1. Specify the netrc file to libzz using the procedure in oc.h:

   oc_set_netrc(OClink* link, const char* file)
   

   (This is equivalent to the -N flag to ocprint).

2. Put the following line in your .daprc/.dodsrc file.

   HTTP.NETRC=<path to netrc file>
   

One final note. In using this, it is almost certain that you will need to specify a real cookie jar file (HTTP.COOKIEJAR) so that the redirect site can pass back authorization information.

URL Constrained RC File Entries

Examples.

[remotetest.unidata.ucar.edu]HTTP.VERBOSE=1
or
[fake.ucar.edu:9090]HTTP.VERBOSE=0

For example, the URL

http://remotetest.unidata.ucar.edu/thredds/dodsC/testdata/testData.nc

Similarly,

http://fake.ucar.edu:9090/dts/test.01

Client-Side Certificates

• HTTP.COOKIEJAR — a file path for storing cookies across re-direction.
• HTTP.NETRC — the path to the netrc file.
• HTTP.SSL.CERTIFICATE — the file path for the client side certificate file.
• HTTP.SSL.KEY — this should have the same value as HTTP.SSL.CERTIFICATE.
• HTTP.SSL.CAPATH — the path to a "certificates" directory.
• HTTP.SSL.VALIDATE — force validation of the server certificate.

Appendix A. All RC-File Keys

Appendix B. URS Access in Detail

Appendix C. ESG Access in Detail

In order to access ESG datasets, however, it is necessary to register as a user with ESG and to setup your environment so that proper authentication is established between an zz client program and the ESG data server. Specifically, it is necessary to use what is called "client-side keys" to enable this authentication. Normally, when a client accesses a server in a secure fashion (using "https"), the server provides an authentication certificate to the client. With client-side keys, the client must also provide a certificate to the server so that the server can know with whom it is communicating.

The zz library uses the curl library and it is that underlying library that must be properly configured.

Terminology

• Keystore - a repository to hold the client side key.
• Truststore - a repository to hold a chain of certificates that can be used to validate the certificate sent by the server to the client.

Initial Steps

1. Register at http://badc.nerc.ac.uk/register to obtain access to badc and to obtain an openid, which will looks something like:

   https://ceda.ac.uk/openid/Firstname.Lastname

2. Ask BADC for access to whatever datasets are of interest.

3. Obtain short term credentials at http://grid.ncsa.illinois.edu/myproxy/MyProxyLogon/ You will need to download and run the MyProxyLogon program. This will create a keyfile in, typically, the directory ".globus". The keyfile will have a name similar to this: "x509up_u13615" The other elements in ".globus" are certificates to use in validating the certificate your client gets from the server.

4. Obtain the program source ImportKey.java from this location: http://www.agentbob.info/agentbob/79-AB.html (read the whole page, it will help you understand the remaining steps).

Building the KeyStore

    openssl pkcs8 -topk8 -nocrypt -in x509up_u13615 -inform PEM -out key.der -outform DER

    openssl x509 -in x509up_u13615 -inform PEM -out cert.der -outform DER

    java -classpath  -Dkeypassword="" -Dkeystore=./ key.der cert.der

Building the TrustStore

  keytool -trustcacerts -storepass "password" -v -keystore "truststore"  -importcert -file "${c}"

Running the C Client

• HTTP.COOKIEJAR=~/.dods_cookies
• HTTP.NETRC=~/.netrc
• HTTP.SSL.CERTIFICATE=~/esgkeystore
• HTTP.SSL.KEY=~/esgkeystore
• HTTP.SSL.CAPATH=~/.globus
• HTTP.SSL.VALIDATE=1

As noted, also uses re-direction based authentication. So, when it receives an initial connection from a client, it redirects to a separate authentication server. When that server has authenticated the client, it redirects back to the original url to complete the request.

Script for creating Stores

#!/bin/sh -x
KEYSTORE="esgkeystore"
TRUSTSTORE="esgtruststore"
GLOBUS="globus"
TRUSTROOT="certificates"
CERT="x509up_u13615"
TRUSTROOTPATH="$GLOBUS/$TRUSTROOT"
CERTFILE="$GLOBUS/$CERT"
PWD="password"

D="-Dglobus=$GLOBUS"
CCP="bcprov-jdk16-145.jar" 
CP="./build:${CCP}" 
JAR="myproxy.jar"

# Initialize needed directories
rm -fr build
mkdir build
rm -fr $GLOBUS
mkdir $GLOBUS
rm -f $KEYSTORE
rm -f $TRUSTSTORE

# Compile MyProxyCmd and ImportKey
javac -d ./build -classpath "$CCP" *.java
javac -d ./build ImportKey.java

# Execute MyProxyCmd
java -cp "$CP myproxy.MyProxyCmd

# Build the keystore
openssl pkcs8 -topk8 -nocrypt -in $CERTFILE -inform PEM -out key.der -outform DER
openssl x509 -in $CERTFILE -inform PEM -out cert.der -outform DER
java -Dkeypassword=$PWD -Dkeystore=./${KEYSTORE} -cp ./build ImportKey key.der cert.der

# Clean up the certificates in the globus directory
for c in ${TRUSTROOTPATH}/*.0 ; do
    alias=`basename $c .0`
    sed -e '0,/---/d' <$c >/tmp/${alias}
    echo "-----BEGIN CERTIFICATE-----" >$c       
    cat /tmp/${alias} >>$c
done
 
# Build the truststore
for c in ${TRUSTROOTPATH}/*.0 ; do
    alias=`basename $c .0`
    echo "adding: $TRUSTROOTPATH/${c}"
    echo "alias: $alias"
    yes | keytool -trustcacerts -storepass "$PWD" -v -keystore ./$TRUSTSTORE -alias $alias -importcert -file "${c}"
done
exit