2 Messages
Outgoing TCP requessts on port 25 are blocked completely
How can I get outgoing requests on port 25 to be unblocked for small business fiber internet?
Additionally, how can I request a PTR/reverse DNS record to be added to one of my static IP addresses?
My account has 5 usable static IPs and is not a residential account, so port 25 should not be blocked.
ATTHelp
Community Support
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232.9K Messages
1 month ago
Hi @ssorkin
We understand your concern. Let's get the help you need.
The Community Forums are a public support option where other users, and AT&T, will try and assist with high level support needs. This means we won’t be able to look into account specific concerns. To get the help you need for your Business Account, please review our https://bizcommunity.att.com/, and choose the best option to reach out to us.
Thank you for choosing AT&T.
Maria, AT&T Community Specialist.
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receding_hairline
Employee
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212 Messages
1 month ago
As noted above, AT&T blocks certain ports that transfer malicious or disruptive traffic to protect our customers and our network. Below is more information about port blocking that is currently in place. We may block additional ports in the future based upon threat assessments.
Port
Transport
Protocol
Direction
Threats
0
TCP
Reserved
Both
Reserved Port
19
UDP
Chargen
Both
Reflective DDOS
25
TCP
SMTP
Outbound
SPAM, Malware
68
UDP
BOOTP
Outbound
DHCP server spoofing
123
UDP
NTP
Both
Reflective DDOS
135
TCP
NetBios
Both
Worms, Malware, Reflective DDoS
139
TCP
NetBios
Both
Worms, Malware
445
TCP
MS-DS SMB
Both
Worms, Malware
520
UDP
RIPv
Both
Reflective DDOS
1900
UDP
SSDP
Both
Reflective DDOS
3479
TCP
Twrpc
Both
End user device instability
7547
TCP
CWMP
Both
End user device instability
49152
TCP
Dynamic
Inbound
Unauthorized access, DoS
49955
TCP
Dynamic
Inbound
Unauthorized access, DoS
50001
TCP
Dynamic
Inbound
Unauthorized access, DoS
51001 - 51003
TCP
Dynamic
Inbound
Unauthorized access, DoS
51010 - 51012
TCP
Dynamic
Inbound
Unauthorized access, DoS
51020
TCP
Dynamic
Inbound
Unauthorized access, DoS
61001
TCP
IPDR
Both
Data exposure, end user device instability
Port 25/TCP: Simple Mail Transport Protocol (SMTP) is used to send email. Port 25/TCP may be blocked from customers with dynamically-assigned Internet Protocol (IP) addresses to protect systems from becoming a mail relay for SPAM. Customers can subscribe to AT&T SMTP services if they need to host an SMTP server on the internet.
source: https://about.att.com/sites/broadband/network
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ssorkin
2 Messages
1 month ago
As I originally mentioned, this is a small business account, and it does have a set of 8 (5 usable) static IP addresses assigned to it. However, I have not been able to find the way to request the port to be unblocked.
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thechef1
Tutor
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484 Messages
1 month ago
>My account has 5 usable static IPs and is not a residential account, so port 25 should not be blocked.
You will have to wait for your inquiry to be responded to in the biz forum (I see you posted there).
The port will be blocked by default, even if you have 5 usable static IPs. AT&T Support will have to address that.
This is usually done by some AT&T tech eventuallly telling you to DM them.
You can also call support and when Tier 1 gives you the run around, ask to have your call escalated.
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