It's the serial console.
If you plug in an RS232-to-USB adapter, you should be able to see the console outputs on a PC via PuTTY or any other console app.
There are no standards for RS232 pin configurations on RJ45, though if the adapter works on a Cisco switch, it will usually also work on a no-name doodad such as this one.
The port is unusable as an ethernet port but rather simply a serial port in a modular connector format.
Just to make it clear. The electrical traces aren't plugged into a NIC but a serial one. It uses RJ45 just because it's simply cheaper than having the old serial cables like DB9/RS232.
There are also privative connectors, like famously, the assholes at APC : [Why does a Smart-UPS turn off when a standard serial cable is attached? - APC USA](https://www.apc.com/us/en/faqs/FA156800/)
You can guess how bad it's when your uninterrupted power supply randomly shutdowns, right?
This COM port is usually not connected to a Network Interface Controller (NIC) and can’t be used as an Ethernet port.
It’s just here to provide RS-232 serial connectivity in a more modern, compact and cost effective way than a traditional DE-9M 9-pin port.
It’s used for console management through serial protocol, usually as a last resort if you lose Ethernet network connectivity to the device (unless you’re a network guru and manage network appliance exclusively through serial console).
How do you like them and what are you using them with? Anything notable to share?
I'm new at all this but I put Proxmox on it and I'm trying to use it with a virtualized instance of Opnsense since it seems like there's a lot of power on the table for some other things like pihole etc.
That's super useful info. I appreciate it! Proxmox seems a bit complicated but doable. At the same time I'm considering running Opnsense natively and then just making the switch later.
It just seems like with the N100 I'd be wasting some performance by not using it for other things. Then again, I have an i5-8500T HP micro PC and a dual core J4005 based NAS to pay with. I think I just like to give myself more work to do.
That’s exactly what I’m using it for. It has been awesome for the month I have had it in place. However, as I type this, I am currently away on vacation and my internet just went down at home. So, I am anxious to get home and see if it is a problem with this setup or something else!
No, do not use it as a nic.
Its the console port which is used by specific use cables such as [this one](https://www.startech.com/en-ca/cables/db9concabl6)
Yeah I did have one exactly the same color and for the sake of Hermes I couldn’t have remembered why did I have it and got rid of it while I was doing my cleaning up session every couple or so years! Haha definitely the best color!
I just purchased this unit and it comes with an Intel N100, and four Intel I226V 2.5G NICs. I notice I have an extra COM port. What is the purpose of this exactly? Can I theoretically use this as a fifth (probably slower) NIC? I can't seem to find it in Proxmox. Otherwise, what is the purpose of this?
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Like others have mentioned, it's a serial port to configure the device. You can usually configure the device from a web interface connecting to the LAN ports, to whatever IP it uses as default after reset, [192.168.100.1](http://192.168.100.1) for example.
The COM port is in case the web interface is disabled, then you would have to have physical access to the device to configure it. In the manual you might see mentions of Baud Rate for this port. You have to set this to match the port when connecting with a Serial Console program like PuTTY, among other settings like parity and stop bits. These ports are very common on switches, routers, firewalls et cetera.
You can not use this for Ethernet.
I got this one off ali a few months back (N100 DDR 5): [https://www.aliexpress.us/item/3256804173757529.html?spm=a2g0o.order\_list.order\_list\_main.5.23881802hz63YX&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256804173757529.html?spm=a2g0o.order_list.order_list_main.5.23881802hz63YX&gatewayAdapt=glo2usa)
I use it with proxmox+opnsense. Zero issues.
It does run warm so I 3d printed this guy: [https://www.thingiverse.com/thing:6104610](https://www.thingiverse.com/thing:6104610)
and hooked up a fan using this guy: [https://www.aliexpress.us/item/3256805848231377.html?spm=a2g0o.order\_list.order\_list\_main.10.23881802hz63YX&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256805848231377.html?spm=a2g0o.order_list.order_list_main.10.23881802hz63YX&gatewayAdapt=glo2usa)
and its all gravy!
If I'm not mistaken, there is a fan socket near the Sata power on the mother board, maybe worth checking out for you!
Thanks for the haste response, you helped a lot!
Mine just got in yesterday. I was surprised I could fit a whole 2.5" ssd in there. I have a similar one running pfSense on Proxmox and they both run hot since they have no internal fan. I just have a usb powered 120mm fan on top and it's fine.
I just put an SSD in one of mine today. I too was shocked! It even has nice screw holes in the bottom of the case to secure the SSD. The cables were snug, but worked.
I have this lil guy, or one of it's siblings with an N100. So your options will very with what CPU you have. With the N100, you can change the settings in the BIOS. It can be a serial port or console.
EDIT: Just kidding. I looked at that one quite a bit but went with this one...
https://www.ebay.com/itm/355177886744?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=4jxvchf-tdu&sssrc=4429486&ssuid=yyFgFeT8R3i&var=624412079517&widget_ver=artemis&media=COPY
^(USB/USB - okay, serial? ETH? I assume the blue ones are for serial console?)
^(Wifi and Wifi - okay, wwan? I assume one is - since there is a SIM above it. Could one be LTE? Gee...)
^(The COM is definitely serial console. Just a fail at labeling.)
^(Oh, I am so glad I don't have to read the manual that comes with that cheap device.)
You might be able to manage your network if it goes out of band using the LTE with a working SIM. Possibly only need a data SIM to provision a public IP you can hit using SSH, but I could be giving this device too much credit. It could be a KVM what with the DP and HDMI ports. It looks like a cheap doo-dad that wouldn't be reliable in an enterprise, but for a home network full of other inexpensive stuff.
There is likely an RJ-45 to serial cable you will use to use this com port. No, cannot use as you would the other ethernet ports. Only a serial connection made to go over an RJ45 port.
Looks like the one I got off ali (n100 version): [https://www.aliexpress.us/item/3256804173757529.html?spm=a2g0o.order\_list.order\_list\_main.5.23881802hz63YX&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256804173757529.html?spm=a2g0o.order_list.order_list_main.5.23881802hz63YX&gatewayAdapt=glo2usa)
Works great.
Similar to the other guy I got [this one](https://a.aliexpress.com/_mMJwTlU) in an 8gb DDR5 256gb nvme SSD config. I was pleasantly surprised to find a name brand Kingston SSD and Lenovo ram.
Well, it's for remote management of a matrix terminal circa telegram when having your hand physically in the machine itself was the norm and a wire used to communicate was considered remote.
Should be a serial management console.
It's the serial console. If you plug in an RS232-to-USB adapter, you should be able to see the console outputs on a PC via PuTTY or any other console app. There are no standards for RS232 pin configurations on RJ45, though if the adapter works on a Cisco switch, it will usually also work on a no-name doodad such as this one. The port is unusable as an ethernet port but rather simply a serial port in a modular connector format.
Short answer: no
Just to make it clear. The electrical traces aren't plugged into a NIC but a serial one. It uses RJ45 just because it's simply cheaper than having the old serial cables like DB9/RS232. There are also privative connectors, like famously, the assholes at APC : [Why does a Smart-UPS turn off when a standard serial cable is attached? - APC USA](https://www.apc.com/us/en/faqs/FA156800/) You can guess how bad it's when your uninterrupted power supply randomly shutdowns, right?
I literally did this the other day, totally embarrassing. Now I know.
I did it about 6 years ago. Don't feel bad, most of us learn it this same way.
Real asshole design by apc
This COM port is usually not connected to a Network Interface Controller (NIC) and can’t be used as an Ethernet port. It’s just here to provide RS-232 serial connectivity in a more modern, compact and cost effective way than a traditional DE-9M 9-pin port. It’s used for console management through serial protocol, usually as a last resort if you lose Ethernet network connectivity to the device (unless you’re a network guru and manage network appliance exclusively through serial console).
I have two of these. COM is the serial interface. Cannot use it as a NIC.
How do you like them and what are you using them with? Anything notable to share? I'm new at all this but I put Proxmox on it and I'm trying to use it with a virtualized instance of Opnsense since it seems like there's a lot of power on the table for some other things like pihole etc.
If you're running opnsense, there will be zero need for pihole. Just sayin.
That's super useful info. I appreciate it! Proxmox seems a bit complicated but doable. At the same time I'm considering running Opnsense natively and then just making the switch later. It just seems like with the N100 I'd be wasting some performance by not using it for other things. Then again, I have an i5-8500T HP micro PC and a dual core J4005 based NAS to pay with. I think I just like to give myself more work to do.
That’s exactly what I’m using it for. It has been awesome for the month I have had it in place. However, as I type this, I am currently away on vacation and my internet just went down at home. So, I am anxious to get home and see if it is a problem with this setup or something else!
That’s likely your console port.
No, do not use it as a nic. Its the console port which is used by specific use cables such as [this one](https://www.startech.com/en-ca/cables/db9concabl6)
Yeah I did have one exactly the same color and for the sake of Hermes I couldn’t have remembered why did I have it and got rid of it while I was doing my cleaning up session every couple or so years! Haha definitely the best color!
Nope.
No
No it can not be used as a NIC. It is a serial port. You can access the console with a serial cable and putty, see what's going on behind the scenes.
I guess if youre happy with 0.25Mb/s sure
I just purchased this unit and it comes with an Intel N100, and four Intel I226V 2.5G NICs. I notice I have an extra COM port. What is the purpose of this exactly? Can I theoretically use this as a fifth (probably slower) NIC? I can't seem to find it in Proxmox. Otherwise, what is the purpose of this?
It's to directly connect to its terminal and config it instead of via lan. And it's very likely you can't use it as a normal Ethernet port.
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Like others have mentioned, it's a serial port to configure the device. You can usually configure the device from a web interface connecting to the LAN ports, to whatever IP it uses as default after reset, [192.168.100.1](http://192.168.100.1) for example. The COM port is in case the web interface is disabled, then you would have to have physical access to the device to configure it. In the manual you might see mentions of Baud Rate for this port. You have to set this to match the port when connecting with a Serial Console program like PuTTY, among other settings like parity and stop bits. These ports are very common on switches, routers, firewalls et cetera. You can not use this for Ethernet.
I'm planning to buy that as well! Have you received it already? Any insight? What are you planning to use it for? Would like to hear your opinion!
I got this one off ali a few months back (N100 DDR 5): [https://www.aliexpress.us/item/3256804173757529.html?spm=a2g0o.order\_list.order\_list\_main.5.23881802hz63YX&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256804173757529.html?spm=a2g0o.order_list.order_list_main.5.23881802hz63YX&gatewayAdapt=glo2usa) I use it with proxmox+opnsense. Zero issues. It does run warm so I 3d printed this guy: [https://www.thingiverse.com/thing:6104610](https://www.thingiverse.com/thing:6104610) and hooked up a fan using this guy: [https://www.aliexpress.us/item/3256805848231377.html?spm=a2g0o.order\_list.order\_list\_main.10.23881802hz63YX&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256805848231377.html?spm=a2g0o.order_list.order_list_main.10.23881802hz63YX&gatewayAdapt=glo2usa) and its all gravy!
If I'm not mistaken, there is a fan socket near the Sata power on the mother board, maybe worth checking out for you! Thanks for the haste response, you helped a lot!
There is. This was just easier with the 3d printed case and the particular fan I had laying around.
Mine just got in yesterday. I was surprised I could fit a whole 2.5" ssd in there. I have a similar one running pfSense on Proxmox and they both run hot since they have no internal fan. I just have a usb powered 120mm fan on top and it's fine.
I just put an SSD in one of mine today. I too was shocked! It even has nice screw holes in the bottom of the case to secure the SSD. The cables were snug, but worked.
I have this lil guy, or one of it's siblings with an N100. So your options will very with what CPU you have. With the N100, you can change the settings in the BIOS. It can be a serial port or console. EDIT: Just kidding. I looked at that one quite a bit but went with this one... https://www.ebay.com/itm/355177886744?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=4jxvchf-tdu&sssrc=4429486&ssuid=yyFgFeT8R3i&var=624412079517&widget_ver=artemis&media=COPY
^(USB/USB - okay, serial? ETH? I assume the blue ones are for serial console?) ^(Wifi and Wifi - okay, wwan? I assume one is - since there is a SIM above it. Could one be LTE? Gee...) ^(The COM is definitely serial console. Just a fail at labeling.) ^(Oh, I am so glad I don't have to read the manual that comes with that cheap device.) You might be able to manage your network if it goes out of band using the LTE with a working SIM. Possibly only need a data SIM to provision a public IP you can hit using SSH, but I could be giving this device too much credit. It could be a KVM what with the DP and HDMI ports. It looks like a cheap doo-dad that wouldn't be reliable in an enterprise, but for a home network full of other inexpensive stuff.
There is likely an RJ-45 to serial cable you will use to use this com port. No, cannot use as you would the other ethernet ports. Only a serial connection made to go over an RJ45 port.
Name of device?
Looks like the one I got off ali (n100 version): [https://www.aliexpress.us/item/3256804173757529.html?spm=a2g0o.order\_list.order\_list\_main.5.23881802hz63YX&gatewayAdapt=glo2usa](https://www.aliexpress.us/item/3256804173757529.html?spm=a2g0o.order_list.order_list_main.5.23881802hz63YX&gatewayAdapt=glo2usa) Works great.
Looks much like something from Qotom
Similar to the other guy I got [this one](https://a.aliexpress.com/_mMJwTlU) in an 8gb DDR5 256gb nvme SSD config. I was pleasantly surprised to find a name brand Kingston SSD and Lenovo ram.
Remote management.
Well, not remote. On-site management to directly connect to it with a serial cable 😅
Well, it's for remote management of a matrix terminal circa telegram when having your hand physically in the machine itself was the norm and a wire used to communicate was considered remote.
Grandpa tells.