Its a simple way to opening port 80 in oracle 10g.

#STEP 01
Log in as Oracle
Edit the Apache configuration file:
1. $ORACLE_HOME/Apache/Apache/httpd.conf
port 7777
Listen 7777
Listen 80  <- new line

2. Save and close the file.

#Step 02
Log in as root.
1. Run the following commands :
cd ORACLE_HOME/Apache/Apache/bin
chown root .apachectl
chmod 6750 .apachectl

2. Stop and start opmn :
# export DISPLAY=10.10.1.0.10:0.0
# opmnctl stopall
# opmnctl startall