In Linode siamo estremamente orgogliosi dei nostri team di Assistenza Clienti e di Fiducia e Sicurezza e del lavoro che svolgono insieme; sono team composti da persone reali che condividono un obiettivo importante: mantenere la nostra piattaforma sicura e libera da abusi e frodi e creare politiche che mantengano i nostri clienti al sicuro. Questo significa che quando inviate un'e-mail a abuse@linode.com, potete aspettarvi di sentire, di solito entro pochi minuti, una persona reale, un membro di un intero team che ha seguito una formazione approfondita per comprendere tutte le complessità che possono derivare dalla gestione degli abusi e che può rispondere alle segnalazioni con empatia e urgenza.
Uno dei problemi più comuni per i nostri team (e per il nostro settore) è l'abuso di e-mail di spam. Costituisce una parte significativa dei problemi che il nostro team Trust & Safety deve gestire, ed è un problema che diventa sempre più difficile da risolvere ogni anno, man mano che gli utenti fraudolenti si adattano ai nuovi metodi per fermare e bloccare gli abusi. Con la crescita di Linode, abbiamo riflettuto su ciò che possiamo fare per dissuadere gli spammer e gli utenti fraudolenti dall'utilizzare la nostra piattaforma.
In risposta a questo problema, a partire da oggi, i Linode sui nuovi account cliente creati avranno le connessioni in uscita dalle porte 25, 465 e 587 limitate per impostazione predefinita. Questa modifica riguarda solo i clienti che si iscrivono a partire da oggi; se siete già clienti Linode, non verranno apportate modifiche a nessun Linode esistente o nuovo.
La limitazione dell'accesso a queste porte, utilizzate per l'invio di posta elettronica tramite SMTP, contribuirà a ridurre la quantità di spam trasmessa dalla nostra piattaforma. Tuttavia, riconosciamo anche che molti clienti hanno una necessità legittima di inviare posta e vogliamo aiutarli a farlo. Per questi clienti, il processo di rimozione di queste restrizioni è semplice:
- Configurare record A e reverse DNS validi per i Linode che si desidera utilizzare per la posta.
- Aprite un ticket di assistenza e forniteci alcune informazioni di base (le informazioni che vi chiederemo sono descritte nella nostra guida "Gestione di un server di posta").
Il nostro team di assistenza esaminerà la vostra richiesta e, se tutto sembra a posto, rimuoverà le restrizioni della porta SMTP per consentirvi di iniziare a lavorare.
Con l'introduzione di questa nuova politica, il nostro obiettivo è quello di bilanciare la necessità di mantenere la nostra piattaforma sicura con la consapevolezza che molti dei nostri clienti hanno necessità legittime di inviare posta. Vogliamo che Linode sia la migliore piattaforma cloud per gli sviluppatori e i clienti per cui costruiscono. Tenendo fuori i malintenzionati e il nostro spazio IP libero da spam e abusi, speriamo di offrire un'esperienza cloud più pulita, più efficiente e, in definitiva, migliore.
Commenti (27)
There’s a confusing discrepancy between this article and the “Running a Mail Server” guide. Here is saying connections to (INCOMING) those ports will be blocked. The guide says OUTBOUND connections will be blocked.
Which is it?
The former makes more sense as it helps stop accidental mail servers on the network. The later doesn’t as it prevent sites/servers from sending emails to administrators. (Like logcheck, update notices for websites, etc.)
Hey Paul. I’ve just updated the post – we block outbound connections on those ports, not inbound connections.
Hi, I don’t understand how this works. I am running OpenVPN on my Linode and when I use it, I can’t email out from thunderbird. Can you explain how I can allow the connections? Because none of this makes sense unless I was using a domain/email
Next step, let ML algorithm decide who to unblock? Anyway, very stupid decision. Customers pay you money. You’re a commodity interchangeable service. If you make stupid additional barriers for customers, they will just live to your rivals. Nobody wants to wait and talk to your support, justify himself and be dependent on someone’s will.
Thank you for sharing your thoughts with us. This policy was created out of a need to address abuse on our platform in a comprehensive way, and we carefully weighed this against industry practices. We are, and always will be, a team of real humans, and we will respond to every request.
If you would like to reach out to us immediately to address these concerns on your account, we are available 24/7 via phone. https://www.linode.com/contact
Can I suggest that moving your main site to Cloudflare may not look the best to some from an anti-spam (and anti-abuse in general) perspective, and perhaps could also suggest to others a possible lack of confidence in your infrastructure’s ability to handle your site’s traffic by itself?
Or could it be in part because your new site has a significantly large bandwidth usage and they help you with the static content bandwidth?
Spammers send mail, that is, make outgoing connections to other mail servers, so I’m not sure how blocking incoming connections helps.
Hey Kenyon. Just updated the post to clarify – we block connections *from* Linodes (e.g. outbound connections), not inbound. Sorry for the confusion!
Ah, but mail servers don’t usually make outgoing connections to ports 465/587…mail client apps do.
I think I understand the change, having seen quite a few SMTP bruteforce attempts in my own mailserver’s logs, but it still doesn’t entirely *fit* the explanation provided.
I think that for many users an intermediate unlock level where 465/587 are allowed but 25 is still blocked would make sense, e.g. if they’re not running a mail server at all but just want to use msmtp for relaying Cron mail through Gmail, or using Amazon SES, or such.
That’s an interesting idea and something we can consider as we review the implications of this change. I appreciate you taking the time to share your thoughts on how to better serve legitimate users. I’ve shared your thoughts with the rest of the company to review.
Port 587 should not be blocked, this port is not used for receiving unauthenticated mail and was created specifically to allow authenticated mail from senders so that networks can block port 25 for non-mail-server traffic.
To be clear, port 587 cannot be used to send spam.
While most mail servers ask for authentication, port 587 can be used as a way to send spam. Port 587 is often used for outgoing unencrypted mail from an SMTP server, and is why we’ve chosen to include it in these ports that are initially blocked.
Good move (both actions), if it helps Linode users running legitimate mail servers getting their non-spam mail accepted on the internet. This has been a problem in the past; also due to other actors (e.g. Google) being entirely non-transparent about how they decide to drop your mail.
When you say we need a valid A record, does that mean we have to use your DNS service in order for the ports to be unblocked? What if we use DNS servers provided by our registrar, a third party, or even a server we operate? Will there be any accommodations for those customers?
You’ll still be able to use whichever DNS servers you like. We can verify valid records using commands like
digin order to validate requests to unblock mail ports. More information about usingdigcan be found via this link.I am curious how do you plan to work this for setups where servers come up and down frequently but have a need to send email when done? Is this going to be an account wide approval or per machine approval?
What is going to be the SLA for response on these requests?
Account wide approval can be done by opening a Support ticket. We work to get to these requests quickly, but if the request is urgent, it’s best to reach us by phone.
I am an existing customer. If I understand correctly I can still provision a new server and not have to contact support to get it unblocked?
Yes, that’s correct! Existing customers do not have to contact support, as mail ports are not blocked by default for them.
Oh cool. I’m sure people are going to be happy to reach out to support immediately after creating an account and waiting hours to actually have full access to the services they’ve paid for.
Such a useless change that will undoubtedly be followed by more. How long until each Linode requires justification?
Hi James! Between actively looking for tickets related to these SMTP restrictions and our 24/7 phone support, we’re able to grab most requests fairly quickly. And I can definitively say that we have no plans to require justification for each new Linode 🙂
Based on what I see in my servers logs, only one way to fight with spam and attack attempts originated from Linode subnets is to block traffic from them. There is no day without attempts:
139.162.204.61 – – [05/Dec/2019:19:28:52 +0000] “GET /api/v1/pods HTTP/1.1” 403 341 “-” “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36”
176.58.124.134 – – [05/Dec/2019:23:46:37 +0000] “GET /msdn.cpp HTTP/1.1” 400 345 “-” “WinHTTP/1.1”
Hey there — our Trust & Safety team has determined that the IP addresses you’re reporting are currently operated by security researchers, and that the associated traffic isn’t intended to be malicious.
Apart from blocking traffic originating from us, we’d gladly pass blacklist requests for your own IP addresses on to our customers — just send the requests to us at abuse@linode.com along with the information you’ve posted here. We monitor this email 24/7, so you can also report any other malicious activity you see coming from our platform there and we’ll quickly investigate.
I feel that this is a good approach, however, those that do have an SMTP server might now know the best ways to fight spam.
Perhaps it would help to have a linked document on best practices, or considerations to keep in mind, emphasising stuff like…
– Establishing and maintaining a secure password policy for e-mail accounts (so passwords can not be ‘123456’ or ‘password’, and some other dumb ones)
– Having an outgoing filter might avoid spam/malware distribution (ie. SpamAssassin, MailScanner, or cloud services like SpamExperts, MailChannels)
– Preventing users from redirecting their inbox to free e-mail providers (or any at all) will also stop spam distribution. Most of these services provide POP/IMAP import which is by far superior to a forwarder
– Enforcing SPF / DKIM on your domains, and outgoing SMTP server. This will make it harder for people to use your domains for phishing, but also will prevent your own server from sending e-mail thru domains you don’t own.
– Setup your SMTP server to reject outgoing e-mail when it belongs to an e-mail address that you don’t own (ie. don’t allow your servers to send e-mail personifying someone else)
– Always use SSL, everywhere, self-signed or free certificates are OK, but not recommended.
Hi Emiliano!
Those are all great points. Thank you for outlining them for people. Linode has a few different email server guides that walk the user through setting things up properly. In particular, the Configure Spam and Virus Protection section of the Running a Mail Server guide, which is linked in the post above. This section goes over a few of the things you’ve mentioned. I can definitely see how helpful it would be to have all of this information in one place. So, I’ve passed your suggestions along to our documentation team for consideration. ?
It would be better if Linode default whitelist certain well-known 3rd party SMTP gateways. For example “email-smtp.us-west-2.amazonaws.com:587” for Amazon SES service.
I mainly use Amazon SES for email because of reliability. After I moved my website to linode, I found that all the email can’t be send because Linode blocked my server connect to Amazon SES gateway. Now I have to open a ticket and wait for unblock, not a smooth experience overall.
Hi Kam,
I’m sorry to hear that you experienced some frustration with this process. We are constantly looking for ways to improve this procedure, and we really appreciate you sharing your thoughts with us. I can definitely understand the validity of your point, so, I’ve passed it along to our team for further consideration.
Please, feel free to share any thoughts you may have about any of our services by sending an email to feedback@linode.com.