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260 lines
10 KiB
Markdown
260 lines
10 KiB
Markdown
# Suricata & Iptables cheatsheet
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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## Iptables
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### Chains
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In iptables, lists of rules known as chains are processed sequentially. Among these, three primary chains are universally present, with additional ones like NAT being potentially supported depending on the system's capabilities.
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- **Input Chain**: Utilized for managing the behavior of incoming connections.
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- **Forward Chain**: Employed for handling incoming connections that are not destined for the local system. This is typical for devices acting as routers, where the data received is meant to be forwarded to another destination. This chain is relevant primarily when the system is involved in routing, NATing, or similar activities.
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- **Output Chain**: Dedicated to the regulation of outgoing connections.
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These chains ensure the orderly processing of network traffic, allowing for the specification of detailed rules governing the flow of data into, through, and out of a system.
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```bash
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# Delete all rules
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iptables -F
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# List all rules
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iptables -L
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iptables -S
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# Block IP addresses & ports
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iptables -I INPUT -s ip1,ip2,ip3 -j DROP
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iptables -I INPUT -p tcp --dport 443 -j DROP
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iptables -I INPUT -s ip1,ip2 -p tcp --dport 443 -j DROP
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# String based drop
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## Strings are case sensitive (pretty easy to bypass if you want to check an SQLi for example)
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iptables -I INPUT -p tcp --dport <port_listening> -m string --algo bm --string '<payload>' -j DROP
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iptables -I OUTPUT -p tcp --sport <port_listening> -m string --algo bm --string 'CTF{' -j DROP
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## You can also check for the hex, base64 and double base64 of the expected CTF flag chars
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# Drop every input port except some
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iptables -P INPUT DROP # Default to drop
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iptables -I INPUT -p tcp --dport 8000 -j ACCEPT
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iptables -I INPUT -p tcp --dport 443 -j ACCEPT
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# Persist Iptables
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## Debian/Ubuntu:
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apt-get install iptables-persistent
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iptables-save > /etc/iptables/rules.v4
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ip6tables-save > /etc/iptables/rules.v6
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iptables-restore < /etc/iptables/rules.v4
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##RHEL/CentOS:
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iptables-save > /etc/sysconfig/iptables
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ip6tables-save > /etc/sysconfig/ip6tables
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iptables-restore < /etc/sysconfig/iptables
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```
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## Suricata
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### Install & Config
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```bash
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# Install details from: https://suricata.readthedocs.io/en/suricata-6.0.0/install.html#install-binary-packages
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# Ubuntu
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add-apt-repository ppa:oisf/suricata-stable
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apt-get update
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apt-get install suricata
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# Debian
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echo "deb http://http.debian.net/debian buster-backports main" > \
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/etc/apt/sources.list.d/backports.list
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apt-get update
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apt-get install suricata -t buster-backports
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# CentOS
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yum install epel-release
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yum install suricata
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# Get rules
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suricata-update
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suricata-update list-sources #List sources of the rules
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suricata-update enable-source et/open #Add et/open rulesets
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suricata-update
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## To use the dowloaded rules update the following line in /etc/suricata/suricata.yaml
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default-rule-path: /var/lib/suricata/rules
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rule-files:
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- suricata.rules
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# Run
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## Add rules in /etc/suricata/rules/suricata.rules
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systemctl suricata start
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suricata -c /etc/suricata/suricata.yaml -i eth0
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# Reload rules
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suricatasc -c ruleset-reload-nonblocking
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## or set the follogin in /etc/suricata/suricata.yaml
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detect-engine:
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- rule-reload: true
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# Validate suricata config
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suricata -T -c /etc/suricata/suricata.yaml -v
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# Configure suricata as IPs
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## Config drop to generate alerts
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## Search for the following lines in /etc/suricata/suricata.yaml and remove comments:
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- drop:
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alerts: yes
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flows: all
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## Forward all packages to the queue where suricata can act as IPS
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iptables -I INPUT -j NFQUEUE
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iptables -I OUTPUT -j NFQUEUE
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## Start suricata in IPS mode
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suricata -c /etc/suricata/suricata.yaml -q 0
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### or modify the service config file as:
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systemctl edit suricata.service
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[Service]
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ExecStart=
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ExecStart=/usr/bin/suricata -c /etc/suricata/suricata.yaml --pidfile /run/suricata.pid -q 0 -vvv
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Type=simple
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systemctl daemon-reload
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```
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### Rules Definitions
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[From the docs:](https://github.com/OISF/suricata/blob/master/doc/userguide/rules/intro.rst) A rule/signature consists of the following:
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* The **action**, determines what happens when the signature matches.
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* The **header**, defines the protocol, IP addresses, ports and direction of the rule.
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* The **rule options**, define the specifics of the rule.
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```bash
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alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"HTTP GET Request Containing Rule in URI"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"rule"; fast_pattern; classtype:bad-unknown; sid:123; rev:1;)
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```
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#### **Valid actions are**
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* alert - generate an alert
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* pass - stop further inspection of the packet
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* **drop** - drop packet and generate alert
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* **reject** - send RST/ICMP unreachable error to the sender of the matching packet.
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* rejectsrc - same as just _reject_
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* rejectdst - send RST/ICMP error packet to the receiver of the matching packet.
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* rejectboth - send RST/ICMP error packets to both sides of the conversation.
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#### **Protocols**
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* tcp (for tcp-traffic)
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* udp
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* icmp
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* ip (ip stands for ‘all’ or ‘any’)
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* _layer7 protocols_: http, ftp, tls, smb, dns, ssh... (more in the [**docs**](https://suricata.readthedocs.io/en/suricata-6.0.0/rules/intro.html))
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#### Source and Destination Addresses
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It supports IP ranges, negations and a list of addresses:
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| Example | Meaning |
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| ------------------------------ | ---------------------------------------- |
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| ! 1.1.1.1 | Every IP address but 1.1.1.1 |
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| !\[1.1.1.1, 1.1.1.2] | Every IP address but 1.1.1.1 and 1.1.1.2 |
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| $HOME\_NET | Your setting of HOME\_NET in yaml |
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| \[$EXTERNAL\_NET, !$HOME\_NET] | EXTERNAL\_NET and not HOME\_NET |
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| \[10.0.0.0/24, !10.0.0.5] | 10.0.0.0/24 except for 10.0.0.5 |
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#### Source and Destination Ports
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It supports port ranges, negations and lists of ports
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| Example | Meaning |
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| --------------- | -------------------------------------- |
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| any | any address |
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| \[80, 81, 82] | port 80, 81 and 82 |
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| \[80: 82] | Range from 80 till 82 |
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| \[1024: ] | From 1024 till the highest port-number |
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| !80 | Every port but 80 |
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| \[80:100,!99] | Range from 80 till 100 but 99 excluded |
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| \[1:80,!\[2,4]] | Range from 1-80, except ports 2 and 4 |
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#### Direction
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It's possible to indicate the direction of the communication rule being applied:
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```
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source -> destination
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source <> destination (both directions)
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```
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#### Keywords
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There are **hundreds of options** available in Suricata to search for the **specific packet** you are looking for, here it will be mentioned if something interesting is found. Check the [**documentation** ](https://suricata.readthedocs.io/en/suricata-6.0.0/rules/index.html)for more!
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```bash
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# Meta Keywords
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msg: "description"; #Set a description to the rule
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sid:123 #Set a unique ID to the rule
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rev:1 #Rule revision number
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config classification: not-suspicious,Not Suspicious Traffic,3 #Classify
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reference: url, www.info.com #Reference
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priority:1; #Set a priority
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metadata: key value, key value; #Extra metadata
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# Filter by geolocation
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geoip: src,RU;
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# ICMP type & Code
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itype:<10;
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icode:0
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# Filter by string
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content: "something"
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content: |61 61 61| #Hex: AAA
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content: "http|3A|//" #Mix string and hex
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content: "abc"; nocase; #Case insensitive
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reject tcp any any -> any any (msg: "php-rce"; content: "eval"; nocase; metadata: tag php-rce; sid:101; rev: 1;)
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# Replaces string
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## Content and replace string must have the same length
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content:"abc"; replace: "def"
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alert tcp any any -> any any (msg: "flag replace"; content: "CTF{a6st"; replace: "CTF{u798"; nocase; sid:100; rev: 1;)
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## The replace works in both input and output packets
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## But it only modifies the first match
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# Filter by regex
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pcre:"/<regex>/opts"
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pcre:"/NICK .*USA.*[0-9]{3,}/i"
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drop tcp any any -> any any (msg:"regex"; pcre:"/CTF\{[\w]{3}/i"; sid:10001;)
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# Other examples
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## Drop by port
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drop tcp any any -> any 8000 (msg:"8000 port"; sid:1000;)
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```
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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||
<details>
|
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|
||
<summary>Support HackTricks</summary>
|
||
|
||
* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
|
||
* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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