http://www.uni-leipzig.de/urz/wlan/

network={
        scan_ssid=1
        ssid="802.1X"
        key_mgmt=WPA-EAP
        eap=TTLS
        identity="*****"
        password="*****"
        anonymous_identity="anonymous"
        phase1="peaplabel=0"
        phase2="auth=PAP"
}

auto lo eth0
iface lo inet loopback
iface eth0 inet dhcp
iface eth1 inet dhcp

wpa-conf /etc/wpa_supplicant.conf

To login following 2 commands can be used:

sudo wpa_supplicant -i eth1 -D wext -c /etc/wpa_supplicant.conf -B

This starts a background daemon (-B) to take care of the security and authentication functions. -i specifies the interface to use, -D the wireless driver (wext - Linux Wireless Extensions). -c gives the path to the configuration file.

sudo dhclient eth1

Gets a new IP address for interface eth1.

When configured correctly, a sudo ifup eth1 should be enough. But I had no chance to test this.