Io Exception: Got minus one from a read call for TOAD connections

Solution:
1. Go to directory $TNS_ADMIN
2. Modify sqlnet.ora file with following parameter:
tcp.validnode_checking = no
Note: If you don't want to disable this, you can put the machine names as follows:
tcp.invited_nodes=(machine1, machine2)
3. Bounce listener

Ref:342332.1-Troubleshooting Login Problems in Oracle Applications 11i