2020年3月8日 · Filtered is described in the NMAP Reference Guide, Chapter 15: Nmap cannot determine whether the port is open because packet filtering prevents its probes from reaching the port. The filtering could be from a dedicated firewall device, router rules, or host-based firewall software. These ports frustrate attackers because they provide so little information. Sometimes they respond with ICMP ...

This forces Nmap to retry several times just in case the probe was dropped due to network congestion rather than filtering. This sort of filtering slows scans down dramatically. open|filtered : Nmap places ports in this state when it is unable to determine whether a port is open or filtered.

2018年3月29日 · This largely depends on the used scan. The Nmap scan types page explains the status of the port and the reasons per scan. Some examples: TCP SYN Scan (-sS) - Sends a TCP packet with SYN flag set - If a SYN/ACK (or SYN) is received --> Port is Open, TCP initiation accepted - If a RST is received --> Port is closed - If no response is received --> Port is considered filtered - If a ICMP ...

2019年2月1日 · Nmap port scan output shows (at least) 2 different things for each port: the state of the port, and the reason why Nmap decided on that state. In your output, all the ports in the filtered state are being presented together, with counts for each of the two reasons it decided on that state for each port.

2016年12月19日 · Nmap draws a negative inference here and assumes access to the port is being filtered by a firewall. And that's why you see closed on one system and filtered on the other. In the first case, the host or firewall is returning RST in order to block unwanted packets, which gives nmap an unequivocal signal that the port is closed.

2020年9月12日 · If nmap shows all ports are filtered or closed, what would be the next logical step to take? Does that mean I would need to get physical access to the device? or is there any other ways to get information?

2014年7月4日 · When nmap scans a TCP port (e.g. TCP/80 for HTTP traffic) a filtered response means that nmap did not get any response to the packet it sent. The other options for TCP ports are "closed" which means that in response to the SYN packet nmap sent, the host sent a RST packet (essentially indicating that there is no service listening on that port) or "open" which means that nmap got an ACK packet ...

2022年12月8日 · Is there a way to identify whether "filtered" state for a specific port in nmap output is caused by a network firewall or host-based firewall?

2018年1月22日 · The nmap manual states (emphasis mine): The state is either open, filtered, closed, or unfiltered. Open means that an application on the target machine is listening for connections/packets on that port. Filtered means that a firewall, filter, or other network obstacle is blocking the port so that Nmap cannot tell whether it is open or closed.

2011年11月30日 · I'm performing an port scanning on a range of IPs on our remote site. I tried running nmap scan on that IP range and some of the IP result are shown as filtered When I perform a nessus scan on the...