プライベートロケーションでのKerberos（SPNEGO）認証のサポート

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sudo dnf install -y krb5-server krb5-workstation

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sudo tee /etc/krb5.conf > /dev/null <<'EOF'
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[libdefaults]
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    default_realm = <REALM_NAME>
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    dns_lookup_realm = false
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    dns_lookup_kdc = false
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    rdns = false
$

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[realms]
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    <REALM_NAME> = {
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        kdc = <EC2_PRIVATE_IP>
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        admin_server = <EC2_PRIVATE_IP>
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    }
$

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[domain_realm]
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    <EC2_INTERNAL_HOSTNAME> = <REALM_NAME>
$
EOF

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sudo tee /var/kerberos/krb5kdc/kdc.conf > /dev/null <<'EOF'
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[kdcdefaults]
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    kdc_ports = 88
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    kdc_tcp_ports = 88
$

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[realms]
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    <REALM_NAME> = {
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        acl_file = /var/kerberos/krb5kdc/kadm5.acl
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        dict_file = /usr/share/dict/words
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        admin_keytab = /var/kerberos/krb5kdc/kadm5.keytab
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        supported_enctypes = aes256-cts-hmac-sha1-96:normal aes128-cts-hmac-sha1-96:normal
$
    }
$
EOF

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# Create the Kerberos database (assign a master password when prompted)
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sudo kdb5_util create -r <REALM_NAME> -s
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# Grant admin permissions and enable KDC services on system boot
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echo "*/admin@<REALM_NAME> *" | sudo tee /var/kerberos/krb5kdc/kadm5.acl
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sudo systemctl enable --now krb5kdc kadmin

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mkdir -p /home/ec2-user/kerb-test
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# 1. Create client principal & keytab for synthetics runners
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sudo kadmin.local -q "addprinc -randkey <CLIENT_PRINCIPAL>@<REALM_NAME>"
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sudo kadmin.local -q "ktadd -k <CLIENT_KEYTAB_PATH> <CLIENT_PRINCIPAL>@<REALM_NAME>"
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sudo chmod 644 <CLIENT_KEYTAB_PATH>
$

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# 2. Create HTTP service principal name (SPN) keytab for the web server
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sudo kadmin.local -q "addprinc -randkey HTTP/<EC2_INTERNAL_HOSTNAME>@<REALM_NAME>"
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sudo kadmin.local -q "ktadd -k /home/ec2-user/kerb-test/http.keytab HTTP/<EC2_INTERNAL_HOSTNAME>@<REALM_NAME>"
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sudo chmod 644 /home/ec2-user/kerb-test/http.keytab

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mkdir -p ~/kerb-test/httpd-image && cd ~/kerb-test/httpd-image
$

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cat > kerb-test.conf <<'EOF'
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<Location /kerb-test>
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    AuthType GSSAPI
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    AuthName "Kerberos Login"
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    GssapiCredStore keytab:/etc/krb5-http.keytab
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    Require valid-user
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</Location>
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EOF
$

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cat > Dockerfile <<'EOF'
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FROM debian:bookworm-slim
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RUN apt-get update && \
>
    apt-get install -y --no-install-recommends apache2 libapache2-mod-auth-gssapi krb5-user && \
>
    a2enmod auth_gssapi && \
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    mkdir -p /var/www/html/kerb-test && \
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    echo '<h1>Kerberos SSO worked</h1>' > /var/www/html/kerb-test/index.html && \
>
    rm -rf /var/lib/apt/lists/*
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COPY kerb-test.conf /etc/apache2/conf-enabled/kerb-test.conf
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EXPOSE 80
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CMD ["apache2ctl", "-D", "FOREGROUND"]
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EOF
$

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docker build -t kerb-test-httpd .
$

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docker run -d --name kerb-test-httpd \
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  -p 8080:80 \
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  -v /etc/krb5.conf:/etc/krb5.conf:ro \
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  -v /home/ec2-user/kerb-test/http.keytab:/etc/krb5-http.keytab:ro \
>
  kerb-test-httpd

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# 1. Map internal hostname in /etc/hosts
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echo "<EC2_PRIVATE_IP> <EC2_INTERNAL_HOSTNAME>" | sudo tee -a /etc/hosts
$

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# 2. Verify unauthenticated challenge returns 401 Unauthorized
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curl -i http://<EC2_INTERNAL_HOSTNAME>:8080/kerb-test/
$

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# 3. Test ticket acquisition and end-to-end Kerberos SSO
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kinit -kt <CLIENT_KEYTAB_PATH> <CLIENT_PRINCIPAL>@<REALM_NAME>
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curl --negotiate -u : -i http://<EC2_INTERNAL_HOSTNAME>:8080/kerb-test/