FAQ — IVRE documentation

# FAQ

If you cannot find the answer to your question, either here or in this documentation, feel free to open an issue and use the label “question”.

## Web interface

### Notebook shows “Forbidden”

I cannot access the notepad (the Dokuwiki content), and get a “Forbidden” message.

You need to configure your web server to allow access from other hosts on the network to the Dokuwiki content. It is often restricted, by default, to local users only. If you are using Apache, you can look for an ACL like `Allow from localhost 127.0.0.1 ::1` and adapt it to your network.

### The Web interface shows no result

I have inserted scan results, yet when I open the Web interface, it remains empty.

Two problems can explain this situation:

- The results are stored in the scan collection, but no view has been created (the Web interface displays results from the view).

- The Web interface does not access the database for some reason.

First, from the command line, check that a view has been created by running `ivre view --count`. If it displays `0`, it means that while you have inserted results in the `scan` database, you have not updated the `view` (see Purposes). You can create a view by using the `ivre db2view` CLI tool.

If `ivre view --count` does not display `0` but a (positive!) number, it means that, for some reason, the CGI cannot access the database. It could be because you are using a user-specific configuration (in `~/.ivre.conf`) and the CGI application runs with a different user. To investigate the problem, you have to check the Web server error logs.

### How can I restrict access to IVRE’s Web interface

I want to prevent unauthorized access to IVRE’s results.

First, you have to configure your web server to authenticate remote users. The most important, of course, is to protect access to CGI files (the static files are publicly available and do not contain any result).

In an AD or Kerberos environment for example, Apache can be configured to provide SSO authentication.

Then, if you want to restrict access to the results based on the user login or domain, you can add the following lines to `/etc/ivre.conf`:

    WEB_DEFAULT_INIT_QUERY = 'noaccess'
    WEB_INIT_QUERIES = {
        'admin@SUBNETWORK.NETWORK.AD': 'category:SubNetwork',
        '@ADMIN.NETWORK.AD': 'full',
    }

By default, users won’t have access to any result. The user `admin@SUBNETWORK.NETWORK.AD` will have access to the results in the category `SubNetwork`. The users in the `ADMIN.NETWORK.AD` realm will have access to all the results.

## Scanning the Internet is slow!

This is based on issue GH#822.

When running `ivre runscans --routable --limit 40`, one can notice the scan really takes a long time to terminate.

First of all, IVRE is not guilty here. IVRE runs Nmap, feeds it with targets, and wait for its output. You would get the same results using the same Nmap options as IVRE.

That being said, we have several ways to speed up a scan.

### Use Masscan rather that Nmap

This is pretty radical, and have an important drawback: Masscan results gather less intelligence than Nmap (a lot less in some situations).

However, it is often the only option to get comprehensive scans of the IPv4 routable address space.

A trade-off could be, for some protocols, to use Zmap / Zgrab2. Compare the possibilities of Masscan (`--banner`) versus Zgrab2 for the protocol(s) you want to scan.

IVRE will happily combine results from Nmap, Masscan and Zgrab / Zgrab2: you can build your own, perfectly suited, scanning solution and use IVRE to merge and browse the results.

### Parallelize Nmap scans

Another option is to run several Nmap processes instead of one. Theoretically it should not work, since Nmap is supposed to handle efficiently the resources, but it has proven useful in several situations, particularly when scanning heavily filtered hosts or random hosts across the Internet.

For that, one can either use an agent (see Agents) or `ivre runscans --output XMLFork --processes <n>` where `<n>` is the number of simultaneous Nmap processes to use.

## Can IVRE be used to look for XXX?

IVRE is not a scanner or a network traffic analyzer. It relies on tools like Nmap, Masscan, ZGrab2, and Zeek, parses their results and stores them in a database.

So when you are asking, for example, “can IVRE scan a network for hosts with the Heartbleed vulnerability?”, in reality you are asking two different questions:

- “Can Nmap or Masscan or Zgrab2 detect when a scanned hosts is vulnerable to the Heartbleed vulnerability?”

- “How can IVRE list the hosts that have been found vulnerable to Heartbleed by Nmap or Masscan?”

The first question is not related to IVRE (and should probably be asked to Nmap, Masscan or Zgrab2 developers), but the second question is (and may be asked as a “question” labeled issue).

For that particular Heartbleed example, Nmap, Masscan and Zgrab2 can (reliably) report hosts with the Heartbleed vulnerability, and IVRE can be used to find such hosts.

## How can I configure iptables to get logs used by flow2db tool

When you don’t have access to low level network data, an easy way to discover a part of network traffic is to use netfilter logs collected via syslog.

To be efficient, all the systems must have iptables activated and configured to send logs.

For example

    -A INPUT   -j LOG --log-prefix "IPTABLES/INPUT: "
    -A OUTPUT  -j LOG --log-prefix "IPTABLES/OUTPUT: "
    -A FORWARD -j LOG --log-prefix "IPTABLES/FORWARD: "

To log all traffic, the rules can be set at the top of all rules. Be careful with the OUTPUT rule if the logs are sent over the network!

On the syslog server or on each host, just run grep to collect the data needed for the iptables flow2db parser:

    $ grep -l 'IPTABLES/' /var/log/syslog /var/log/kernel.log ... \
        > syslog-iptables.log

Then import data to ivredb using flow2db tool:

    $ ivre flow2db -t iptables syslog-iptables.log