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I have an aging Windows XP PC whose purpose is to feed code to a manufacturing machine via a RS-232 connection using machine-specific software. The PC needs to retrieve its code from a network file share. This PC came with the manufacturing machine (purchased used), and I do not have / cannot obtain its administrator password. Furthermore, the PC has automatic updates disabled and its firewall disabled and these cannot be turned on without admin access. I am concerned about the security risk of having an un-updated / un-firewalled PC on my network.

Can I somehow secure this machine through settings on our Cisco managed switch (SG300) in order to limit it to its one and only network related task - which is to connect to a network file share? The machine does not need internet access. It only needs access to a single network file share. Is there a way this can be done?

Here is more detailed info about our network configuration:

  • The managed switch is a Cisco SG300. It is handling all Layer 3 switching.
  • The file server is connected to the Cisco SG300 switch.
  • The router is a Ubiquiti Edgerouter X, however I believe this is out of the picture because the Cisco switch is doing all internal switching and handling Vlans.
  • The aging PC is connected to the network via Wifi.
  • The aging PC does not have a Wifi card, so it is connecting to Wifi via a wired-ethernet to wifi adapter (IOGear GWU627W6).
  • The wireless access point is a Ubiquiti Unifi AP-LR, which is connected to the Cisco SG300 switch.
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    We need more information. At least a good description of the network, the network device models, and the network device configurations. Refer to the Network Engineering Question Checklist for guidance, then edit your question. – Ron Maupin Dec 4 '18 at 15:06
  • Basically the only thing you could do on the switch is VLAN segmentation. With this, you would have a seperate logical broadcast domain but no chance to control the traffic like a firewall does. Furthermore you would need something for routing. As Ron already wrote we need some more details. If you have a firewall in your network, a simple solution could be to do basic stateful packet inspection between your WinXP PC (which is in a seperate VLAN) and the file server. – Markus Dec 4 '18 at 15:20
  • Hello PMetal and welcome to Network Engineering. What manufacturer and model of switch is Aging PC plugged into? Is server on same switch? – jonathanjo Dec 4 '18 at 16:11
  • We still need the network device configurations. It sounds like you need a separate SSID and VLAN for the PC (much like a guest SSID and VLAN), which you can then use ACLs to restrict access, but we cannot help unless you give us enough information. – Ron Maupin Dec 4 '18 at 16:37
  • Thank you for your input - I have updated the original post with additional network details. I like the idea to use a separate VLAN to separate it. I could certainly use a separate SSID for this machine as well. – PMetal Dec 4 '18 at 16:41
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  • Consider adding MAC based access-control lists to your switch. This will make it so that Aging PC can only send and receive frames to and from the server
  • Consider IP address and port ACLs, so it can only do file-share related tasks even with this server
  • Consider changing Aging PC to wired: then only frames have to go through the switch to the PC
  • Consider putting Aging PC's wifi in a SSID of its own, if you can't make it wired
  • Consider direct wire from PC to second NIC on server, with otherwise unrouted IP address
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