I don't run Mandriva so I can't really tell you what exactly is going on. BUT ......
Being the user of shorewall myself, I might point you to the right direction.
Shorewall's policy file is used for universal config. The "rules" file is what comes before policy file. Even if your stop your firewall, you need to flush all the iptables rules to accept the connections.
Example rules are here for your reference. This box is my gateway.
#SOURCE DEST POLICY LOG LEVEL LIMIT:BURST
loc net ACCEPT
# If you want open access to the Internet from your Firewall
# remove the comment from the following line.
#fw net ACCEPT
net all DROP info
# THE FOLLOWING POLICY MUST BE LAST
all all REJECT info
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
So what you do is if you want, say, web connections, then replace port 22 with port 80, restart shorewall (which will reflush all your rules) and you should be good to go. Let us know how it went.
ACTION SOURCE DEST PROTO DEST SOURCE ORIGINAL# PORT PORT(S) DEST
# Accept DNS connections from the firewall to the network
#ACCEPT fw net tcp 53
#ACCEPT fw net udp 53
# Accept SSH connections from the local network for administration
ACCEPT loc fw tcp 22
# Allow Ping To And From Firewall
ACCEPT loc fw icmp 8
ACCEPT net fw icmp 8
ACCEPT fw loc icmp 8
ACCEPT fw net icmp 8
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE