Getting bad interpreter error

> #!/bin/sh
> #
> # rc.firewall-2.4
> FWVER=0.70
> #
> #               Initial SIMPLE IP Masquerade test for 2.4.x kernels
> #               using IPTABLES.  
> #
> #               Once IP Masquerading has been tested, with this simple 
> #               ruleset, it is highly recommended to use a stronger 
> #               IPTABLES ruleset either given later in this HOWTO or 
> #               from another reputable resource.
> #
> #
> #
> # Log:
> #       0.70 - Added commented option for IRC nat module
> #            - Added additional use of environment variables 
> #            - Added additional formatting
> #       0.63 - Added support for the IRC IPTABLES module
> #       0.62 - Fixed a typo on the MASQ enable line that used eth0
> #              instead of $EXTIF
> #       0.61 - Changed the firewall to use variables for the internal
> #              and external interfaces.
> #       0.60 - 0.50 had a mistake where the ruleset had a rule to DROP
> #              all forwarded packets but it didn't have a rule to ACCEPT
> #              any packets to be forwarded either
> #            - Load the ip_nat_ftp and ip_conntrack_ftp modules by default
> #       0.50 - Initial draft
> #

> #Setting the EXTERNAL and INTERNAL interfaces for the network
> #
> #  Each IP Masquerade network needs to have at least one
> #  external and one internal network.  The external network
> #  is where the natting will occur and the internal network
> #  should preferably be addressed with a RFC1918 private address
> #  scheme.
> #
> #  For this example, "eth0" is external and "eth1" is internal"
> #
> #  NOTE:  If this doesnt EXACTLY fit your configuration, you must 
> #         change the EXTIF or INTIF variables above. For example: 
> #
> #               EXTIF="ppp0" 
> #
> #            if you are a modem user.
> #
> EXTIF="eth0"
> INTIF="eth1"
> echo "   External Interface:  $EXTIF"
> echo "   Internal Interface:  $INTIF"

> # With the new IPTABLES code, the core MASQ functionality is now either
> # modular or compiled into the kernel.  This HOWTO shows ALL IPTABLES
> # options as MODULES.  If your kernel is compiled correctly, there is
> # NO need to load the kernel modules manually.  
> #
> #  NOTE: The following items are listed ONLY for informational reasons.
> #        There is no reason to manual load these modules unless your
> #        kernel is either mis-configured or you intentionally disabled
> #        the kernel module autoloader.
> #

> # Upon the commands of starting up IP Masq on the server, the
> # following kernel modules will be automatically loaded:
> #
> # NOTE:  Only load the IP MASQ modules you need.  All current IP MASQ 
> #        modules are shown below but are commented out from loading.
> # ===============================================================

> #Load the stateful connection tracking framework - "ip_conntrack"
> #
> # The conntrack  module in itself does nothing without other specific 
> # conntrack modules being loaded afterwards such as the "ip_conntrack_ftp"
> # module
> #
> #  - This module is loaded automatically when MASQ functionality is 
> #    enabled 
> #
> #  - Loaded manually to clean up kernel auto-loading timing issues
> #
> echo -en "ip_conntrack, "
> $INSMOD ip_conntrack

> # Just to be complete, here is a list of the remaining kernel modules 
> # and their function.  Please note that several modules should be only
> # loaded by the correct master kernel module for proper operation.
> # --------------------------------------------------------------------
> #
> #    ipt_mark       - this target marks a given packet for future action.
> #                     This automatically loads the ipt_MARK module
> #
> #    ipt_tcpmss     - this target allows to manipulate the TCP MSS
> #                     option for braindead remote firewalls.
> #                     This automatically loads the ipt_TCPMSS module
> #
> #    ipt_limit      - this target allows for packets to be limited to
> #                     to many hits per sec/min/hr
> #
> #    ipt_multiport  - this match allows for targets within a range
> #                     of port numbers vs. listing each port individually
> #
> #    ipt_state      - this match allows to catch packets with various
> #                     IP and TCP flags set/unset
> #
> #    ipt_unclean    - this match allows to catch packets that have invalid
> #                     IP/TCP flags set
> #
> #    iptable_filter - this module allows for packets to be DROPped, 
> #                     REJECTed, or LOGged.  This module automatically 
> #                     loads the following modules:
> #
> #                     ipt_LOG - this target allows for packets to be 
> #                               logged
> #
> #                     ipt_REJECT - this target DROPs the packet and returns 
> #                                  a configurable ICMP packet back to the 
> #                                  sender.
> # 
> #    iptable_mangle - this target allows for packets to be manipulated
> #                     for things like the TCPMSS option, etc.

> #CRITICAL:  Enable IP forwarding since it is disabled by default since
> #
> #           Redhat Users:  you may try changing the options in
> #                          /etc/sysconfig/network from:
> #
> #                       FORWARD_IPV4=false
> #                             to
> #                       FORWARD_IPV4=true
> #
> echo "   enabling forwarding.."
> echo "1" > /proc/sys/net/ipv4/ip_forward

> # Enable simple IP forwarding and Masquerading
> #
> #  NOTE:  In IPTABLES speak, IP Masquerading is a form of SourceNAT or SNAT.
> #
> #  NOTE #2:  The following is an example for an internal LAN address in the
> #            192.168.0.x network with a 255.255.255.0 or a "24" bit subnet mask
> #            connecting to the Internet on external interface "eth0".  This
> #            example will MASQ internal traffic out to the Internet but not
> #            allow non-initiated traffic into your internal network.
> #
> #            
> #         ** Please change the above network numbers, subnet mask, and your 
> #         *** Internet connection interface name to match your setup
> #         

> #Clearing any previous configuration
> #
> #  Unless specified, the defaults for INPUT and OUTPUT is ACCEPT
> #    The default for FORWARD is DROP
> #
> echo "   clearing any existing rules and setting default policy.."
> $IPTABLES -P INPUT ACCEPT
> $IPTABLES -F INPUT 
> $IPTABLES -P OUTPUT ACCEPT
> $IPTABLES -F OUTPUT 
> $IPTABLES -P FORWARD DROP
> $IPTABLES -F FORWARD 
> $IPTABLES -t nat -F