network_security_assesment
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| Media video stream and PowerPoint presentation from [[ http://www.blackhat.com/html/bh-usa-00/bh-usa-00-speakers.html | Link]] | Media video stream and PowerPoint presentation from [[ http://www.blackhat.com/html/bh-usa-00/bh-usa-00-speakers.html | Link]] | ||
| - | [[91]] | + | === Low-Level IP Assessment === |
| + | Tools such as Nmap, Hping2, and Firewalk perform low-level IP assessment. | ||
| + | |||
| + | Insight into the following areas of a network can be gleaned through low-level IP assessment: | ||
| + | |||
| + | * Uptime of target hosts (by analyzing the TCP timestamp option) | ||
| + | * TCP services that are permitted through the firewall (by analyzing responses to TCP and ICMP probes) | ||
| + | * TCP sequence and IP ID incrementation (by running predictability tests) | ||
| + | * The operating system of the target host (using IP fingerprinting) | ||
| + | |||
| + | The TCP timestamp option is defined in RFC 1323. | ||
| + | == Analyzing Responses to TCP Probes == | ||
| + | A TCP probe always results in one of four responses. These responses potentially\\ | ||
| + | allow an analyst to identify where a connection was accepted, or why and where it\\ | ||
| + | was rejected, dropped, or lost: | ||
| + | * TCP SYN/ACK | ||
| + | If a SYN/ACK packet is received, the port is considered open. | ||
| + | * TCP RST/ACK | ||
| + | If an RST/ACK packet is received, the probe packet was rejected by either the\\ | ||
| + | target host or an upstream security device (e.g., a firewall with a reject rule in its policy). | ||
| + | * ICMP type 3 code 13 | ||
| + | If an ICMP type 3 code 13 message is received, the host (or a device such as a\\ | ||
| + | firewall) has administratively prohibited the connection according to an Access Control List (ACL) rule. | ||
| + | * Nothing | ||
| + | If no packet is received, an intermediary security device silently dropped it. | ||
| + | |||
| + | [[96]] | ||
network_security_assesment.txt · Last modified: 2020/08/10 02:35 (external edit)
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