# Firewall and IDS/IPS Evasion To determine firewall rules the `-sA` scan is very useful Detecting the presence of IDS or IPS systems may get your IP blocked. It's useful to have multiple VPS boxes with different IPs to perform the pentesting from. ### Decoys Flag: `-D` Generates random IP addresses (for example 5: `-D RND:5`) and uses them as sender addresses in the TCP headers **in addition to our own** actual address. For good measure and to not get detected as a SYN Flood the IP addresses used should be alive. It's possible to manually specify the source IP address with: `-S` usually with `-e tun0` to specify the interface Decoys can be used for SYN, ACK, ICMP scans, and OS detection scans ### DNS Proxying DNS usually uses port `53/UDP` but some modern specifications also use `53/TCP` (Zone transfer, DNSSEC). For this, we can use port 53 as our own source port to be more highly trusted by some not perfectly setup IDS/IPS `--source-port 53` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.rtlcopymemory.com/enumeration/firewall-and-ids-ips-evasion.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.