In another post I commented that I had trouble yesterday with what seems to be Comcast blocking ports 21 and 80 so I couldn't serve ftp or http. I mentioned this to my brother who said he remembers reading somewhere that Comcast is "going after people running NAT" but he didn't remember any more. Has anyone else heard this? How would NAT be detected with SuSEfirewall2 on 9.0? Damon Register
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I've also heard that comcast was going after people setting up servers in the non-pro accounts. It seems that they only look at the default ports tho. So if you serve web from a non-standard port, you should be fine. About NAT, I seriously doubt they're doing anything about it (I know of examples of people using NAT -- which is as I understand what the linksys routers use -- for two years now, with no problems). Some dynamic dns servers will automatically forward web requests to the port you specify (look at the webhop service, by dyndns.org), i.e., people will type www.yourhost.com and get automatically say www.yourhost.com:12345. Adalberto On Monday 26 January 2004 11:27, Damon Register wrote:
In another post I commented that I had trouble yesterday with what seems to be Comcast blocking ports 21 and 80 so I couldn't serve ftp or http. I mentioned this to my brother who said he remembers reading somewhere that Comcast is "going after people running NAT" but he didn't remember any more. Has anyone else heard this? How would NAT be detected with SuSEfirewall2 on 9.0?
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I've also heard that comcast was going after people setting up servers in
On Monday 26 January 2004 1:08 pm, Adalberto Castelo wrote: the
non-pro accounts.
About NAT, I seriously doubt they're doing anything about it (I know of examples of
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice? people
using NAT -- which is as I understand what the linksys routers use -- for two years now, with no problems).
I have a Comcast account and a Linksys router, so I guess I'm implicitly using NAT. I've gotten the impression that Comcast is actually pretty tolerant of routers -- I seem to recall conversations with Comcast techies where I mentioned I had one and they seemed not to care. Paul Abrahams
-----Original Message----- From: "Paul W. Abrahams" <abrahams@acm.org> To: suse-linux-e@suse.com Date: Fri, 30 Jan 2004 22:27:41 -0500 Subject: Re: [SLE] Comcast and NAT
On Monday 26 January 2004 1:08 pm, Adalberto Castelo wrote:
I've also heard that comcast was going after people setting up servers in the non-pro accounts.
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice?
About NAT, I seriously doubt they're doing anything about it (I know of examples of people using NAT -- which is as I understand what the linksys routers use -- for two years now, with no problems).
I have a Comcast account and a Linksys router, so I guess I'm implicitly using NAT. I've gotten the impression that Comcast is actually pretty tolerant of routers -- I seem to recall conversations with Comcast techies where I mentioned I had one and they seemed not to care.
Paul Abrahams
In todays business section there was an article that Comcast was starting to crack down on the amount of bandwidth people were using, such as threating to subspend or cancel their accounts. Ken
Ken Schneider wrote:
In todays business section there was an article that Comcast was starting to crack down on the amount of bandwidth people were using, such as threating to subspend or cancel their accounts.
NAT does not necessarily mean more bandwidth. For example, I've got 4 computers behind my firewall, but normally use only one at a time and my dog and cat don't use the internet much. ;-)
* Paul W. Abrahams <abrahams@acm.org> [01-30-04 22:29]:
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice?
I have one and do not have a static IP. no-ip.org dydns,com is two ways that come immediately to mind and I am sure that there are others. I run a mail server and a web server... -- Patrick Shanahan Registered Linux User #207535 http://wahoo.no-ip.org @ http://counter.li.org
Paul W. Abrahams wrote:
On Monday 26 January 2004 1:08 pm, Adalberto Castelo wrote:
I've also heard that comcast was going after people setting up servers in
the
non-pro accounts.
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice?
While I have dhcp, the assigned address stays the same for so long, it might as well be static. Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
On Friday 30 January 2004 19:25, James Knott wrote:
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice?
While I have dhcp, the assigned address stays the same for so long, it might as well be static. Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
Say what? Maybe in your own (windows) network but not from outside. You need something like www.dyndns.org for reliable access on a dynamic ip. Host name means didly-squat. -- _____________________________________ John Andersen
John Andersen wrote:
On Friday 30 January 2004 19:25, James Knott wrote:
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice?
While I have dhcp, the assigned address stays the same for so long, it might as well be static. Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
Say what?
Maybe in your own (windows) network but not from outside.
You need something like www.dyndns.org for reliable access on a dynamic ip. Host name means didly-squat.
I mean exactly what I said. My host name is derived from my mac address. I can do a host lookup from elsewhere and find my home IP. I rely on this for my vpn from my notebook to my home network. In the configuration for the vpn on the notebook end, I specify my host name as assigned by Rogers. I can even use the host command on another ISP, which returns my IP address. So, as I said, even though my IP may be dhcp, the host name is static and can be used to reach my home system. The hostname follows the form of "CPE<computer mac>-CM<modem mac>.cpe.net.cable.rogers.com". Since neither the computer nor cable modem macs change, the host name is permanent.
On Saturday 31 January 2004 11:20, James Knott wrote:
John Andersen wrote:
On Friday 30 January 2004 19:25, James Knott wrote:
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice?
While I have dhcp, the assigned address stays the same for so long, it might as well be static. Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
Say what?
Maybe in your own (windows) network but not from outside.
You need something like www.dyndns.org for reliable access on a dynamic ip. Host name means didly-squat.
I mean exactly what I said. My host name is derived from my mac address. I can do a host lookup from elsewhere and find my home IP. I rely on this for my vpn from my notebook to my home network. In the configuration for the vpn on the notebook end, I specify my host name as assigned by Rogers. I can even use the host command on another ISP, which returns my IP address. So, as I said, even though my IP may be dhcp, the host name is static and can be used to reach my home system. The hostname follows the form of "CPE<computer mac>-CM<modem mac>.cpe.net.cable.rogers.com". Since neither the computer nor cable modem macs change, the host name is permanent.
I see what you mean now. dig CPE00055dfefce4-CM014150004408.cpe.net.cable.rogers.com yields your IP... But still, why would you want to carry around that big mess when you could go to dyndns.org and get a nice short name? -- _____________________________________ John Andersen
John Andersen wrote:
I see what you mean now. dig CPE00055dfefce4-CM014150004408.cpe.net.cable.rogers.com yields your IP... But still, why would you want to carry around that big mess when you could go to dyndns.org and get a nice short name?
I don't type that every time I want to use it. I have the full host name configured into my vpn, which means I don't have to enter it every time. I also have it in my /etc/hosts file, along with the short host name "home". This means that if I want to ssh to my home network, I'd enter "ssh home". Should the IP change, that would fail and I'd have to do a new lookup, to update my hosts file. And if I absolutely need it on another computer, I have the info stored in my Palm computer. ;-)
On Saturday 31 January 2004 3:20 pm, James Knott wrote:
[My] hostname follows the form of "CPE<computer mac>-CM<modem mac>.cpe.net.cable.rogers.com". Since neither the computer nor cable modem macs change, the host name is permanent.
As I noted in a previous post, my hostname has a different form, though still related to my MAC address: You: "CPE<computer mac>-CM<modem mac>.cpe.net.cable.rogers.com Me: h<modem MAC>.ne.client2.attbi.com. Is that because I'm on Comcast and you're on Rogersnet (or whatever your ISP is called)? Paul Abrahams
-----Original Message----- From: "Paul W. Abrahams" <abrahams@acm.org>
[My] hostname follows the form of "CPE<computer mac>-CM<modem mac>.cpe.net.cable.rogers.com". Since neither the computer nor cable modem macs change, the host name is permanent.
As I noted in a previous post, my hostname has a different form, though still related to my MAC address:
You: "CPE<computer mac>-CM<modem mac>.cpe.net.cable.rogers.com Me: h<modem MAC>.ne.client2.attbi.com.
Is that because I'm on Comcast and you're on Rogersnet (or whatever your ISP is called)?
Yes this is because you are with Comcast. They have your MAC address to track your usage and incorporate it into a -hostname- they assign to you. I know of no other ISP that does this. It is not a hostname from your MAC address only used there by Comcast. Ken
Ken Schneider wrote:
-----Original Message----- From: "Paul W. Abrahams" <abrahams@acm.org>
[My] hostname follows the form of "CPE<computer mac>-CM<modem mac>.cpe.net.cable.rogers.com". Since neither the computer nor cable modem macs change, the host name is permanent.
As I noted in a previous post, my hostname has a different form, though still related to my MAC address:
You: "CPE<computer mac>-CM<modem mac>.cpe.net.cable.rogers.com Me: h<modem MAC>.ne.client2.attbi.com.
Is that because I'm on Comcast and you're on Rogersnet (or whatever your ISP is called)?
Yes this is because you are with Comcast. They have your MAC address to track your usage and incorporate it into a -hostname- they assign to you. I know of no other ISP that does this.
Well, as I mentioned earlier, Rogers also does that.
It is not a hostname from your MAC address only used there by Comcast.
Ken
On Saturday 31 January 2004 4:43 am, John Andersen wrote:
On Friday 30 January 2004 19:25, James Knott wrote:
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice?
While I have dhcp, the assigned address stays the same for so long, it might as well be static. Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
Say what?
Maybe in your own (windows) network but not from outside.
There seems to be a major misunderstanding here. As a general rule, there is no relationship between a hostname and the MAC address of the ethernet card on the computer having that hostname. However, Comcast has created an exception to that rule because they (AT&T Broadband, actually) know the MAC address of each computer on their net and assign to that computer a hostname derived from that MAC address. In particular, James, knowing the MAC address of his computer and being a Comcast customer, can address his computer by a fixed hostname, namely, the one derived from that MAC address. Paul Abrahams
Paul W. Abrahams wrote:
On Saturday 31 January 2004 4:43 am, John Andersen wrote:
On Friday 30 January 2004 19:25, James Knott wrote:
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice?
While I have dhcp, the assigned address stays the same for so long, it might as well be static. Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
Say what?
Maybe in your own (windows) network but not from outside.
There seems to be a major misunderstanding here. As a general rule, there is no relationship between a hostname and the MAC address of the ethernet card on the computer having that hostname. However, Comcast has created an exception to that rule because they (AT&T Broadband, actually) know the MAC address of each computer on their net and assign to that computer a hostname derived from that MAC address. In particular, James, knowing the MAC address of his computer and being a Comcast customer, can address his computer by a fixed hostname, namely, the one derived from that MAC address.
Actually, I'm on Rogers. The other guy with the mac in the host name is on Comcast. Rogers creates the host name out of both the computer and cable modem mac addresses.
On Friday 30 January 2004 11:25 pm, James Knott wrote:
While my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
I remember knowing that I did have a fixed hostname related to my MAC address, but I don't remember how to figure out what it is. Comcast is very reluctant to provide technical information about anything other than the standard vanilla Windows connection. They won't even tell you what their nameservers are -- you have to figure it out for yourself. A couple of years ago, in the Roadrunner days, they did make that sort of information available. By the way, I only knew about the nameservers because my router told me. For whatever it's worth, the nameservers I use on Comcast are: 63.240.76.19 204.127.198.19 I think they actually have a third one but I don't know what it is. Paul Abrahams
On Saturday 31 January 2004 04:01 pm, Paul W. Abrahams wrote:
They won't even tell you what their nameservers are -- you have to figure it out for yourself. A couple of years ago, in the Roadrunner days, they did make that sort of information available.
If you really want to know their DNS then go to a registration outfit like register.com and look up your provider by name, i.e., earthlink.net, comcast.net, comcast.com with their search function, then click on the View Whois for the ones you find and you will get all the DNS you can stand. It's no deep dark secret, probably some drone feeling a little bit of power or more likely showing his stupidity. I once got the same runaround from some flunky at roadrunner. I have a bottle of eyeglass cleaner that is smarter than most of them! Richard
On Saturday 31 January 2004 6:02 am, Richard Atcheson wrote:
On Saturday 31 January 2004 04:01 pm, Paul W. Abrahams wrote:
They won't even tell you what their nameservers are -- you have to figure it out for yourself. A couple of years ago, in the Roadrunner days, they did make that sort of information available.
If you really want to know their DNS then go to a registration outfit like register.com and look up your provider by name, i.e., earthlink.net, comcast.net, comcast.com with their search function, then click on the View Whois for the ones you find and you will get all the DNS you can stand.
The nameservers I get that way are different from the ones that my router tells me about. Paul Abrahams
On Sun, Feb 01, 2004 at 01:16:10AM -0500, Paul W. Abrahams wrote:
On Saturday 31 January 2004 6:02 am, Richard Atcheson wrote:
If you really want to know their DNS then go to a registration outfit like register.com and look up your provider by name, i.e., earthlink.net, comcast.net, comcast.com with their search function, then click on the View Whois for the ones you find and you will get all the DNS you can stand.
The nameservers I get that way are different from the ones that my router tells me about.
The nameservers you get that way are authoritative for their respective domains and have nothing to do with nameservers your router is pointed to. All you need for your computer is dns lookup. And that could be any server, including running your own on your computer. To learn more have a look at http://cr.yp.to/djbdns/intro-dns.html Regards, -Kastus
* Paul W. Abrahams <abrahams@acm.org> [01-31-04 11:01]:
By the way, I only knew about the nameservers because my router told me. For whatever it's worth, the nameservers I use on Comcast are:
63.240.76.19 204.127.198.19
I think they actually have a third one but I don't know what it is.
I do not know where you got those, but ARIN reports: 24.128.1.82 24.130.1.43 24.129.0.103 -- Patrick Shanahan Registered Linux User #207535 http://wahoo.no-ip.org @ http://counter.li.org
On Saturday 31 January 2004 11:16 am, Patrick Shanahan wrote:
I do not know where you got those, but ARIN reports: 24.128.1.82 24.130.1.43 24.129.0.103
I believe it is local comcast monopoly (and multiple DNS servers) specific what nameserver you use INTERNALLY. It comes to me via dhcpcd but is constant more or less. What they show externally is something else. -- _/_/_/ Bob Pearson gottadoit@mailsnare.net _/_/_/ "The best way to get information on Usenet is not to ask a _/_/_/ question, but to post the wrong information." - Aahz' Law
On Saturday 31 January 2004 11:16 am, Patrick Shanahan wrote:
* Paul W. Abrahams <abrahams@acm.org> [01-31-04 11:01]:
By the way, I only knew about the nameservers because my router told me. For whatever it's worth, the nameservers I use on Comcast are:
63.240.76.19 204.127.198.19
I think they actually have a third one but I don't know what it is.
I do not know where you got those, but ARIN reports: 24.128.1.82 24.130.1.43 24.129.0.103
What is ARIN and how can I use it? Paul Abrahams
* Paul W. Abrahams <abrahams@acm.org> [01-31-04 11:33]:
What is ARIN and how can I use it?
:~> whois comcast.net :~> man whois -- Patrick Shanahan Registered Linux User #207535 http://wahoo.no-ip.org @ http://counter.li.org
On Saturday 31 January 2004 11:16 am, Patrick Shanahan wrote:
I do not know where you got those [nameservers], but ARIN reports: 24.128.1.82 24.130.1.43 24.129.0.103
Running "whois comcast.net" on my own machine, I get this output: Registrant: Comcast Corporation (COMCAST4-DOM) 1500 Market Street Philadelphia, PA 19102 US Domain Name: COMCAST.NET Administrative Contact: Comcast Online (AC149-ORG) domregadmin@COMCAST.NET 1500 Market St Philadelphia, PA 19102 US 215-564-0132 fax: 215-564-0132 Technical Contact: Technical, Domain Reg (35358439P) domregtech@comcast.net Comcast Communications 1500 Market Street Philadelphia, PA 19102 US 215-564-0132 fax: 215-564-0132 Record expires on 24-Sep-2008. Record created on 25-Sep-1997. Database last updated on 2-Feb-2004 22:47:40 EST. Domain servers in listed order: DNS01.JDC01.PA.COMCAST.NET 68.87.96.3 DNS02.JDC01.PA.COMCAST.NET 68.87.96.4 ------- However, when I went to www.aris.org and typed "comcast.net" in the whois box at the top of the page, I got: Search results for: comcast.net No match found for comcast.net. # ARIN WHOIS database, last updated 2004-02-01 19:15 # Enter ? for additional hints on searching ARIN's WHOIS database. ---- So how did you locate those three nameservers? Paul Abrahams
On Mon, 2004-02-02 at 22:53, Paul W. Abrahams wrote:
On Saturday 31 January 2004 11:16 am, Patrick Shanahan wrote:
I do not know where you got those [nameservers], but ARIN reports: 24.128.1.82 24.130.1.43 24.129.0.103
Running "whois comcast.net" on my own machine, I get this output:
<snip>
Domain servers in listed order:
DNS01.JDC01.PA.COMCAST.NET 68.87.96.3 DNS02.JDC01.PA.COMCAST.NET 68.87.96.4
They are the DNS servers for the comcast.net domain, the servers that point people to *.comcast.net including the MX records. -- Ken Schneider unix user since 1989 linux user since 1994 SuSE user since 1998 (5.2)
On Tuesday 03 February 2004 6:56 am, Kenneth Schneider wrote:
On Mon, 2004-02-02 at 22:53, Paul W. Abrahams wrote:
On Saturday 31 January 2004 11:16 am, Patrick Shanahan wrote:
I do not know where you got those [nameservers], but ARIN reports: 24.128.1.82 24.130.1.43 24.129.0.103
Running "whois comcast.net" on my own machine, I get this output:
<snip>
Domain servers in listed order:
DNS01.JDC01.PA.COMCAST.NET 68.87.96.3 DNS02.JDC01.PA.COMCAST.NET 68.87.96.4
They are the DNS servers for the comcast.net domain, the servers that point people to *.comcast.net including the MX records.
So how did Patrick find the three 24.x.x.x nameservers? Not with whois as far as I can tell. Paul Abrahams
* Paul W. Abrahams <abrahams@acm.org> [02-02-04 22:59]:
So how did you locate those three nameservers?
re: partial header from mail you posted to me: Received: from sccrmhc11.comcast.net (sccrmhc11.comcast.net [204.127.202.55]) by wahoo.no-ip.org (Postfix) with ESMTP id 50FBB633F8 for <paka@wahoo.no-ip.org>; Wed, 28 Jan 2004 00:22:16 -0500 (EST) Received: from suillus.local (h002078d6b671.ne.client2.attbi.com[24.91.182.73]) by comcast.net (sccrmhc11) with SMTP id <2004012805221501100jeob8e>; Wed, 28 Jan 2004 05:22:15 +0000 From: "Paul W. Abrahams" <abrahams@acm.org> from that header: (h002078d6b671.ne.client2.attbi.com[24.91.182.73]) pat@wahoo:~> /usr/sbin/traceroute 24.91.182.73 traceroute to 24.91.182.73 (24.91.182.73), 30 hops max, 40 byte packets x .......... 16 bar02-p7-0.ndhmhe1.ma.attbb.net (24.91.0.46) 51.224 ms 50.757 ms 52.968 ms 17 bar01-p0-0.wsfdhe1.ma.attbb.net (24.128.0.102) 59.678 ms 62.060 ms 64.076 ms 18 bar01-p0-0.natnhe1.ma.attbb.net (24.128.190.198) 66.459 ms 68.591 ms 70.722 ms 19 bar01-p0-1.drfdhe1.ma.attbb.net (24.91.0.82) 73.010 ms 75.044 ms 76.724 ms 20 ubr01-p2-0.drfdhe1.ma.attbb.net (24.91.0.90) 79.511 ms 81.961 ms 84.036 ms 21 h002078d6b671.ne.client2.attbi.com (24.91.182.73) 56.298 ms 58.441 ms 60.329 ms pat@wahoo:~> whois 24.91.182.73 GeekTools Whois Proxy v5.0.3 Ready. Checking access for 24.208.208.146... ok. Final results obtained from whois.arin.net. Results: OrgName: Comcast Cable Communications Holdings, Inc OrgID: CCCH-3 Address: 3 Executive Campus Address: 5th Campus City: Cherry Hill StateProv: NJ PostalCode: 08002 Country: US NetRange: 24.91.0.0 - 24.91.255.255 CIDR: 24.91.0.0/16 NetName: RW2-NORTHEAST-2 NetHandle: NET-24-91-0-0-1 Parent: NET-24-0-0-0-0 NetType: Direct Allocation NameServer: NS4.ATTBB.NET NameServer: NS5.ATTBB.NET NameServer: NS6.ATTBB.NET Comment: RegDate: Updated: 2003-08-06 OrgAbuseHandle: NAPO-ARIN OrgAbuseName: Network Abuse and Policy Observance OrgAbusePhone: +1-856-317-7272 OrgAbuseEmail: abuse@comcast.net OrgTechHandle: IC161-ARIN OrgTechName: Comcast Cable Communications Inc OrgTechPhone: +1-856-317-7200 OrgTechEmail: cips_ip-registration@cable.comcast.com # ARIN WHOIS database, last updated 2004-02-02 22:49 # Enter ? for additional hints on searching ARIN's WHOIS database. Results brought to you by the GeekTools WHOIS Proxy Server results may be copyrighted and are used with permission. Your host (24.208.208.146) has visited 4 times today. NameServer: NS4.ATTBB.NET 24.128.1.82 NameServer: NS5.ATTBB.NET 24.130.1.43 NameServer: NS6.ATTBB.NET 24.129.0.103 Seems you are local to attbb.net (attbi.com, 24.91.182.73) and they use ns?.attbb.net for nameservers, that would be local to you also. Local should be quicker ???? and quicker/faster resolution should get you better performance web-wise ??? Please advise if my thought process is convoluted. -- Patrick Shanahan Registered Linux User #207535 http://wahoo.no-ip.org @ http://counter.li.org
On Tuesday 03 February 2004 8:00 am, Patrick Shanahan wrote:
pat@wahoo:~> /usr/sbin/traceroute 24.91.182.73 traceroute to 24.91.182.73 (24.91.182.73), 30 hops max, 40 byte packets x ..........
Traceroute doesn't seem to work for me because (I assume) I'm sitting behind a router. Here's what the same traceroute gives me: pwa@suillus:~> traceroute 24.91.182.73 traceroute to 24.91.182.73 (24.91.182.73), 30 hops max, 40 byte packets 1 router (192.168.1.1) 0.988 ms 0.581 ms 0.597 ms Any suggestions on how to get traceroute to work in a more revealing way? By the way, my apologies for posting my question twice. The second posting was before I saw your answer. Paul Abrahams
* Paul W. Abrahams <abrahams@acm.org> [02-03-04 14:15]:
Traceroute doesn't seem to work for me because (I assume) I'm sitting behind a router. Here's what the same traceroute gives me:
I am behind a router also. Everyone should be, or a box used as a router, IMNSHO.
pwa@suillus:~> traceroute 24.91.182.73 traceroute to 24.91.182.73 (24.91.182.73), 30 hops max, 40 byte packets 1 router (192.168.1.1) 0.988 ms 0.581 ms 0.597 ms
IIANM, 24.91.182.73 is you, thus it finishes at your router. 24... is the address your email appears to be _from_.
Any suggestions on how to get traceroute to work in a more revealing way?
Try doing a trace to me, 24.208.208.146.
By the way, my apologies for posting my question twice. The second posting was before I saw your answer.
not a problem. BUT, we both probably need to know more about, have a better understanding of the internet and network design. AIUI, the router is a block that you may program to allow/disallow traffic from/to/thru the internet. When I do a traceroute to anywhere outside my router, the router is always the first address listed. I would guess that your router address is 192.168.1.1, mine is 192.168.0.1. I believe that _all_ the 192..... block is internal addressing. Perhaps you have not programmed (is it necessary) your router to allow traceroute traffic outside ?? -- Patrick Shanahan Registered Linux User #207535 http://wahoo.no-ip.org @ http://counter.li.org
On Tuesday 03 February 2004 4:21 pm, Patrick Shanahan wrote:
Try doing a trace to me, 24.208.208.146.
I get: traceroute to 24.208.208.146 (24.208.208.146), 30 hops max, 40 byte packets 1 * * * 2 * * * <snip> 30 * * * I guess my router (a Linksys) is blocking the traceroute somehow. I'd like to learn more about what's safe and not safe in opening it up. Paul Abrahams
I should have asked explicitly: given my MAC address, how do I determine the associated hostname? Can I ping it? Is there still a fixed associated hostname on Comcast? A Google search yielded posts that suggests Comcast might be changing their practices on that. Paul Abrahams
* Paul W. Abrahams <abrahams@acm.org> [01-31-04 11:37]:
I should have asked explicitly: given my MAC address, how do I determine the associated hostname? Can I ping it? Is there still a fixed associated hostname on Comcast? A Google search yielded posts that suggests Comcast might be changing their practices on that.
IIANM, your MAC address is only good for internal/local networks and for comcast to identify your account. You are _not_ identified on the net by your mac address. Your host/domain address resolves to a dotted quad ###.###.###.### and this is used to identify you on the net/web. The word names are a handy way of remembering place-names instead of learning/remembering a string of disassociated numbers. If you do not have a static address, your address changes periodically, although it may not appear to. My address 24.208.208.146 has been the same for nearly two years, and I would prefer that it never changes. -- Patrick Shanahan Registered Linux User #207535 http://wahoo.no-ip.org @ http://counter.li.org
Patrick Shanahan wrote:
* Paul W. Abrahams <abrahams@acm.org> [01-31-04 11:37]:
I should have asked explicitly: given my MAC address, how do I determine the associated hostname? Can I ping it? Is there still a fixed associated hostname on Comcast? A Google search yielded posts that suggests Comcast might be changing their practices on that.
IIANM, your MAC address is only good for internal/local networks and for comcast to identify your account. You are _not_ identified on the net by your mac address. Your host/domain address resolves to a dotted quad ###.###.###.### and this is used to identify you on the net/web. The word names are a handy way of remembering place-names instead of learning/remembering a string of disassociated numbers.
If you do not have a static address, your address changes periodically, although it may not appear to. My address 24.208.208.146 has been the same for nearly two years, and I would prefer that it never changes.
Unlike what appears to be happening on ADSL, cable modem users tend to have long term dhcp leases.
The Saturday 2004-01-31 at 12:05 -0500, Patrick Shanahan wrote:
IIANM, your MAC address is only good for internal/local networks and for comcast to identify your account. You are _not_ identified on the net by your mac address. Your host/domain address resolves to a dotted
MAC addresses were suppossed to be world wide unique: a part of the address identified the card maker, the rest the card itself; of course, that doesn't mean you can find any computer given the mac address. And MAC addresses can be spoofed, so all this might not be true nowdays. -- Cheers, Carlos Robinson
On Tuesday 03 February 2004 9:35 pm, Carlos E. R. wrote:
MAC addresses were supposed to be world wide unique: a part of the address identified the card maker, the rest the card itself; of course, that doesn't mean you can find any computer given the mac address. And MAC addresses can be spoofed, so all this might not be true nowdays.
The confusion arises because what is true in particular is not true in general. For Comcast customers (and presumably those of some other net vendors also) it is true that you can find the hostname of the customer's computer if you know its MAC address. But it is emphatically not true that you can find the hostname (or IP address) of an arbitrary computer, given its MAC address. Paul Abrahams
The Tuesday 2004-02-03 at 22:49 -0500, Paul W. Abrahams wrote:
MAC addresses were supposed to be world wide unique: a part of the address identified the card maker, the rest the card itself; of course, that doesn't mean you can find any computer given the mac address. And MAC addresses can be spoofed, so all this might not be true nowdays.
The confusion arises because what is true in particular is not true in general. For Comcast customers (and presumably those of some other net vendors also) it is true that you can find the hostname of the customer's computer if you know its MAC address. But it is emphatically not true that you can find the hostname (or IP address) of an arbitrary computer, given its MAC address.
I understood that already :-) But that was not my meaning. MAC hardware addresses, or ethernet addresses, in numeric form, were designed originally to be universally unique, in hardware, unchangeable. Card makers applied for a registered maker number, and then added serial numbers of their own, never repeating a number. Thus, any card on the world was supposed to have unique numerical hardware addresses. I stress "supposedly" :-) Nevertheless, that doesn't mean you can reach any computer by it's MAC address, unless it is on your ethernet LAN. On the other hand, there is that interesting trick of Comcast of using an internet naming scheme with names formed from the mac address. Interesting trick, it's new for me. I hope I clarified my meaning? :-) -- Cheers, Carlos Robinson
-----Original Message----- From: "Paul W. Abrahams" <abrahams@acm.org> To: suse-linux-e@suse.com Date: Sat, 31 Jan 2004 11:36:45 -0500 Subject: Re: [SLE] Comcast and NAT
I should have asked explicitly: given my MAC address, how do I determine the associated hostname? Can I ping it? Is there still a fixed associated hostname on Comcast? A Google search yielded posts that suggests Comcast might be changing their practices on that.
Hostnames are not associated with MAC addresses, they are associated with IP addresses. The first place to look is in your /etc/hosts file. If you have aregistered domain name you need to look at dyndns.org for name resolution. Ken
On Saturday 31 January 2004 12:24 pm, Ken Schneider wrote:
Hostnames are not associated with MAC addresses, they are associated with IP addresses.
I seem to recall that one of the predecessors of Comcast (Roadrunner? AT&T Broadband?) actually assigned real, honest-to-goodness hostnames to each customer that were derived from the MAC address. Maybe that's not the case any more. But James Knott wrote in a recent post:
Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
That's what led me to ask the question. And by the way, is there a utility that will take an IP address as input and return the corresponding hostname as output? If so, I might be able to use that to determine my MAC-based hostname. Paul Abrahams
On Saturday 31 January 2004 18.58, Paul W. Abrahams wrote:
And by the way, is there a utility that will take an IP address as input and return the corresponding hostname as output? If so, I might be able to use that to determine my MAC-based hostname.
dig -x <ip-address>
-----Original Message----- From: "Paul W. Abrahams" <abrahams@acm.org> To: suse-linux-e@suse.com Date: Sat, 31 Jan 2004 12:58:01 -0500 Subject: Re: [SLE] Comcast and NAT
On Saturday 31 January 2004 12:24 pm, Ken Schneider wrote:
Hostnames are not associated with MAC addresses, they are associated with IP addresses.
I seem to recall that one of the predecessors of Comcast (Roadrunner? AT&T Broadband?) actually assigned real, honest-to-goodness hostnames to each customer that were derived from the MAC address. Maybe that's not the case any more. But James Knott wrote in a recent post:
Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
That's what led me to ask the question.
And by the way, is there a utility that will take an IP address as input and return the corresponding hostname as output? If so, I might be able to use that to determine my MAC-based hostname.
Again hostnames are IP based -not- MAC based. What Comcast did was register your MAC address into there database to make sure only one PC was using the service. MAC addresses are only used at the hardware level IAANM. Use the host command to find the hostname associated with an address. This uses DNS so unless you set up your own DNS server it most likely will not help you. To learn more about IP addresses/hostname associations and about DNS I recommend a book ny O'Reilly and Assoc. called DNS and Bind. Ken
On Saturday 31 January 2004 19.09, Ken Schneider wrote:
Again hostnames are IP based -not- MAC based. What Comcast did was register your MAC address into there database to make sure only one PC was using the service. MAC addresses are only used at the hardware level IAANM.
It is perfectly possible to set up a DHCP/DNS server to always give the same IP to a certain MAC address, and/or update the DNS server so the same name always points to the same MAC
-----Original Message----- From: Anders Johansson <andjoh@rydsbo.net> To: suse-linux-e@suse.com Date: Sat, 31 Jan 2004 19:18:19 +0100 Subject: Re: [SLE] Comcast and NAT
On Saturday 31 January 2004 19.09, Ken Schneider wrote:
Again hostnames are IP based -not- MAC based. What Comcast did was register your MAC address into there database to make sure only one PC was using the service. MAC addresses are only used at the hardware level IAANM.
It is perfectly possible to set up a DHCP/DNS server to always give the same IP to a certain MAC address, and/or update the DNS server so the same name always points to the same MAC
Yes DHCP can be setup to asign a specific address to a MAC address. And DNS can be setup to associate a specific hostname to the IP address assigned. Ken
On Saturday 31 January 2004 1:09 pm, Ken Schneider wrote:
Again hostnames are IP based -not- MAC based. What Comcast did was register your MAC address into there database to make sure only one PC was using the service. MAC addresses are only used at the hardware level IAANM.
Use the host command to find the hostname associated with an address. This uses DNS so unless you set up your own DNS server it most likely will not help you.
I did understand that there's in general no connection at all between MAC addresses and hostnames. But there can be in particular cases, as the following test shows. I found my outbound IP address by querying my router control program (there are other, simpler ways to do that, I suppose). Then, using your helpful hint, I did: pwa@suillus:~> host 24.91.182.73 73.182.91.24.in-addr.arpa domain name pointer h002078d6b671.ne.client2.attbi.com. And indeed: -- my MAC address is 002078d6b671 -- pinging the attbi address above works An interesting sidelight on all this is that my "secret" stable hostname (the one Comcast doesn't seem to want me to know about) is in an attbi domain, not a Comcast domain. So it may not last forever. Paul Abrahams
On Saturday 31 January 2004 12:47, Paul W. Abrahams wrote:
On Saturday 31 January 2004 1:09 pm, Ken Schneider wrote: <SNIP> I did understand that there's in general no connection at all between MAC addresses and hostnames. But there can be in particular cases, as the following test shows.
I found my outbound IP address by querying my router control program (there are other, simpler ways to do that, I suppose). Then, using your helpful hint, I did:
pwa@suillus:~> host 24.91.182.73 73.182.91.24.in-addr.arpa domain name pointer h002078d6b671.ne.client2.attbi.com.
And indeed:
-- my MAC address is 002078d6b671 -- pinging the attbi address above works
An interesting sidelight on all this is that my "secret" stable hostname (the one Comcast doesn't seem to want me to know about) is in an attbi domain, not a Comcast domain. So it may not last forever.
I have been following this thread with great interest! I gather that you are streaming comcast(?) but how does a linux user *receive* the stream? ...CH
Paul Abrahams
On Saturday 31 January 2004 2:27 pm, C Hamel wrote:
I have been following this thread with great interest! I gather that you are streaming comcast(?) but how does a linux user *receive* the stream?
Pardon my ignorance -- but what do you mean by "streaming" Comcast? I have Comcast as my ISP and I do my email and web browsing through them; so far I have not attempted any form of webpage or ftp hosting. Paul Abrahams
On Saturday 31 January 2004 14:31, Paul W. Abrahams wrote:
Pardon my ignorance -- but what do you mean by "streaming" Comcast? I have Comcast as my ISP and I do my email and web browsing through them; so far I have not attempted any form of webpage or ftp hosting.
No... please pardon MY ignorance! I joined this list late, apparently. :-\ As you were! ;-) ...CH
C Hamel wrote:
On Saturday 31 January 2004 12:47, Paul W. Abrahams wrote:
On Saturday 31 January 2004 1:09 pm, Ken Schneider wrote:
<SNIP>
I did understand that there's in general no connection at all between MAC addresses and hostnames. But there can be in particular cases, as the following test shows.
I found my outbound IP address by querying my router control program (there are other, simpler ways to do that, I suppose). Then, using your helpful hint, I did:
pwa@suillus:~> host 24.91.182.73 73.182.91.24.in-addr.arpa domain name pointer h002078d6b671.ne.client2.attbi.com.
And indeed:
-- my MAC address is 002078d6b671 -- pinging the attbi address above works
An interesting sidelight on all this is that my "secret" stable hostname (the one Comcast doesn't seem to want me to know about) is in an attbi domain, not a Comcast domain. So it may not last forever.
I have been following this thread with great interest! I gather that you are streaming comcast(?) but how does a linux user *receive* the stream?
What do you mean by "streaming"?
Paul W. Abrahams wrote:
On Saturday 31 January 2004 1:09 pm, Ken Schneider wrote:
Again hostnames are IP based -not- MAC based. What Comcast did was register your MAC address into there database to make sure only one PC was using the service. MAC addresses are only used at the hardware level IAANM.
Use the host command to find the hostname associated with an address. This uses DNS so unless you set up your own DNS server it most likely will not help you.
I did understand that there's in general no connection at all between MAC addresses and hostnames. But there can be in particular cases, as the following test shows.
I found my outbound IP address by querying my router control program (there are other, simpler ways to do that, I suppose). Then, using your helpful hint, I did:
pwa@suillus:~> host 24.91.182.73 73.182.91.24.in-addr.arpa domain name pointer h002078d6b671.ne.client2.attbi.com.
And indeed:
-- my MAC address is 002078d6b671 -- pinging the attbi address above works
An interesting sidelight on all this is that my "secret" stable hostname (the one Comcast doesn't seem to want me to know about) is in an attbi domain, not a Comcast domain. So it may not last forever.
Maybe not, but it will last through dhcp IP changes.
Ken Schneider wrote:
-----Original Message----- From: "Paul W. Abrahams" <abrahams@acm.org> To: suse-linux-e@suse.com Date: Sat, 31 Jan 2004 12:58:01 -0500 Subject: Re: [SLE] Comcast and NAT
On Saturday 31 January 2004 12:24 pm, Ken Schneider wrote:
Hostnames are not associated with MAC addresses, they are associated
with
IP addresses.
I seem to recall that one of the predecessors of Comcast (Roadrunner? AT&T Broadband?) actually assigned real, honest-to-goodness hostnames to each customer that were derived from the MAC address. Maybe that's not the case any more. But James Knott wrote in a recent post:
Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look
up
will return the correct ip.
That's what led me to ask the question.
And by the way, is there a utility that will take an IP address as input and return the corresponding hostname as output? If so, I might be able to use that to determine my MAC-based hostname.
Again hostnames are IP based -not- MAC based. What Comcast did was register your MAC address into there database to make sure only one PC was using the service. MAC addresses are only used at the hardware level IAANM.
Again, my host name contains my firewall and cable modem mac addresses. They are static.
On Sat, Jan 31, 2004 at 12:58:01PM -0500, Paul W. Abrahams wrote:
And by the way, is there a utility that will take an IP address as input and return the corresponding hostname as output?
dnsname from djbdns, host or dig from bind-utils Regards, -Kastus
On Saturday 31 January 2004 12:58 pm, Paul W. Abrahams wrote:
On Saturday 31 January 2004 12:24 pm, Ken Schneider wrote:
Hostnames are not associated with MAC addresses, they are associated with IP addresses.
I seem to recall that one of the predecessors of Comcast (Roadrunner? AT&T Broadband?) actually assigned real, honest-to-goodness hostnames to each customer that were derived from the MAC address. Maybe that's not the case
any more.
I know that bootp uses 48-bit ethernet addresses to assign IP addresses and DHCP servers support BOOTP client sematics (that is, here is my MAC address, now give me my IP address). From http://www.ietf.org/rfc/rfc2131.txt?number=2131 DHCP supports three mechanisms for IP address allocation. In "automatic allocation", DHCP assigns a permanent IP address to a client. In "dynamic allocation", DHCP assigns an IP address to a client for a limited period of time (or until the client explicitly relinquishes the address). In "manual allocation", a client's IP address is assigned by the network administrator, and DHCP is used simply to convey the assigned address to the client. A particular network will use one or more of these mechanisms, depending on the policies of the network administrator. -- _/_/_/ Bob Pearson gottadoit@mailsnare.net _/_/_/ "The best way to get information on Usenet is not to ask a _/_/_/ question, but to post the wrong information." - Aahz' Law
Paul W. Abrahams wrote:
On Saturday 31 January 2004 12:24 pm, Ken Schneider wrote:
Hostnames are not associated with MAC addresses, they are associated with IP addresses.
I seem to recall that one of the predecessors of Comcast (Roadrunner? AT&T Broadband?) actually assigned real, honest-to-goodness hostnames to each customer that were derived from the MAC address. Maybe that's not the case any more. But James Knott wrote in a recent post:
Also, while my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
That's what led me to ask the question.
And by the way, is there a utility that will take an IP address as input and return the corresponding hostname as output? If so, I might be able to use that to determine my MAC-based hostname.
man host
Paul W. Abrahams wrote:
I should have asked explicitly: given my MAC address, how do I determine the associated hostname? Can I ping it? Is there still a fixed associated hostname on Comcast? A Google search yielded posts that suggests Comcast might be changing their practices on that.
You can find your name from your IP, using the host command, as I showed in a previous message. You should be able to get your IP from the router.
Paul W. Abrahams wrote:
On Friday 30 January 2004 11:25 pm, James Knott wrote:
While my address may change, my host name won't, as it's based on my mac address. So any host name look up will return the correct ip.
I remember knowing that I did have a fixed hostname related to my MAC address, but I don't remember how to figure out what it is. Comcast is very reluctant to provide technical information about anything other than the standard vanilla Windows connection. They won't even tell you what their nameservers are -- you have to figure it out for yourself. A couple of years ago, in the Roadrunner days, they did make that sort of information available.
By the way, I only knew about the nameservers because my router told me. For whatever it's worth, the nameservers I use on Comcast are:
63.240.76.19 204.127.198.19
I think they actually have a third one but I don't know what it is.
Use the host command to obtain the host name for an IP address. For example: $ host 63.240.76.19 19.76.240.63.in-addr.arpa domain name pointer ns10.attbi.com. Do the same thing with your own IP to find your host name.
On Friday 30 January 2004 18:27, Paul W. Abrahams wrote:
How can you set up a server with a Comcast account if your IP address is not static and therefore subject to change without notice?
www.dyndns.org -- _____________________________________ John Andersen
Damon Register wrote:
In another post I commented that I had trouble yesterday with what seems to be Comcast blocking ports 21 and 80 so I couldn't serve ftp or http. I mentioned this to my brother who said he remembers reading somewhere that Comcast is "going after people running NAT" but he didn't remember any more. Has anyone else heard this? How would NAT be detected with SuSEfirewall2 on 9.0?
I wouldn't think they could, but try it from the computer closest to the modem. Did you call Comcast? Is your IPTables blocking it?
On Mon, 2004-01-26 at 16:12, James Knott wrote:
Damon Register wrote:
In another post I commented that I had trouble yesterday with what seems to be Comcast blocking ports 21 and 80 so I couldn't serve ftp or http. I mentioned this to my brother who said he remembers reading somewhere that Comcast is "going after people running NAT" but he didn't remember any more. Has anyone else heard this? How would NAT be detected with SuSEfirewall2 on 9.0?
Adelphia is doing that too. I setup my firewall to have port 81 go to my computer's port 80. What's the point of the internet if folks can't host their own websites??? Adelphia doesn't condone NAT either. They won't help with problems if one is running a NAT'd system....but they don't know how to help with Linux anyway, so I don't see the problem. I don't see how Comcast could "go after" someone. The worst that could probably happen is they tell you to stop it. Tom -- Tom Nielsen Neuro Logic Systems 805.389.5435 x18 www.neuro-logic.com
participants (15)
-
Adalberto Castelo -
Anders Johansson -
Bob Pearson -
C Hamel -
Carlos E. R. -
Damon Register -
James Knott -
John Andersen -
Kastus -
Ken Schneider -
Kenneth Schneider
-
Patrick Shanahan -
Paul W. Abrahams -
Richard Atcheson -
Tom Nielsen