Tom chasing Harry and Ron Weasly Memeβ€―: Harry :β€―people using the first address of the range as gateway, Ron : people using the last address of the range as gateway, Tom : people using one random address of the range as gateway

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[–] 122 points 5 days ago (8 children)

10.0.0.0/8 address space with a gateway address that gets randomized every 24 hours. Tomorrow's address is advertised on a HTTP server local to the network that cannot be externally accessed. For security reasons.

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  • [–] 45 points 5 days ago (2 children)

    Nothing advertises hostnames, and the DHCP table is dumped and every client gets new address at the same time, too.

    Just make sure the MAC addresses randomize, too, and then you've got yourself a proper fucking mess for a hacker to sort out.

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  • [–] 16 points 5 days ago (3 children)

    I use 10.13.37.42 as my gateway.

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  • [–] 52 points 5 days ago* (last edited 5 days ago) (8 children)

    Gateway is .69

    Dhcp is .70 - .254

    Static routes are .68 and below

    I will not be taking any questions

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  • [–] 18 points 5 days ago (3 children)
  • [–] 9 points 4 days ago (2 children)

    About twenty years ago I was hired in to straighten up a network at a investment place. They were running all static IP addresses and the guy who set it up set the gateway to 69. I laughed and started converting them to dhcp and seriously considered leaving the gateway alone.

    I have to ask a question now. My question is, is that you?

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  • [–] 45 points 5 days ago (12 children)

    Last address? Who the heck does that???

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  • [–] 38 points 5 days ago (3 children)

    I've had modems from my ISP which assigned themselves 192.168.0.254 for some reason. I have no idea why

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  • [–] 7 points 4 days ago

    My guess is that enough people were buying routers and using them as access points. They all tend to be on 192.168.0.1 .254 means you don't get as bad collisions when that happens. It would cut down on technical support calls.

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  • [–] 2 points 4 days ago (3 children)

    There are reasons to put it at the end. For example, 192.168.1.254/24 can be expanded to /23 and have the same gateway address while you migrate clients that are statically assigned or while waiting on DHCP leases to expire, since /23 is a supernet of /24.

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  • [–] 1 point 4 days ago (2 children)

    What am I missing here?

    192.168.1.1/24 would also be a valid gateway for a /23, with the benefit of not having a gateway in the middle of your /23 network?

    I feel like this example is a greater justification for putting the gateway on the network/CIDR + 1, like a civilized person.

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  • [–] 1 point 4 days ago* (last edited 4 days ago) (1 child)

    I shared another post here with how subnetting works. Basically, if you start with 192.168.1.254 on a /24 for your gateway and move to a /23, your usable range goes from 192.168.1.1-192.168.1.254 to 192.168.0.1-192.168.1.254.

    In this situation, the gateway address stays the same and since the /24 is contained within the /23, they can still connect to the gateway and keep working while you migrate things. The only thing they cannot talk to is clients in the 192.168.0.0/24 space until they pull new DHCP or have their static address updated. As such, it can make future expansion easier, if necessary.

    If you used 192.168.1.1/24 as the gateway initially, you'll notice that in this same expansion plan it's now smack in the middle of the subnet in a /23. Is that the end of the world? No, but it looks like shit and complicates things if you did something like I usually do and allocate certain "sections" of the subnet to non-DHCP space. Also, now you need to manage two DHCP pools, one below 192.168.1.1 and one above it. It's one of those small things that compounds with each bandaid until you're dying by a thousand cuts.

    I'm theory you would design your network with a large enough subnet from the get-go for expansion, but sometimes you screw up, so habits like this can make those screw ups less painful.

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  • [–] 2 points 4 days ago

    A typical ip address scheme is to assign lower blocks to dhcp pools and reserve high ip addresses to servers and network gear. Anything over 250 is typically a switch or a router in this case.

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  • [–] 37 points 5 days ago* (last edited 5 days ago) (5 children)

    There's nothing preventing the gateway from being a DHCP client, just saying..

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  • [–] 19 points 5 days ago (2 children)

    oh my god

    i love this idea so much. I've been doing networking for 13 years now and I've never considered a dynamically addressed gateway

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  • [–] 26 points 4 days ago (12 children)

    I used to use 1.2.3.4 as my gateway.

    At the time I didn't understand why this offended ... Basically everybody.

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  • [–] 22 points 4 days ago* (last edited 4 days ago) (11 children)

    As a Network Engineer: If you did this in my presence, I'd burn you at the goddamn stake. πŸ˜‚

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  • [–] 10 points 4 days ago (10 children)

    Like I said ... Basically everybody.

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  • [–] 11 points 4 days ago (9 children)

    That's mostly because it violates established standards, but you know that already. Lol.

    Also, if you're talking to a network engineer, they probably have PTSD dealing with a client that did this with a 1.0.0.0/8 used internally or some shit and now huge swathes of the internet doesn't work, but somehow it's "our fault" that they can't load random web sites.

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  • [–] 6 points 4 days ago (6 children)

    Fwiw, I now use 10.10.220.0/24. I now know what class A, B and C are. I didn't then.

    Hopefully that offers you some comfort.

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  • [–] 4 points 4 days ago (3 children)

    Everyone knows you need to be using a network like fd25:c74c:a5e9::/64. So much more fun that way.

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  • [–] 1 point 4 days ago (1 child)

    I'm sure this is hilarious, but I don't know enough about IPv6 to get it.

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  • [–] 2 points 4 days ago

    It's just a 'proper' IPv6 private address, the IPv6 equivalent of '10.'.

    I say proper as a private address in ipv6 is supposed to be fd, then 40 random bits, then whatever you want. Nothing stops you from having fd::/64 as your private network though. The thinking was people who got tired of merging networks that happened to choose the same 10.x.x.x scheme and/or vpn connecting to multiple sites similarly with the same private address. So they thought it would be swell if every private network on earth would likely be unique, so they said you 'must' randomize 5 bytes of it. Then no renumbering/no conflicting vpn connections.

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  • [–] 3 points 4 days ago (1 child)

    That’s mostly because it violates established standards, but you know that already. Lol.

    Hey, for all you know he might actually be the proper owner of that subnet.....

    I know if by some crazy coincedence I had that in my subnet I'd be using it for fun.

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  • I recently had a ticket for a university that had a /12 of public IPs. They gave every computer, printer, etc. a public IP on their whole network. Nothing has NAT. It was insane. They could buy an entire other university building with the money they'd make selling some of that address space down to even a /24.

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  • [–] 25 points 5 days ago* (last edited 5 days ago) (7 children)

    Meanwhile my gateway is fe80::17a9:3ba7:5Β₯4πŸ”:b8Γ€7%42

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  • [–] 17 points 4 days ago (3 children)

    Wait is there an existing unicode to ipv6 method. I assume it would just be the bit values of the emoji in utf8?

    fe80::"hello πŸ”" aka fe80::6865:6c6c:6f20:f09f:9094

    I approve of the idea of cursed ipv6 notation.

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  • [–] 7 points 4 days ago (1 child)

    That would be a funny way to avoid DNS, just make the address the name.

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  • [–] 2 points 4 days ago (2 children)
  • [–] 2 points 4 days ago (1 child)
  • [–] 1 point 4 days ago

    I’ll be everywhere...wherever you look. Wherever there's a fight so hungry people can eat, I’ll be there. Wherever there's a cop beatin’ up a guy, I’ll be there. I’ll be in the way guys yell when they’re mad...I’ll be in the way kids laugh when they’re hungry and they know supper’s ready. And when our folks eat the stuff they raise and live in the houses they build...I’ll be there.

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  • [–] 25 points 5 days ago (2 children)

    Just set the Gateway to use DHCP.

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  • [–] 18 points 4 days ago (3 children)

    I love that people forget about 127.0.0.0/8 being the loopback network. Everyone just uses .1 when there are so many to choose from.

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  • [–] 5 points 4 days ago (1 child)

    People also commonly do not know that the reserved for intranet ip address range of 192.168.0.0 is actually /16 so you can pick any number between 0 and 255 for that 3rd byte and have their whole network in a range other that 192.168.0.0/8 like pretty much everybody else.

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  • According ding the the law of minimal keystrokes, there's actually only 9 to choose from.

    After applying the law of minimal motion, you're down to even fewer.

    Then you go a step further to just using 127.1 (or your preferred last digit)

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  • [–] 17 points 5 days ago (5 children)

    My home server is at 192.168.1.230 because that's what IP was assigned to the machine at the moment I set it up.

    Yep. Love that chaos, ya know?

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  • [–] 2 points 4 days ago

    Back before i knew anything about networking and set my desktops with statics, i had .1-9 as user devices, .10-19 as servers, .20-29 as printers, .50-59 as networking devices. So my current server is .14 and has been that since uni, DNS is .50, gateway is .51. Now my dhcp pool starts at 100.

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  • [–] 14 points 4 days ago (1 child)

    Subnet: 10/8
    Gateway: 10.2.5.5

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  • [–] 12 points 4 days ago (7 children)

    Nah, put your gateway in a different subnet, but on the same network segment, and add a static /32 route to it on every client.

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  • [–] 2 points 4 days ago (2 children)

    Is there a specific reason behind this? Never considered it but I could see it being useful since most specific routes win.

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  • [–] 4 points 4 days ago (1 child)

    Mostly to make the next sysadmin (or yourself in 6 months) weep. There's nothing preventing there being multiple IP subnets on a single network segment, but you'd usually handle that with separate VLANs, or at least an interface alias, so the machine saw both subnets. About the only reason I could see for just adding a static route would be if you're in the middle of reconfiguring your network to a new subnet but you still need the hosts you haven't updated to be able to route.

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  • [–] 2 points 4 days ago

    The real nightmare when someone puts two ip addresses on the same host through different interfaces. Now that makes for some confusing troubleshooting and explanations in various applications.

    What really gets me is in about 3/4 networks in the last couple of weeks I've been asked to help troubleshoot, the problem has been duplicate IP addresses. I don't know what is going on with people...

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  • [–] 1 point 4 days ago (3 children)

    That won't work, unless I'm misunderstanding you. You'd still need a gateway within your subnet to handle inter-subnet routing or an additional address on the gateway network.

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  • [–] 4 points 4 days ago (1 child)

    It can be made to work, just really really stupid.

    Ultimately the 'gateway' is really a mac address, and the IP is just the thing to ARP to get the mac address. And you can do some gnarly things to pull off things like off-subnet gateway addresses.

    You should never ever do it, but you can if you hate yourself enough.

    Becomes easier in IPv6 to do these shenigans too.

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  • [–] 2 points 4 days ago

    By adding a host, or /32, route to the gateway you should then be able to use it as the default gateway on your main subnet. I was not being serious when I suggested it, as another comment says, it's a pretty stupid idea, and there really isn't any sane usecase for it, except possibly one of those 1am "if it's stupid but it works it's still stupid, but it'll do until morning" type fixes that you shudder to recall years later.

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  • [–] 10 points 5 days ago

    Also change the random address daily without announcing it. If the 7th floor wants internet they can damn well work for it. πŸ˜†

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  • [–] 9 points 5 days ago

    10.10.10.70 here. There was a reason in the distant past that I did this and now it's stuck that way forever.

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