ports used for file sharing? Solved

Question

Hello,

I replaced my Filseclab firewall with Look'n'stop because Filseclab was preventing Apache from starting. I'm configuring Look'n'stop bit by bit.

I'm currently at the Windows file sharing stage and I would like to understand which ports are used: I found on a Microsoft support site that ports 137 to 139 are used in TCP and UDP, but apparently that’s not enough. I had to create a rule to allow ICMP packets with "code 0 and type 8", as well as rules for UDP ports 1345 to 1348.

Anyway, I really don't understand which ports are essential for file sharing.

Does anyone know of a tutorial or a site with a clear and, above all, comprehensive explanation on this subject?

Thanks in advance

Configuration: Windows XP SP2 Firefox 2.0.0.9 look'n'stop 2.06

Younes Rohani · Accepted Answer

UDP ports 137, 138, and 139 are used for resource sharing in Windows operating systems. When a workstation connects to a shared directory on another machine, the NetBIOS name of the server machine is matched with its IP address. Then, the workstation establishes a TCP connection to the server machine using TCP port 139. Finally, the workstation sends a NetBIOS session request to the server machine. If the server is listening, it will respond to the request, and the NetBIOS session will be established. However, if the server does not respond or if the server workstation is turned off, the session will attempt to connect to hypothetical external servers (on the INTERNET). Port 138 is used for data exchange to one or more NetBIOS names grouped under an address list or in a broadcast list.

That's why 4 ports ;)

Smart91 · Answer

Good evening,

I don’t understand why you want to share your files over the internet. File sharing is done at the local network level. Of course, it can be done over the internet, but it's better to use a VPN solution in that case.

Smart
--

"If you have no ambitions, you settle down at the edge of the abyss" (Kundera)

led · Answer

Thank you for your response Smart,

No, I don't want to share them over the internet: it's just that I have two PCs on a local network, and on PC1 (the one I work on most of the time) I've installed the Look'n'Stop firewall. But PC2 needs to access files stored on PC1. And the firewall on PC1 is blocking access.
On the other hand, I'm sure that this is the issue because when I disable the "internet filtering" (in the firewall jargon, but it's just the filters on incoming connections), access to files on PC1 from PC2 works fine.

There you go, I hope it's clearer like this :-)

Smart91 · Answer

So at the level of your personal firewall, allow the IP addresses of your two other PCs  Smart --  "If you have no ambitions, you settle on the edge of the fall" (Kundera)

Sergio · Answer

Hello,

I’m bringing up the topic again, not for practical reasons but for theoretical ones.

I would really like to know which ports are used for file sharing under Windows. I haven't found any explanations online about which port serves what purpose, and I really want to understand.

Ports 137, 138, 139, and 445 are all associated with Windows file sharing, but in my opinion, one port should be sufficient... Why four?

And also, does anyone know exactly what protocol is used? Is it SMB? Or a slightly different Windows version of SMB? And when you type \\<DNSname> or \\<IP>:
What command is sent?
On which port?

If anyone has the answers, it would be greatly appreciated!

Best regards, Serge

Beria · Answer

Hello,

http://www.looknstop.com/Fr/rules/rules.htm

File sharing on a local network

To enable file sharing between computers on a local network, import the 3 UDP rules: Sharing, TCP: sharing 1, and TCP: sharing 2 from the file partage.rie onto the PCs in the local network.

Warning: this rule is suitable if the IP addresses of the PCs in your network are of the type 192.168.x.y
Otherwise, modify the 3 rules with your subnet IP address.

"a rule to allow ICMP packets of "code 0 and type 8""

If you have allowed type 8 code 0, remove it immediately.

As a general rule, when traffic is blocked, to allow it, right-click in the log and accept the "client" rule, if you are sure of what you are doing, of course.

Ports used for file sharing?

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