"."$4}' | sort | uniq -c | sort -nr | awk ' $1 > 100 '

Note : If the network interface card in use on the server is eth0

cat /proc/net/nf_conntrack > contoutput && cat contoutput | awk '{ print $7,$8 }' | sort | uniq -c | sort -rn | head

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