2 :80

# use big.txt, quickhits.txt
$ ffuf -ic -w /usr/share/seclists/Discovery/Web-Content/* -u "http://silo.htb/FUZZ"
aspnet_client           [Status: 301, Size: 153, Words: 9, Lines: 2]
/Trace.axd              [Status: 403, Size: 2452, Words: 554, Lines: 58]

# not a ASP.NET server, thats why error.
http://silo.htb/trace.axd
Server Error in '/' Application.
Trace Error
Description: The current trace settings prevent trace.axd from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.
Details: To enable trace.axd to be viewable on remote machines, please create a <trace> tag within the configuration file located in the root directory of the current web application. This <trace> tag should then have its "localOnly" attribute set to "false".
<configuration>
    <system.web>
        <trace localOnly="false"/>
    </system.web>
</configuration>