Date: Thu, 24 Sep 2009 09:21:21 -0400 From: Steve Bertrand <steve@ibctech.ca> To: "B. Cook" <bcook@poughkeepsieschools.org> Cc: freebsd-questions@freebsd.org Subject: Re: net.inet.ip.random_id possible ASA problems? Message-ID: <4ABB7251.4060004@ibctech.ca> In-Reply-To: <4ABB679D.7030604@poughkeepsieschools.org> References: <4ABB679D.7030604@poughkeepsieschools.org>
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This is a cryptographically signed message in MIME format. --------------ms060103070907000702050900 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit B. Cook wrote: [ big snip ] > So after 6 hours of cisco techs.. all they could come up with is a "... > possible duplex mis-match.. " > > *sigh* > > So dropping my pf rules (which contain scrub settings) made no > difference, I found the above URL which seeme to point to > net.inet.ip.random_id. > > I can not find any 'freebsd.org' documentation pertaining to it > regarding what it actually does. I do however find it scattered amongst > tons of 'FreeBSD hardening' docs.. > > Can anyone shed some light on what this does? IIRC, random_id allows initial TCP sequence numbers to be randomized. Some OS sequence TCP packets in an incremental fashion, thereby making it quite easy for an attacker using a TCP Idle Scan to hijack a session, and extremely easy while the box is under very light network load. https://www.kb.cert.org/vuls/id/498440 I've never seen this setting cause any detriment, but we only use Cisco routers, not ASA's. AFAIK, random_id is off by default. It would be rather handy if they would provide you with some of the ASA's config snips, and perhaps interface counts and logs. You may also want to capture a pcap on the 'problematic' box to see if you can find anything interesting: # tcpdump -n -i em0 -s 0 -w /home/steve/packet-cap.pcap Steve --------------ms060103070907000702050900 Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIII/zCC AtowggJDoAMCAQICEEs5xg/J3t77QWJ4SatV1HcwDQYJKoZIhvcNAQEFBQAwYjELMAkGA1UE BhMCWkExJTAjBgNVBAoTHFRoYXd0ZSBDb25zdWx0aW5nIChQdHkpIEx0ZC4xLDAqBgNVBAMT I1RoYXd0ZSBQZXJzb25hbCBGcmVlbWFpbCBJc3N1aW5nIENBMB4XDTA5MDUwNzIzMTYxMFoX DTEwMDUwNzIzMTYxMFowQjEfMB0GA1UEAxMWVGhhd3RlIEZyZWVtYWlsIE1lbWJlcjEfMB0G CSqGSIb3DQEJARYQc3RldmVAaWJjdGVjaC5jYTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCC AQoCggEBAJSTRAjP1RVa87/mnZn+PBTbENgyhhBJ4rWApmaNcthzRdk2DB/49KrXx3EQP60w Lj4KU0DFkiGNVj9BnVxRAx/WDXKxGC3uGGEG6gjyWv8KFMWMsH9mL7y7uNow1HueT6pZUf9o yY8Ewd+01QpGi7FfXOae7lGHhbEwnEJGwz08ytRfLmH0KtEzlZanZZhwDGX5s1kIHnyxdACh 3byXY6Z2bOrx0rcrQHCnHJppxddR60F7igjaMuBFstE51h9XTgXDNKJbglqTug5ghGihNuP6 VsBN7ue62y96UGIE22TvKEcAQ665vQGjHqZeSzZYy+hWNOa27pWFmhlqFjx0x8MCAwEAAaMt MCswGwYDVR0RBBQwEoEQc3RldmVAaWJjdGVjaC5jYTAMBgNVHRMBAf8EAjAAMA0GCSqGSIb3 DQEBBQUAA4GBAMOmjxjp2Xzk6ZHLwTgFDzVhm98RjRT3UXotKjNIR7SgwfWF5wkJrx4I+dXu ui5ztMEq4bTTRgJ344MqE6uZiZlg+tBIFHZGCJfKdzsX4QuV2jmw0sR5dMaYxG6tlDB0YUMv gTqzV7ZDpiusTMOZe9pP1PdxFhOcIJXtMQDj5LhuMIIC2jCCAkOgAwIBAgIQSznGD8ne3vtB YnhJq1XUdzANBgkqhkiG9w0BAQUFADBiMQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhhd3Rl IENvbnN1bHRpbmcgKFB0eSkgTHRkLjEsMCoGA1UEAxMjVGhhd3RlIFBlcnNvbmFsIEZyZWVt YWlsIElzc3VpbmcgQ0EwHhcNMDkwNTA3MjMxNjEwWhcNMTAwNTA3MjMxNjEwWjBCMR8wHQYD VQQDExZUaGF3dGUgRnJlZW1haWwgTWVtYmVyMR8wHQYJKoZIhvcNAQkBFhBzdGV2ZUBpYmN0 ZWNoLmNhMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAlJNECM/VFVrzv+admf48 FNsQ2DKGEEnitYCmZo1y2HNF2TYMH/j0qtfHcRA/rTAuPgpTQMWSIY1WP0GdXFEDH9YNcrEY Le4YYQbqCPJa/woUxYywf2YvvLu42jDUe55PqllR/2jJjwTB37TVCkaLsV9c5p7uUYeFsTCc QkbDPTzK1F8uYfQq0TOVlqdlmHAMZfmzWQgefLF0AKHdvJdjpnZs6vHStytAcKccmmnF11Hr QXuKCNoy4EWy0TnWH1dOBcM0oluCWpO6DmCEaKE24/pWwE3u57rbL3pQYgTbZO8oRwBDrrm9 AaMepl5LNljL6FY05rbulYWaGWoWPHTHwwIDAQABoy0wKzAbBgNVHREEFDASgRBzdGV2ZUBp YmN0ZWNoLmNhMAwGA1UdEwEB/wQCMAAwDQYJKoZIhvcNAQEFBQADgYEAw6aPGOnZfOTpkcvB OAUPNWGb3xGNFPdRei0qM0hHtKDB9YXnCQmvHgj51e66LnO0wSrhtNNGAnfjgyoTq5mJmWD6 0EgUdkYIl8p3OxfhC5XaObDSxHl0xpjEbq2UMHRhQy+BOrNXtkOmK6xMw5l72k/U93EWE5wg le0xAOPkuG4wggM/MIICqKADAgECAgENMA0GCSqGSIb3DQEBBQUAMIHRMQswCQYDVQQGEwJa QTEVMBMGA1UECBMMV2VzdGVybiBDYXBlMRIwEAYDVQQHEwlDYXBlIFRvd24xGjAYBgNVBAoT EVRoYXd0ZSBDb25zdWx0aW5nMSgwJgYDVQQLEx9DZXJ0aWZpY2F0aW9uIFNlcnZpY2VzIERp dmlzaW9uMSQwIgYDVQQDExtUaGF3dGUgUGVyc29uYWwgRnJlZW1haWwgQ0ExKzApBgkqhkiG 9w0BCQEWHHBlcnNvbmFsLWZyZWVtYWlsQHRoYXd0ZS5jb20wHhcNMDMwNzE3MDAwMDAwWhcN MTMwNzE2MjM1OTU5WjBiMQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhhd3RlIENvbnN1bHRp bmcgKFB0eSkgTHRkLjEsMCoGA1UEAxMjVGhhd3RlIFBlcnNvbmFsIEZyZWVtYWlsIElzc3Vp bmcgQ0EwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMSmPFVzVftOucqZWh5owHUEcJ3f 6f+jHuy9zfVb8hp2vX8MOmHyv1HOAdTlUAow1wJjWiyJFXCO3cnwK4Vaqj9xVsuvPAsH5/Ef kTYkKhPPK9Xzgnc9A74r/rsYPge/QIACZNenprufZdHFKlSFD0gEf6e20TxhBEAeZBlyYLf7 AgMBAAGjgZQwgZEwEgYDVR0TAQH/BAgwBgEB/wIBADBDBgNVHR8EPDA6MDigNqA0hjJodHRw Oi8vY3JsLnRoYXd0ZS5jb20vVGhhd3RlUGVyc29uYWxGcmVlbWFpbENBLmNybDALBgNVHQ8E BAMCAQYwKQYDVR0RBCIwIKQeMBwxGjAYBgNVBAMTEVByaXZhdGVMYWJlbDItMTM4MA0GCSqG SIb3DQEBBQUAA4GBAEiM0VCD6gsuzA2jZqxnD3+vrL7CF6FDlpSdf0whuPg2H6otnzYvwPQc UCCTcDz9reFhYsPZOhl+hLGZGwDFGguCdJ4lUJRix9sncVcljd2pnDmOjCBPZV+V2vf3h9bG CE6u9uo05RAaWzVNd+NWIXiC3CEZNd4ksdMdRv9dX2VPMYIDZDCCA2ACAQEwdjBiMQswCQYD VQQGEwJaQTElMCMGA1UEChMcVGhhd3RlIENvbnN1bHRpbmcgKFB0eSkgTHRkLjEsMCoGA1UE AxMjVGhhd3RlIFBlcnNvbmFsIEZyZWVtYWlsIElzc3VpbmcgQ0ECEEs5xg/J3t77QWJ4SatV 1HcwCQYFKw4DAhoFAKCCAcMwGAYJKoZIhvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0B CQUxDxcNMDkwOTI0MTMyMTIxWjAjBgkqhkiG9w0BCQQxFgQU3oo3/PPHmQTJMaXc0Jh74DLR UoMwUgYJKoZIhvcNAQkPMUUwQzAKBggqhkiG9w0DBzAOBggqhkiG9w0DAgICAIAwDQYIKoZI hvcNAwICAUAwBwYFKw4DAgcwDQYIKoZIhvcNAwICASgwgYUGCSsGAQQBgjcQBDF4MHYwYjEL MAkGA1UEBhMCWkExJTAjBgNVBAoTHFRoYXd0ZSBDb25zdWx0aW5nIChQdHkpIEx0ZC4xLDAq BgNVBAMTI1RoYXd0ZSBQZXJzb25hbCBGcmVlbWFpbCBJc3N1aW5nIENBAhBLOcYPyd7e+0Fi eEmrVdR3MIGHBgsqhkiG9w0BCRACCzF4oHYwYjELMAkGA1UEBhMCWkExJTAjBgNVBAoTHFRo YXd0ZSBDb25zdWx0aW5nIChQdHkpIEx0ZC4xLDAqBgNVBAMTI1RoYXd0ZSBQZXJzb25hbCBG cmVlbWFpbCBJc3N1aW5nIENBAhBLOcYPyd7e+0FieEmrVdR3MA0GCSqGSIb3DQEBAQUABIIB ADIZRvTIFaA1Tl2s8UXtEgwzsCYSfgGSOeFVUngtIcw2yvftLyQeqR52NfOZB4RIbbKVyvvR fXlcCwQcKd2qiuFFOe9X35bq1FPia32LgqNqDwsLp2vJNwScqAUZSomCZZvdY+Bqa53MVc04 p6dnfKnW3dO1/RiQLC6O7jkX+3wWJBhcj06KI7fNiHu+U4i2EeUjxpehmg39WjzeevwhV1BB vrWW8gt+eax+l+CnMdUfZbPY2vQ4tSAq0bSxRb1r3p7s6IvwoqPA6DHwRMmiR1QW7a6xQGfq hopMFKXTdvn4U26kQ53srCxDEH8eKI2MO3m+De55HHCTFCkO/XQ1WcUAAAAAAAA= --------------ms060103070907000702050900--
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