Since the start of 2007, we have had a number of customers experience issues with connecting to the Plesk Control Panel on their allocated server, while having no problem connecting to their site or the server in general. This normally occurs around Peak-time hours (17:00 to 23:00) on weekdays, and sometimes longer on weekends.
This is in fact nothing to do with us, but rather draconian restrictions placed on customers' connections in an attempt to stop, or at least minimize, P2P traffic via their network.
Generally, anything that isn't on one of the following ports will most likely be blocked:
- HTTP (Port 80) & HTTPs (Port 443)
Some customers on some providers have reported problems with HTTPs traffic as well. - POP (Port 110)
The secure version (POPs, Port 995) is usually blocked. - IMAP (Port 143)
The secure version (IMAPs, Port 993) is usually blocked. - SMTP (Port 25)
The secure version (SMTPs, Port 465) is usually blocked, although TLS connections are unaffected as they use the standard port. - FTP (Port 21)
Although the main communication channel may be fine, the data channels used for transferring files and directory listings may be restricted (especially for uploads). - SSH (Port 22)
This is by no means an exhaustive list, nor is it a guarantee that all companies will provide access to those ports. Through research, these seam to be the main ports unaffected (at least partially) by the clamp down.
Also, the following ISPs are known (or at least appear) to implement this policy at this time:
- Tiscali (IPStream, not Datastream customers)
- Virgin (although this seams to be very few customers
If you are having problems connecting to Plesk in the evening, please do contact us to make sure it isn't a server issue. However, if it is a regular occurrence during the evenings, you may find yourself affected by this new, emerging, policy being implemented by some IPSs.
