The bug report below, which I just submitted to the krb5 maintainers, applies to just about every Kerberos-authenticated application. Fixing the library as described below won't actually fix the applications; each application will have to be modified separately to add a configuration setting indicating whether it should allow remote address discrepancies. For all the apps. that use PAM, this could be done with a single new PAM setting. Date: Wed, 26 Jun 2002 07:28:20 -0400 From: Jonathan Kamens <jik.ma.us> To: krb5-bugs Subject: rb5_rd_priv can never never work through NAT In Kerberos 1.2.5 and previous versions: If I'm on a machine which accesses the Internet through a NAT firewall, such that when my requests get to their destinations their source address has been modified, and I attempt to use an application which uses krb5_{mk,rd}_priv to authenticate to a machine outside the firewall, it can't possibly work because of this code in krb5_rd_priv_basic() in lib/krb5/krb/rd_priv.c: if (!krb5_address_compare(context,remote_addr,privmsg_enc_part->s_address))\ { retval = KRB5KRB_AP_ERR_BADADDR; goto cleanup_data; } There needs to be a way for the caller to tell krb5_rd_priv(), and hence krb5_rd_priv_basic(), that it doesn't want it to check the remote address. It would make sense to do this in krb5_rd_priv_basic() simply by not executing the code above if remote_addr is null, and then the caller could obtain this behavior simply by not setting the remote address in the authentication context before calling krb5_rd_priv(). I realize that there are security implications in not checking the remote address, but it's sometimes an unavoidable situation. Besides, if you're using a NAT firewall, you've probably got other security precautions in place to offset the loss of this one :-). jik
Red Hat apologizes that these issues have not been resolved yet. We do want to make sure that no important bugs slip through the cracks. Red Hat Linux 7.3 and Red Hat Linux 9 are no longer supported by Red Hat, Inc. They are maintained by the Fedora Legacy project (http://www.fedoralegacy.org/) for security updates only. If this is a security issue, please reassign to the 'Fedora Legacy' product in bugzilla. Please note that Legacy security update support for these products will stop on December 31st, 2006. If this is not a security issue, please check if this issue is still present in a current Fedora Core release. If so, please change the product and version to match, and check the box indicating that the requested information has been provided. If you are currently still running Red Hat Linux 7.3 or 9, please note that Fedora Legacy security update support for these products will stop on December 31st, 2006. You are strongly advised to upgrade to a current Fedora Core release or Red Hat Enterprise Linux or comparable. Some information on which option may be right for you is available at http://www.redhat.com/rhel/migrate/redhatlinux/. Any bug still open against Red Hat Linux 7.3 or 9 at the end of 2006 will be closed 'CANTFIX'. Again, if this bug still exists in a current release, or is a security issue, please change the product as necessary. We thank you for your help, and apologize again that we haven't handled these issues to this point.
Red Hat Linux is no longer supported by Red Hat, Inc. If you are still running Red Hat Linux, you are strongly advised to upgrade to a current Fedora Core release or Red Hat Enterprise Linux or comparable. Some information on which option may be right for you is available at http://www.redhat.com/rhel/migrate/redhatlinux/. Closing as CANTFIX.