<rewrite>
    <allowedServerVariables>
        <add name="REMOTE_ADDR" />
        <add name="REMOTE_HOST" />
    </allowedServerVariables>
    <globalRules>
        <rule name="Remote" patternSyntax="ECMAScript">
            <match url=".*" ignoreCase="false" />
            <conditions>
                <add input="{REMOTE_ADDR}" pattern="^10.1.1.[123]$" ignoreCase="false" />
                <add input="{HTTP_X_FORWARDED_FOR}" pattern="d+.d+.d+.d+$" ignoreCase="false" />
            </conditions>
            <serverVariables>
                <set name="REMOTE_ADDR" value="{C:0}" />
                <set name="REMOTE_HOST" value="{C:0}" />
            </serverVariables>
            <action type="None" />
        </rule>
    </globalRules>
</rewrite>

<add input="{REMOTE_ADDR}" pattern="^10.1.1.[123]$" ignoreCase="false" />

10.1.1.1 or 10.1.1.2 or 10.1.1.3

<system.webServer>
    <rewrite>
        <rules>
            <rule name="IP Restricted" patternSyntax="ECMAScript" stopProcessing="true">
                <match url=".*" ignoreCase="false" />
                <conditions>
                    <add input="{REMOTE_ADDR}" pattern="^(127.|10.20.74.|10.25.182.|10.64.105.10)" ignoreCase="false" negate="true" />
                </conditions>
                <action type="Rewrite" url="/403.html" appendQueryString="false" logRewrittenUrl="true" />
            </rule>
        </rules>
    </rewrite>
</system.webServer>