General Knoppix support for those who've read the FAQ at the Wiki

SFP TO RJ45 TRANSCEIVER SFP MODULE COPPER SFP OPTICAL PORT TO RJ45 ETHERNET PORT
$7.99
NEW Sealed Cisco SFP-10G-LR 10GBASE-LR SFP+ 1310nm 10km *US Shipping*
$24.00
Intel SPTSLP2SLCDE 100G-DR1 QSFP28 500m 1311nm Transceivers - Lot of 10 - New
$200.00
Cisco QSFP-40G-SR-BD Module 10-2945-02 NEW CLAMSHELL
$45.50
Genuine Cisco SFP-10G-SR 0-2415-03 10 Gigabit Transceiver
$5.40
HP 560SFP+ 10GB 2-port PCIe NIC Ethernet ADAPTER 669279-001 w/ (2) 10GB SFP+
$16.99
Intel X520-DA2 10Gb 10Gbe 10 Gigabit Network Adapter NIC Dual Port E10G42BTDA
$28.94
Lot of 68 Cisco DS-SFP-FC4G-SW SFP Fiber Transceiver 850nm 10-2195-01
$136.00
Cisco Acacia DP04QSDD-E25-840 400G QSFP-DD Coherent DCO Transceiver Module
$699.99
Cisco WS-C3650-12X48UR-L 48-Port Stackable Layer 3 8x10G SFP+ Port Switch
$129.99