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Ports to block security

Posted on 2015-02-18
Last Modified: 2015-03-26
hey guys,

i have a cloud server, and i'm looking for a list of essential ports to block to keep it safe. This wont be anything production so its not a big deal, but looking for a basic list.

Question by:Cobra25
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LVL 29

Expert Comment

ID: 40618243
What does your server do?  You're going about it backwards.  The standard practice is to block everything except the ports you want running.

If you're running  a web server, you'd leave port 80 and port 443 or just port 443 open.  You probably want to RDP to it, so you should open a port for RDP, although I suggest not using the standard port, unless you only allow certain known, fixed IPs through.

Author Comment

ID: 40618248
ok, im looking for standard ports to block please thats all.
LVL 29

Expert Comment

ID: 40618252
Block ports 137, 138, 139, and 445

It's still better to block everything and whitelist the ones you want.  It prevents random software from opening ports on you without your knowledge.
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Author Comment

ID: 40618263
thanks serial! what ports does SQL use? any other ports? are those all TCP or UDP?

Kind of doing an experiment here.
LVL 29

Expert Comment

ID: 40618315
They're a mix.

UDP on 138
TCP on 139
both on 137 & 445

SQL on 1433, and client ports are assigned a random value between 1024 and 5000.

Author Comment

ID: 40618316
I thought SQL used more than 1 port.

Client ports I'm not concerned with

Accepted Solution

Monika Bharti earned 500 total points
ID: 40618538

You have to start from all these essential ports to block security.

Port 19 (Chargen)
Blocked Inbound
This port is blocked the incoming service to enter in campus network.

Port 123 (NTP)
Blocked unapproved Server from In
This port is connected with NTP (Network Time Protocol). Due to continuing security weaknesses, incoming networks are only acceptable to connect to support NTP servers of campus.
Ports 135, 137, 138, and 139 (TCP and UDP Microsoft NetBIOS)
Blocked In and Out both services
In file sharing and windows file for windows NT/ME/98/95, these ports are used including Exchange Server and MS Outlook clients.

Ports 161-162 (SNMP)
Blocked only In service
These ports are generally used by SNMP (Network Monitoring Protocol). Due to continuing (ongoing) security liabilities, these ports are allowed to exit and blocked to enter in the campus network.
Port 445 TCP and UDP
Blocked In and out both service
For file sharing of Windows XP/2000 & 2003 these ports are used.
Ports 41170 and 1434 (Denial of service file sharing)
Blocked Both in and out
These ports are used DOS service for file sharing.
LVL 29

Expert Comment

ID: 40618769
You're right.  I found the SQL port information from this site

UDP port 1434
TCP port 1433
TCP port 433
TCP port 4022
TCP port 135

@Monika If you're going to cut and paste full text someone else's information from what appears to be some college website, please at least link to it and quote it.  They deserve some credit.

Author Comment

ID: 40624463
Thanks guys!

Any others were missing?

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