From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id 04FE260A55 for ; Wed, 18 Nov 2020 08:44:08 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id EF6FF1802E for ; Wed, 18 Nov 2020 08:44:07 +0100 (CET) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [212.186.127.180]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id 4052418024 for ; Wed, 18 Nov 2020 08:44:07 +0100 (CET) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 043A5437E8 for ; Wed, 18 Nov 2020 08:44:07 +0100 (CET) To: Dietmar Maurer , Dominik Csapak , pmg-devel@lists.proxmox.com References: <20201117145743.10561-1-d.csapak@proxmox.com> <925752189.205.1605630434708@webmail.proxmox.com> <536187425.206.1605631117830@webmail.proxmox.com> From: Thomas Lamprecht Message-ID: Date: Wed, 18 Nov 2020 08:44:05 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:83.0) Gecko/20100101 Thunderbird/83.0 MIME-Version: 1.0 In-Reply-To: <536187425.206.1605631117830@webmail.proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-SPAM-LEVEL: Spam detection results: 0 AWL -0.087 Adjusted score from AWL reputation of From: address KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment NICE_REPLY_A -0.001 Looks like a legit reply (A) RCVD_IN_DNSWL_MED -2.3 Sender listed at https://www.dnswl.org/, medium trust SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record URIBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [wikipedia.org] Subject: Re: [pmg-devel] [PATCH pmg-api/gui] add quarantine self service button X-BeenThere: pmg-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Mail Gateway development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 18 Nov 2020 07:44:08 -0000 On 17.11.20 17:38, Dietmar Maurer wrote: >=20 >> On 11/17/2020 5:27 PM Dietmar Maurer wrote: >> >> =20 >> IMHO this is too dangerous. >> >> This needs at least some kind of captcha ... >=20 > i.e. This would allow direct DOS attacks to the internal mail server. >=20 I found this captcha solution, relatively sophisticated but not a PITA fo= r the (human) user, Friendly Captcha[0] used by some official European Union we= bsites. It uses Proof of Work[2] (i.e. crypto puzzel ones device needs to solve b= y computation), the specific library used is "Friendly PoW"[1]. If we go for a captcha I'd like something like this (could be rebuild), a= s it avoids the issues with picture texts (easily solved by computers, bad accessibility for humans) and similar captchas. [0]: https://github.com/friendlycaptcha/friendly-challenge [1]: https://github.com/friendlycaptcha/friendly-pow [2]: https://de.wikipedia.org/wiki/Proof_of_Work