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Which TCP Ports to Open on a Firewall

By wwhitred ·
What ports should be open on a typical firewall (if there is such a thing)? Right now I can't open hyperlinks from within a web page. Is a simple to understand reference I can access?

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by jschein In reply to Which TCP Ports to Open o ...

all ports should start off blocked and work your way out from there...

open 80 from inbound to outbound - web surfing...

then basically, just watch your logs on your firewall to see what gets blocked and unblock as needed.

it's pretty simple. good luck

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by Curacao_Dejavu In reply to Which TCP Ports to Open o ...


in the future pls include the version of windows and the version of the program (IE in this case).
I think the problem is not the (a) firewall.

1: go to control panel , add remove programs, IE and do a repair.
2: go to (hmm) i guess upgrading to IE 6 and patches wont help via the web.

I am seeing to only reference to this problem for macinthos.
download ad aware:
to see if you have spy ware on your pc, and uninstall unnessary programs.


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by mark.denny In reply to Which TCP Ports to Open o ...

Theirs not a complete standard but you could use the following as some guidelines as to what you ports you may want to close or to open up.

Port 80 for HTTP web traffic.
Port 443 for HTTPS web traffic.
Port 25 for SMTP email traffic.
Port 21 for FTP traffic.
Port 53 for DNS lookups.

These basic ports will allow your users to send and receive email from a central server if they need to. Got to websites which use the standard http protocol and https protocal (secure websites use this). You need may need to allow your users ftp and dns lookup traffic but that depends on your setup.

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by Legion_96 In reply to Which TCP Ports to Open o ...

I recommend these sites for further reference.
If by chance your running a Windows OS check : Url=/technet/prodtechnol/windows2000serv/reskit/tcpip/part4/tcpappc.asp

Typical Open Ports
In addition to thoses listed in prior responce.
Port/Protocol: 445/TCP
Description: Direct Hosting of SMB over TCP/IP (MS Windows 2000 Services). The SMB (Server Message Block) protocol is used with NetBios for file sharing.
Port/Protocol: 139/TCP
Description: NetBIOS Session Services are part of the NetBIOS over TCP/IP (NetBT) family of protocols and is used for server message block (SMB), file sharing, and printing

Port/Protocol: 138/TCP
Description: The NetBIOS Datagram is part of the NetBIOS over TCP/IP (NetBT) family of protocols and is used for network logon and browsing

Port/Protocol: 137/TCP
Description: The network basic input/output system (NetBIOS) Name Server (NBNS) protocol, which is part of the NetBIOS over TCP/IP (NetBT) family of protocols, provides a means for hostname and address mapping on a NetBIOS-aware network

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by -Q-240248 In reply to Which TCP Ports to Open o ...

OMG! Depends on the firewall, whether it is stateful or not. DO NOT OPEN UP ANY PORTS UNTIL YOU KNOW WHAT FIREWALL IT IS! Normally, today's firewalls do NOT REQUIRE any ports to be open in order to access a website from the inside to the Internet. If you open ports, both inbound and outbound, you've just allowed everyone in. Sure, open port 80, and watch your PCs and servers get attacked! Don't open anything until you get professional help...

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