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I am using a client computer, my server runs Win2008 server, and I am granted all privileges to be an administrator of my own computer :rolleyes: The admin blocked some ports in the server so that I can't access to particular chat system or webpages. I would like to know if there is any way/method I can follow to trace out what ports have been blocked from my client computer.

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We block all out bound ports except those specifically needed to meet a particular business need. That means 80, 443 are generally open and 25 from the mail servers only. others on an as needed basis. – uSlackr Feb 25 '12 at 14:57
I know the business needs to blocking particular ports, I would like to know if there is any way I can see which have been blocked from my client computer. – Thach Xuyen Feb 25 '12 at 15:05

You don't say why you want to know this, but if you really want to know they ask your administrator.

Note, blocking ports and blocking webpages are two completely different things. Most administrators don't block specific ports, but rather everything is blocked by default and they only enable those that are needed. Most administrators would see this as standard procedure in order to keep their server secure.

Blocking webpages is not about keeping a server secure, but is usually done to stop employees/users from wasting time on the internet or accessing illegal websites (eg porn on a school computer) and such action is usually as a result of a request from management rather than IT. Not always, as some administrators might decide to block, for example, youtube if users were downloading so many videos that it was causing problems for people using the internet for proper business use.

Blocking websites is occasionally done by blocking everything and then allowing only a specific number of sites, but it is more common for everything to be enabled by default except for specific sites. (eg if employees are spending too much time on Facebook, then social websites are often blocked).

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So that means there is no way (commands, tools) I can see what ports are blocked ? – Thach Xuyen Feb 25 '12 at 15:04
There is no simple way, except to try it. For example, to send email through gmail's servers you don't use port 25, but port 465 or 587, so if I wanted to tell whether this was blocked by my firewall I would type telnet 465 or telnet 587 and see if it responds. But this requires me to know what I expect to see. In this case I expect to see a 220 message indicating I am talking to a mail server. However, I could try this on a million servers and they could all fail because they don't use this port, so until I try gmail it may look like this port if blocked. – sgmoore Feb 25 '12 at 15:23
By the way, telnet is part of windows but is now longer installed as standard. If you want it, you need to select it from Control Panel/Programs and Features/Turn Windows Features on and off and then select 'Telnet client' – sgmoore Feb 25 '12 at 15:27

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