Strange commands frequently received

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takfuji
500 Command not understood
Posts: 3
Joined: 2006-11-29 05:01
Location: Japan

Strange commands frequently received

#1 Post by takfuji » 2021-04-05 23:14

Could some guru teach me on this strange commands, which I receive frequently for recent months.
I would like to know whether this is a sort of attack, or just a behavior of a browser.

The log of Filezilla server is this:
> Connected on port 21, sending welcome message...
> 220 Welcome to the Tak's FTP service. Connection successful.
> ...
> 500 Syntax error, command unrecognized.
> ュ.
> 500 Syntax error, command unrecognized.
>
> disconnected.

The first command is substituted but it is actually Hex 16 03 03 0D 0A, and the second one is EF BD AD 01 0D 0A.
Thanks in advance
Tak
Tak

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botg
Site Admin
Posts: 33425
Joined: 2004-02-23 20:49
First name: Tim
Last name: Kosse
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Re: Strange commands frequently received

#2 Post by botg » 2021-04-06 08:16

16 03 03, looks like a TLS handshake record. Most likely from some automated scanners.

Safe to ignore, doesn't harm FileZilla Server. If it bothers you, block the offending IP addresses, possibly already in your firewall.

takfuji
500 Command not understood
Posts: 3
Joined: 2006-11-29 05:01
Location: Japan

Re: Strange commands frequently received

#3 Post by takfuji » 2021-04-06 12:23

Thank you,
I will just ignore them as recommended.
Tak
Tak

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