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Questions tagged [snort]

Snort is an open source network intrusion detection and prevention system (NIDS/NIPS).

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OpenAppID with Snort on pfSense

I'm using OpenAppID with Snort on pfSense, it actually work but when I view some script detector, it just detect by http pattern, which I can replace by using snort rule (with "content" option). So ...
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How to run a snort rule over PCAP file in Windows? [duplicate]

I have a PCAP file from CICIDS, and what I'd like to know is how can I apply the Snortrule in Windows? I've not written any custom rules myself but want to run the rules already available. For now, ...
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Snort rule for syn flood attacks - Limiting number of alerts

So I have a snort rule that detects syn flood attacks that looks like this: alert tcp any any -> $HOME_NET 80 (msg:”SYN Flood - SSH"; flags:S; flow: stateless; detection_filter: track by_dst, ...
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2answers
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How to analyze .pcap file to write a generic snort rule to detect c&c activity

I am diving into snort and trying to figure out what everything does but I'm having a little trouble. I have a .pcap file I want to analyse and I know there is malicious c&c traffic on it. (...
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1answer
49 views

Is there a way to change the format of the output from snort?

I'm pretty new to snort and don't know too much about it. I am trying to put together a report of my snort files but, I only want the connections not the entire flows. For example, say I have a few ...
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Can an IDS be used for detecting frames (not packets) from an non-authenticated station

Can an IDS, like snort, be used to detect Layer 2 network frames from a system i.e a system is trying to send a frame to the AP and whether Snort can work on the frame based on the rules?
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201 views

Create a snort rule that will alert on traffic on ports 443 & 447

Using the Immersivelabs learning platform, the subject is snort rules. Question is: Create a snort rule that will alert on traffic with destination ports 443 and 447. My attempts: alert tcp ...
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55 views

How to determine TLS traffic in snort signature

I am trying to have a snort signature that can detect encrypted traffic but I am not able to determine the TLS traffic using a snort signature. The content keyword search in the payload of the packet,...
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1answer
80 views

Are these snort alerts false positives or attacks?

Can anyone describe this alert please? I am confused if an attack is run against my network or not. I run snort IDS/IPS through a pfsense firewall.
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In Snort for Windows, how do I limit log file size, keep that file, and make another file instance

I have Snort for Windows. I am trying to make a log file of say size limit 1MB. When the log file hits the 1MB maximum, I want it to close that file (snort.log.1234567890) and open a new log file ...
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Snort CSV details @ alert

I have enabled the fast logging mode, my question here is how can I extract the CVE details or reference tag inside the /var/log/alert file, as if now I am able to see only this much data in alert ...
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Threshold for DDOS Attack

I am trying to understand and simulate SYN Flood DDOS attacks. I am using snort to give me alerts. While I have control over the rate for my testing, I am interested in knowing what a good estimate of ...
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1answer
252 views

How to sniff VPN traffic using Snort?

Here's what I want to do: I want to use a VPN client on my PC (like TunnelBear). Then I want to use Snort to sniff traffic before it's encrypted and after it's decrypted by VPN. So basically I want ...
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1answer
149 views

Loopback with Suricata

Is there any way of analyzing loopback traffic with Suricata? I am trying it this way without success: root@security-onion:/home/sar/TFM/alerts/suricata# suricata -c /etc/suricata/suricata.yaml -i ...
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174 views

Analyzing Apache log with Snort

I need to analyze an Apache log with Snort and others IDS/WAFs (Suricata, mod_security and Shadow Daemon). In order to do so, I was thinking about create TCP packets with the GET and POST requests ...
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Are these Snort rules correct?

I wrote this rule so that when there are more than three failed SSH connection attempts that there is an alert but it is not working. Are these rules badly written? Or if not I ask the exact writing ...
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158 views

snort rules are enabled by pulledpork but in the same time are skipped?

I am using pulledpork for management of rules. I had enabled rules from 1:1000 to 1:5735 those rules are enabled but in the same time are skipped. As output I had: https://github.com/shirkdog/...
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Snort not working with IDSWakeup

I have setup Snort with the registered user rules installed. I tested first by making the following rule in local.rules: alert icmp any any -> $HOME_NET any (msg:"ICMP test"; sid:10000001; rev:...
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207 views

How can I get Suricata to alert on 1 packet every time

I am trying to write a Suricata signature for testing purposes to alert every time it is triggered with a single PCAP file containing a single packet, but this is proving to be harder than I thought. ...
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0 dynamic rules read

I am running Snort as IDS in Security Onion and get this message: 0 Dynamic rules All SO_RULES are loaded in snort.conf in the correct path. 25867 Snort rules read 23950 detection rules ...
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4answers
939 views

Benefit of using two network interfaces for intrusion detection system

What is the benefit of using two network interfaces (management interface and sniffing interface) for an IDS such as Snort? I have used a Snort IDS where it only used one network interface for both ...
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2answers
290 views

how to write a snort rule to alert traffic that does not find any matched rules

Snort in IDS mode: If there is some traffic that does NOT find any matched rule against all existing Snort rules, how would you write a bottom rule to alert this traffic?
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1answer
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pcap files for simulated attacks on SCADA systems?

I need to get hold of some pcap files belonging to a simulated attack on SCADA systems. My goal is to then use Snort for the detection. Or if somebody can suggest a practical environment to create my ...
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0answers
360 views

Snort.log output as unreadable symbols

I have recently installed Snort IDS on Linux Ubuntu 16.04LTS (not server), after experimenting and testing configuration in VitualBox. After installing and successfully validating the configuration ...
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1answer
189 views

How do I map the information in snort u2spewfoo output to the rule which triggered the alert?

I have a snort log file in unified2 format and I am able to view the output using the u2spewfoo utility. I think that I understand the generator id, signature id, and revision tell me why the alert ...
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2answers
557 views

Snort Exercises

I am beginning to study Snort rules and the teacher give to us the next exercises: A server on which Snort is installed is monitoring all traffic on subnet 172.16.0.0 with mask 255.255.0.0. From now ...
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snort add more data in alert file

I want to add more data to alert file rightnow the data what our analyst team see is very minimal and we are not giving access to them to our snort backend server, our design is like centos /var/log/...
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1answer
2k views

Snort priority range

What is the range of values for the 'priority' parameter in a Snort rule? The documentation it doesn't make it clear: The priority tag assigns a severity level to rules. A classtype rule assigns a ...
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1answer
295 views

Security Onion VMWare + OpenWRT IPTables Mirroring

I'm trying to set up SO in my home network to lab and see if I can monitor all ingress/egress traffic from my SOHO router. I don't have a switch with SPAN ports, or a network tap so I'm using OpenWRT ...
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1answer
728 views

How to detect a string in HTML with Snort?

I am trying to detect a string in HTML (already unzipped) with Snort. I set this rule to find content 7038685658 in my Apache web server's HTML: alert tcp any any <> any any (msg:"cell"; ...
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1answer
1k views

IDS Snort rule to catch Slow-Loris

I'm trying to write a rule to catch a Slow-Loris attack, this is what i have - alert tcp any any -> any any (msg:"Possible Slow Loris attack"; classtype: denial-of-service; flow: to_server, ...
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1answer
279 views

Suricata does not detect “self” traffic

I have built two simple rules alert tcp any any -> any any (msg: "tcp detected"; sid: 2; rev: 1;) alert udp any any -> any any (msg: "udp detected"; sid: 1; rev: 1;) Then from the same machine ...
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2answers
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Can dual NIC Snort machine cause threats to bypass firewall?

I am thinking about building a Linux Snort machine that can listen to both WAN and LAN traffic. Setup I am thinking about: Snort computer with two NICs One NIC connected to hub/tap outside firewall (...
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snort file_inspect signature working inconsistently [closed]

I am trying snorts file inspect preprocessor for blocking incoming files from their sha256sums. I am using snort version 2.9.9.0 with daq nfq inline mode any my file_inspect preprocessor configs are ...
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1answer
327 views

Snort: Cannot decode data link type 127 reading a pcapng file

I've captured on my wifi some days ago and now I want snort to analyse the capture to detect any problem. However, when I run snort -l ./snort-log -b -c /etc/snort/snort.conf -r captura-analisar....
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2answers
165 views

How to detect long lived SSH sessioned

I am trying to figure out a way to detect ssh sessions that have been established over a long period of time. I seem to recall that there were ways to detect tcp connections that have been connected ...
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2answers
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Major differences between Snort and Snort 3.0

When I visited the the Snort's website to download the source code for compilation, I found there were 2 downloads available. One was titled Snort and another was titled Snort 3.0 Has the ...
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2answers
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REJECT Nikto Scans With Snort Rules

Hoping someone on here knows a way to reject Nikto traffic with Snort rules. I've been having zero luck for days finding this anywhere online. Thanks. Peace.
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how to use snort to track http/https sessions separately?

how can I use snort to breakdown http/https traffic into separate sessions and track each session separately and also dump them into separate log files or something that I can read from.
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3answers
9k views

Can Snort run on a Raspberry Pi?

I am in the preliminary stages of designing a cybersecurity suite for my home network. I don't have any servers or anything, just the standard home setup (computers, tablets, game consoles). The ...
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1answer
280 views

Can I run Snort on a slow computer?

I'm trying to use a device with 1GB of RAM and a Single 800 MHz core CPU. I will use Snort to analyze traffic on my LAN network. Snort, unfortunately, cannot analyze all the traffic (sometimes it ...
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Signature Generate by Honeyd “Honeycomb” is not accept by Snort IPS

I posted this on SO [https://stackoverflow.com/questions/44652014/signature-generate-by-honeyd-honeycomb-is-not-accept-by-snort-ips] is this on topic here? What would I need to do to my question ? I ...
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1answer
465 views

Snort Alert - What is PROTO:255?

My Snort alert output is like below. The first element of 4th row of each alert indicates Protocol. However, in the alert (portscan) TCP Portscan, the protocol is PROTO:255. What does it mean? Why ...
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0answers
273 views

Detecting Guest to Guest Traffic in Virtualbox Using Host Running Snort

Not sure if this is a simple question but I was hoping for some insight into finishing a pentest lab. My goal is to have Snort sniff an attack in a virtual environment between two guest VM's. My ...
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204 views

How to log only the TCP header using command line in snort or nmap? [closed]

I work with snort log file and now I need to extract the TCP header. My question is: How to log only the TCP header from the packets captured by snort log file (without the payload) using command ...
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How does the flow option of Snort work?

For example, flow:established is detecting only for packets with sessions connected. Then, the server is rejecting packets to received after the session is disconnected?
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1answer
584 views

Troubleshooting Snort Rules

I am trying to troubleshoot a bunch of flowbits generated by pulledpork from snortrules-snapshot-2990.tar.gz. WARNING: flowbits key 'file.pdf' is set but not ever checked. The line in the generated ...
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0answers
232 views

Snort generates an alert that is empty [closed]

I am working with commands that have already been tested to work but they aren't working now. This is my config file: alert tcp any any <> any any (msg: "/etc/passwd Payload Found"; content: "/...
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1answer
282 views

How to inspect TCP Header -> Optional Data with Snort?

I have been looking around for clues on how to define rules, decoders or preprocessors to be able to content-inspect the TCP Header's Optional Data ( The last 0-40 bytes of the TCP Header) TCP ...
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1answer
446 views

Where can I find a snort signature for detecting slowhttp DoS attack from Slowloris tool [duplicate]

I am performing a test on some DoS attacks and how to detect them. I am currently testing the slowloris tool, but all the signature I have seen online, as very very few as they are,do not work even ...