X3270 opens a telnet connection to an IBM mainframe host in an X11 window. It can also connect to an IBM AS/400 as a 5250 terminal using the AS/400's 3270 emulation. The window created by x3270 can use its own font for displaying characters, so it is a fairly accurate representation of an IBM 3278 or 3279.
x3270 is similar to tn3270(1) and c3270(1) except that it is X-based, not curses-based.
x3270 implements RFCs 2355 (TN3270E), 1576 (TN3270), and 1646 (LU name selection), and supports IND$FILE file transfer.
You will need to install x3270's fonts locally, or on your font-server - they are required.