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Ally04
Aspirant

filtered ports

How do you configure the netgear router so that open ports 25 & 110 for the mail server appear filtered rather than open.

Message 1 of 7
DaneA
NETGEAR Moderator

Re: filtered ports

Hi Ally04,

 

What specific Netgear device do you have?  

 

I look forward to your response.  Welcome to the community! Smiley Happy

 

 

Regards,

 

DaneA

NETGEAR Community Team

Message 2 of 7
JennC
NETGEAR Employee Retired

Re: filtered ports

Hello Ally04,

 

Welcome to the community!

 

There is only an option to open a port for a specific WAN IP address on the Internet.

 

Regards,

JennC
NETGEAR Community Team
Message 3 of 7
Ally04
Aspirant

Re: filtered ports


@DaneA wrote:

Hi @Ally04,

 

What specific Netgear device do you have?  

 

I look forward to your response.  Welcome to the community! Smiley Happy

 

 

Regards,

 

DaneA

NETGEAR Community Team


Hi DaneA,

 

My device is WNDR3400v3. I have managed to open the port 25 for the incoming and outgoing mails using the port forwarding option. However, since the status of the port appears open, I am having a lot of spammers trying to relay mails through my mail server despite the server not allowing relays. Is it therefore possible to configue the netgear so that the port appears filtered or cloaked so that it does not respond to port scanners?

 

Regards

Ally

 

Message 4 of 7
TheEther
Guru

Re: filtered ports

Short answer is, no, there's nothing on the WNDR3400v3 that can partially cloak an otherwise open port.

 

You could gain some measure of control with a firewall that could expose ports to specific, whitelisted external IP addresses.  Alas, the WNDR3400v3 can't do that.  Since email can come from anywhere, it would also be a pain to maintain.

 

IMHO, you should rethink your email setup.  Are you running your own email server?  If so, do you really need it?

 

Or are you sending and receiving mails through a regular email client?  If it's a browser-based email client, then you don't even need to open port 25 in the first place, as it generally runs through https (port 443).

 

If you are running an IMAP or POP client, then you still shouldn't use port 25.  As you have discovered, port 25 is essentially unusable in the Internet.  There are better ports to use for email, such as 465 and 587, both of which are secure.  Moreover, you don't need to open any ports on the router because clients generally pull email.

 

Finally, apologies if you already know all this.

Message 5 of 7
Ally04
Aspirant

Re: filtered ports

Dear TheEther,

 

Thanks for the guidance but it still hasnt solved my problem.

 

As you said "You could gain some measure of control with a firewall that could expose ports to specific, whitelisted external IP addresses. Alas, the WNDR3400v3 can't do that.  Since email can come from anywhere, it would also be a pain to maintain."

 

It will therefore not be workable for me to keep it open to only specific whitelisted addresses.

 

Yes we do require the mail server for our oranisation as most of our communication is through e-mail, in which case we do need the port 25 open for the smtp service.

 

The e-mail clients are on the individual computers and access the mails from the server via POP over the LAN. This therefore requires port 110 but only internally & not externally.

 

Thanks for your help.

 

Regards

Ally

 

Message 6 of 7
TheEther
Guru

Re: filtered ports

If your email server is the primary MX for your domain, then I don't think there's anything you can do to block port 25 from spammers. You'll have to find some other way to block them (e.g. Spam blacklists like spamhouse.org or similar).

You could also move your primary MX off of your network to an email provider that is more capable of managing spam. You could set up a local MDA to pull emails from the provider and function as a local POP server.

Disclaimer: I'm not an expert at setting up email infrastructure, so take what I say with a grain a salt. You'll want to do your own research to find the solution that best fits your needs and budget.
Message 7 of 7
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