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justin at justinshore Mar 7, 2008, 11:55 AM Views: 2348 Permalink Customer-facing ACLs This question will probably get lost in the Friday afternoon lull but we'll give it a try anyway. What kind of customer-facing filtering do you do (ingress and egress)? This of course is dependent on the type of customer, so lets assume we're talking about an average residential customer. Do you block SYNs destined to your customers? Do you rate-limit SYNs destined for your customers? SYNs on privileged ports? Do you block any customer-facing egress traffic at all? What about ingress? SMTP, NetBIOS, MS-SQL, common proxy ports (3128, 6588)? What ICMP types do you allow or disallow? I'm assuming everyone uses uRPF at all their edges already so that eliminates the need for specific ACEs with ingress/egress network verification checks. Do you filter anything destined to your network infrastructure on your customer-facing edges? Does anyone filter traffic destined to the PE side of a PE-CE link from the outside world? For those of you with cable networks, what all do you block with the CM? We're considering blocking NetBIOS and DHCP server traffic (DHCP server packets are already blocked at the CMTS but this would keep that junk off our infrastructure). For SMTP we permit access to our SMTP servers on tcp/25 to all our broadband users. We also permit our customers with static IPs (residential and business) to send SMTP without restrictions. After those permits we explicitly block tcp/25. This has worked fairly well for us. It sure makes it easy to find infected PCs with spambots. We don't touch tcp/587. For ICMP we permit echo, replies, packet-too-big, and time-exceeded. Everything else gets dropped. Frags are explicitly dropped before any permits. We also block common proxy ports to and from the customers (the to includes ports not always used for proxies). This has been very effective in catching a number of bots that scanned for open Squid proxies or script kiddie junk that used WinGate with the default settings. Is there a BCP for customer-facing ACLs? Justin

Subject User Time Customer-facing ACLs justin at justinshore Mar 7, 2008, 11:55 AM     Re: Customer-facing ACLs streiner at cluebyfour Mar 7, 2008, 12:08 PM     Re: Customer-facing ACLs Valdis.Kletnieks at vt Mar 7, 2008, 12:12 PM         Re: Customer-facing ACLs justin at justinshore Mar 7, 2008, 12:19 PM             RE: Customer-facing ACLs tims at donet Mar 7, 2008, 12:48 PM         Re: Customer-facing ACLs dan at beanfield Mar 7, 2008, 12:21 PM     Re: Customer-facing ACLs rbeverly at rbeverly Mar 7, 2008, 12:35 PM     Re: Customer-facing ACLs kgasso-lists at visp Mar 7, 2008, 12:43 PM         RE: Customer-facing ACLs frnkblk at iname Mar 7, 2008, 2:17 PM     Re: Customer-facing ACLs danny at tcb Mar 7, 2008, 12:55 PM     Re: Customer-facing ACLs surfer at mauigateway Mar 7, 2008, 1:22 PM         Re: Customer-facing ACLs justin at justinshore Mar 7, 2008, 2:54 PM             Re: Customer-facing ACLs dave.nanog at alfordmedia Mar 7, 2008, 3:39 PM                 Re: Customer-facing ACLs joelja at bogus Mar 7, 2008, 8:12 PM     Re: Customer-facing ACLs surfer at mauigateway Mar 7, 2008, 3:57 PM         RE: Customer-facing ACLs Jason.Carpenter at citadelgroup Mar 7, 2008, 4:15 PM         Re: Customer-facing ACLs dave.nanog at alfordmedia Mar 7, 2008, 4:49 PM             Re: Customer-facing ACLs andy at xecu Mar 7, 2008, 6:54 PM                 Re: Customer-facing ACLs dave.nanog at alfordmedia Mar 7, 2008, 7:38 PM                     Re: Customer-facing ACLs blakjak at blakjak Mar 7, 2008, 8:02 PM             Re: Customer-facing ACLs cmarlatt at rxsec Mar 10, 2008, 7:10 AM                 Re: Customer-facing ACLs adrian at creative Mar 10, 2008, 7:53 AM                     Re: Customer-facing ACLs justin at justinshore Mar 10, 2008, 8:23 AM         Re: Customer-facing ACLs sean at donelan Mar 10, 2008, 9:57 AM         Re: Customer-facing ACLs andy at nosignal Mar 18, 2008, 12:58 PM             Re: Customer-facing ACLs tme at multicasttech Mar 18, 2008, 1:27 PM     RE: Customer-facing ACLs surfer at mauigateway Mar 7, 2008, 5:21 PM         Re: Customer-facing ACLs justin at justinshore Mar 7, 2008, 6:44 PM             Re: Customer-facing ACLs adrian at creative Mar 7, 2008, 7:26 PM     RE: Customer-facing ACLs fergdawg at netzero Mar 7, 2008, 6:22 PM     RE: Customer-facing ACLs frnkblk at iname Mar 7, 2008, 9:29 PM     Re: Customer-facing ACLs joelja at bogus Mar 7, 2008, 9:40 PM         RE: Customer-facing ACLs frnkblk at iname Mar 8, 2008, 10:10 AM     Re: Customer-facing ACLs dave.nanog at alfordmedia Mar 7, 2008, 10:59 PM         Re: Customer-facing ACLs blakjak at blakjak Mar 7, 2008, 11:44 PM     Re: Customer-facing ACLs dave.nanog at alfordmedia Mar 8, 2008, 12:10 AM         Re: Customer-facing ACLs jay at west Mar 8, 2008, 12:58 PM             Re: Customer-facing ACLs bill.norton at gmail Mar 8, 2008, 2:40 PM         Re: Customer-facing ACLs justin at justinshore Mar 9, 2008, 3:56 PM     Re: Customer-facing ACLs adrian at creative Mar 8, 2008, 12:28 AM     Re: Customer-facing ACLs justin at justinshore Mar 8, 2008, 10:17 AM     Re: Customer-facing ACLs justin at justinshore Mar 8, 2008, 10:27 AM         RE: Customer-facing ACLs frnkblk at iname Mar 8, 2008, 11:54 AM     Re: Customer-facing ACLs mtinka at globaltransit Mar 8, 2008, 7:24 PM     Re: Customer-facing ACLs surfer at mauigateway Mar 10, 2008, 11:53 AM         Re: Customer-facing ACLs sean at donelan Mar 10, 2008, 12:30 PM     Re: Customer-facing ACLs surfer at mauigateway Mar 10, 2008, 1:05 PM         Re: Customer-facing ACLs sean at donelan Mar 10, 2008, 6:52 PM     Customer-facing ACLs mailinglist at bangky Mar 10, 2008, 4:58 PM         Re: Customer-facing ACLs andy at xecu Mar 10, 2008, 5:12 PM             Re: Customer-facing ACLs mailinglist at bangky Mar 10, 2008, 5:40 PM                 RE: Customer-facing ACLs frnkblk at iname Mar 10, 2008, 10:15 PM         Re: Customer-facing ACLs morrowc.lists at gmail Mar 10, 2008, 7:33 PM         Re: Customer-facing ACLs justin at justinshore Mar 10, 2008, 9:04 PM     Customer-facing ACLs mack at exchange Mar 10, 2008, 5:49 PM     Re: Customer-facing ACLs adrian at creative Mar 10, 2008, 9:18 PM     RE: Customer-facing ACLs frnkblk at iname Mar 10, 2008, 10:10 PM     Re: Customer-facing ACLs lists05 at equinephotoart Mar 10, 2008, 11:25 PM     Re: Customer-facing ACLs jrhett at netconsonance Mar 10, 2008, 11:27 PM         Re: Customer-facing ACLs christopher.morrow at gmail Mar 11, 2008, 11:41 AM     Re: Customer-facing ACLs surfer at mauigateway Mar 11, 2008, 6:58 PM     Re: Customer-facing ACLs surfer at mauigateway Mar 11, 2008, 7:23 PM     RE: Customer-facing ACLs surfer at mauigateway Mar 11, 2008, 7:34 PM         RE: Customer-facing ACLs sean at donelan Mar 11, 2008, 7:57 PM         RE: Customer-facing ACLs frnkblk at iname Mar 11, 2008, 7:57 PM     RE: Customer-facing ACLs surfer at mauigateway Mar 12, 2008, 4:39 PM         RE: Customer-facing ACLs frnkblk at iname Mar 12, 2008, 7:22 PM     Re: Customer-facing ACLs jlewis at lewis Mar 18, 2008, 8:47 PM         Re: Customer-facing ACLs adrian at creative Mar 18, 2008, 9:46 PM

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