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  1. #1
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    Default cable modem and NAT

    I'm currently trying to suss out NAT setup on a new network:

    Motorola SBG900 cable modem (dynamic IP) with NAT enabled - UT in Router mode - lan.

    Would the correct setup be if I enable DHCP and DNS on UT then disable NAT on the modem the reboot both devices.

    On another matter:
    Also what's the go regarding ADSL setup as I can only see PPPoE in the config setup. I've seen some old posts that UT doesn't support PPPoA. If this is the case is placing UT in router mode outta the question?

    T.I.A.

  2. #2
    mdh
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    Choice #1 would be that your cable modem acts as router (NAT enabled) and hands out DHCP and DNS info. Untangle would sit behind it as a bridge and all LAN traffic would pass through Untangle.

    Choice #2 is that your cable modem has NAT disabled and passes a public IP to your Untangle box, which is configured as a router with DHCP enabled and DNS enabled if you choose to. I have used mine both ways, but I DON'T like putting a router behind a router unless I have enough tequila to make sense out of it when it doesn't work as planned (which is often and irritating).

    I don't know about PPPoA...I had to look it up to find out what it was. I could be totally full of crap on this topic, but "it appears" that PPPoA has a slight bit less overhead than PPPoE in packet structure, making it slightly more efficient. It also sounds like PPPoA is used much less than PPPoE in the ethernet world. Untangle takes traffic apart and puts it back together, and coding has probably not been done for a little-used transport method.

    I'm sure mrunkel can comment with a lot more authority than me on this subject...I'm just trying not to leave you in the dark for hours, wondering if anybody is paying attention.

  3. #3
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    Default sweet or savory?

    Thanks for the reply Mr. Scary give nightmares clown face

    Choice #1 would be that your cable modem acts as router (NAT enabled) and hands out DHCP and DNS info. Untangle would sit behind it as a bridge and all LAN traffic would pass through Untangle.

    I agree this one makes sense as it's so simple to maintain and troubleshoot.
    By having it in Bridge mode though would I be utilizing the Spam and Open vpn effectivley compared to Router mode?

    Choice #2 is that your cable modem has NAT disabled and passes a public IP to your Untangle box, which is configured as a router with DHCP enabled and DNS enabled if you choose to. I have used mine both ways, but I DON'T like putting a router behind a router unless I have enough tequila to make sense out of it when it doesn't work as planned (which is often and irritating).

    Again I agree. I've used the same setup as in that the modem was NAT/DHCP 192.168.0.xxx then UT behind it in Router mode (dynamic IP config) with NAT/DHCP/DNS on 10.0.0.1 lan ? It worked great but then thought why am i doubled NAT-ting so when I dropped NAT off the modem it all went pear shaped as in the UT lost total outside connection then wondered do i now bridge or give it the wans static ip in the config setup???; which cooked my popcorn

    I don't know about PPPoA...I had to look it up to find out what it was. I could be totally full of crap on this topic, but "it appears" that PPPoA has a slight bit less overhead than PPPoE in packet structure, making it slightly more efficient. It also sounds like PPPoA is used much less than PPPoE in the ethernet world. Untangle takes traffic apart and puts it back together, and coding has probably not been done for a little-used transport method.

    Yeah I would like some more feedback on this as I have clients that have adsl and PPPoA setups so I was wondering how to config the network. Do i try PPPoE on the network config. Would that even work?

  4. #4
    Untangle Ninja YeOldeStonecat's Avatar
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    I always setup my own router at clients sites, disabling the router/NAT of the ISP supplied gateway. The ones that the ISP give you are often tolerable, but your own router may have far superior performance and features. So why leave the ISP supplied combo modem/router as your bottleneck and suffer from loss of features and performance?

    So I bridge 'em, and put the static IP on the WAN interface of a router of my choice to protect the clients network (often cases this is an Untangle box )

    I absolutely never..ever..double NAT. No router behind another router.

    Yeah, in the several states I cover up in New England...haven't come across any PPPoA setups, seems to be more popular across the pond.

  5. #5
    mdh
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    Quote Originally Posted by kirkcaine View Post
    Yeah I would like some more feedback on this as I have clients that have adsl and PPPoA setups so I was wondering how to config the network. Do i try PPPoE on the network config. Would that even work?
    From the reading that I did to answer you earlier, it sounds like PPPoE is actually PPPoA with another added layer of encapsulation. I saw it described basically as PPPoEoA (if that makes any sense). My concern there is that Untangle disassembles packets, processes them and reassembles them. They plan on PPPoE or standard ethernet, but not PPPoA. Untangle doesn't provide that third option, so there would likely be difficulties in the disassembly and/or reassembly.

    mrunkel would be able to provide more (and probably more factual) information, and would also be able to talk to developers who could provide definitive answers to the question. I'm just a wingless bird winging it here.

  6. #6
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    I'll drink to you on that as well - the ISP supplied gateways are generally below par and usually come with minimum features. For example on this Motorola SBG900 (cable) the only options I've seen is to turn NAT on/off > Firewall on/off or set the WAN to Static instead of Dynamic assign- no bridge mode no nothing.

    So does that mean I'll have to leave the SBG on NAT/DHCP and disable NAT/DHCP on UT because when I disable NAT on the SBG then input the WAN IP in the STATIC config on UT (phew) it loses external connection.

    Yeah PPPoA is pretty popular over here especially in smb environments so if anyone knows if this can be done then do tell otherwise it'll be bridging time.

  7. #7
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    Quote Originally Posted by mdh View Post
    From the reading that I did to answer you earlier, it sounds like PPPoE is actually PPPoA with another added layer of encapsulation. I saw it described basically as PPPoEoA (if that makes any sense). My concern there is that Untangle disassembles packets, processes them and reassembles them. They plan on PPPoE or standard ethernet, but not PPPoA. Untangle doesn't provide that third option, so there would likely be difficulties in the disassembly and/or reassembly.

    mrunkel would be able to provide more (and probably more factual) information, and would also be able to talk to developers who could provide definitive answers to the question. I'm just a wingless bird winging it here.
    Sorry you did...my eyes are getting tired

  8. #8
    mdh
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    My everything is getting tired. Doing everything I can to not remind myself that there aren't any jobs in the real world anymore. I'll try to get mrunkel to look at this to see if he add anything that is more definitive.

  9. #9
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    Thanks I appreciate the input.

  10. #10
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    Quote Originally Posted by mdh View Post
    My everything is getting tired. Doing everything I can to not remind myself that there aren't any jobs in the real world anymore. I'll try to get mrunkel to look at this to see if he add anything that is more definitive.
    I also think you'll have a hard time confincing yourself on that one lol....There's always someone out there that needs your help...and if (they) know that.... they'll hunt you down lol.....or unless you wear a mask like Mr. Clown then they'll run a mile...Disclaimer - no offence intended if that's how you look though ; )
    Last edited by kirkcaine; 10-29-2009 at 05:52 AM.

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