After configuring nginx and apache, the file index.php has to be placed in the document root directory (/var/www/html). This PHP file outputs the value of the variable $_SERVER['REMOTE_ADDR'] which should always carry the client's real IP address and should always contain trustworthy values when being processed by a webserver.
In order to keep this simple, the following IPv4 addresses will be used: Server IP: 192.168.1.1 Client IP: 192.168.2.2 Now our client wants to access our site by using the following command: curl http://192.168.1.1/index.php Output: 192.168.2.2 (As expected, the real IP address of the requesting client) Let's assume the client accesses a SEO friendly URL and should be internally redirected to the file index.php. To test this, the following curl command can be used: curl http://192.168.1.1/seo-friendly-url/ Output: 192.168.2.2 (As expected) So far so good. Let's assume our client provides the header X-Forwarded- For with an arbitrary IP address: curl http://192.168.1.1/seo-friendly-url/ -H "X-Forwarded-For: 1.1.1.1" Output: 1.1.1.1 (Unexpected; should contain the real IP address instead of the Header value) I hope the supplied configuration files and this short explanation can be of help. I am happy to provide additional information if needed. ** Also affects: apache2 (Debian) Importance: Undecided Status: New -- You received this bug notification because you are a member of नेपाली भाषा समायोजकहरुको समूह, which is subscribed to Xenial. Matching subscriptions: Ubuntu 16.04 Bugs https://bugs.launchpad.net/bugs/1875299 Title: Apache's mod_remoteip: IP address spoofing via X-Forwarded-For when mod_rewrite rule is triggered Status in apache2 package in Ubuntu: Confirmed Status in apache2 source package in Xenial: Triaged Status in apache2 package in Debian: New Bug description: There is a bug in mod_remoteip (a part of Apache Web Server): https://bz.apache.org/bugzilla/show_bug.cgi?id=60251 Although the status of this bug is "NEW", actually it was fixed in Apache 2.4.24. Although a CVE id was not requested yet, actually it is a vulnerability. The fix was not backported to Ubuntu 16.04 (xenial). Impact: if a victim uses Apache rewrite rules, then an attacker can spoof his IP address for logs and PHP scripts. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: apache2 2.4.18-2ubuntu3.14 ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8 Uname: Linux 4.4.0-22-generic x86_64 Apache2ConfdDirListing: False ApportVersion: 2.20.1-0ubuntu2.23 Architecture: amd64 Date: Mon Apr 27 13:17:43 2020 SourcePackage: apache2 UpgradeStatus: No upgrade log present (probably fresh install) error.log: modified.conffile..etc.apache2.apache2.conf: [modified] modified.conffile..etc.apache2.mods-available.dir.conf: [modified] modified.conffile..etc.apache2.mods-available.ssl.conf: [modified] modified.conffile..etc.apache2.ports.conf: [modified] modified.conffile..etc.apache2.sites-available.000-default.conf: [modified] modified.conffile..etc.apache2.sites-available.default-ssl.conf: [modified] mtime.conffile..etc.apache2.apache2.conf: 2020-04-23T15:45:48.416970 mtime.conffile..etc.apache2.mods-available.dir.conf: 2020-04-23T12:03:13.711062 mtime.conffile..etc.apache2.mods-available.ssl.conf: 2020-04-23T12:02:44.854484 mtime.conffile..etc.apache2.ports.conf: 2020-04-23T15:45:48.169037 mtime.conffile..etc.apache2.sites-available.000-default.conf: 2020-04-23T15:45:48.197030 mtime.conffile..etc.apache2.sites-available.default-ssl.conf: 2020-04-23T15:45:48.225022 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apache2/+bug/1875299/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~group.of.nepali.translators Post to : [email protected] Unsubscribe : https://launchpad.net/~group.of.nepali.translators More help : https://help.launchpad.net/ListHelp
