Defense against nmap tcp synchronise scans

Jul 23, 2013 2 Replies

Assuming that a host does not require a Telnet service running in it, is it possible to create a fake telenet process that listens to the Telnet port and blocks all IP that tries to make a connection (TCP-SYN) with it ?? The attacker when tries to scan this host using nmap, it makes send a TCP-SYN t o telnet port (not in all cases) , the host can now get the source IP and b locks all connection from that IP. Will this defense concept work ???


iptables -A -p tcp --dport 23 -j REJECT is one solution.

Doesn't make sense at all and is no defense concept.

cheers

Google for portsentry. It's an ancient script/tool that does this.

Best regards Thomas

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