set interface duplex
 

I am using redhat 7.3 and need to confirm my network card duplex settings (10 half, 100 full). I am getting errors on the console that 'may be mismatch duplex settings'. I do not have any x windows installed and ifconfig and netconf do not seem to have the options. Thanks

Try mii-tool
here is what I use to set my 100mbit card down to 10mbit Full Duplex(Bad Port on my Router)

mii-tool -A 10baseT-FD