Welcome to the Forum!

I have two SE's and the are connected to the internet. Both have an ethernet card. They are not simple to find.

A meber found one on Ebay:

http://68kmla.org/forums/viewtopic.php?f=7&t=15102

You can set up a PPP connecting true a null modem to your Linux box. See:

viewtopic.php?t=1393

Or buy a DaynaPORT/ SCSI Ethernet adapter:

http://68kmla.org/forums/viewtopic.php?f=7&t=11601&p=140915&hilit=daynaport+scsi#p140915

Just look around on the forum and you will fins lots of information!