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| -rw-r--r-- | content/guide/stuff-about-dns-and-ip.md (renamed from content/guide/stuff-about-dns.md) | 109 |
1 files changed, 79 insertions, 30 deletions
diff --git a/content/guide/stuff-about-dns.md b/content/guide/stuff-about-dns-and-ip.md index 06c3956..b336d30 100644 --- a/content/guide/stuff-about-dns.md +++ b/content/guide/stuff-about-dns-and-ip.md @@ -1,5 +1,5 @@ --- -title: Stuff about dns +title: Stuff about DNS and IP date: 2025-10-27T13:46:54+01:00 draft: true index: false @@ -25,7 +25,7 @@ There are two kinds of IP addresses; IPv4 and IPv6. Try to get your local IPv4 address in your local network : ```sh -ip a | grep "inet .*" +ip a | grep "inet " # You might get something like the following : inet 127.0.0.1/8 .... # your localhost @@ -38,16 +38,13 @@ You can even ping yourself or other devices in your house that are connected to ping -c 2 192.0.2.1 # or localhost, ping yourself ``` -You can get your public IPv4 by going to websites that tell you your IP like [whatismyipaddress.com/](https://whatismyipaddress.com/) +You can get your public IPv4 by going to websites that tell you your IP like [whatismyipaddress.com](https://whatismyipaddress.com/) or [ifconfig.co](https://ifconfig.co) -Or curl [ifconfig.co](https://ifconfig.co) like so : +You can also do it from the command line : ```sh -curl ifconfig.co # gives you your public IPv6 -curl -6 ifconfig.co # it also works -``` -```sh -curl -4 ifconfig.co # gives you your public IPv4 +curl -6 ifconfig.co # gives IPv6 +curl -4 ifconfig.co # gives IPv4 ``` ### What's your Wi-Fi router local IP ? @@ -55,7 +52,7 @@ curl -4 ifconfig.co # gives you your public IPv4 Just use the `ip` command again : ```sh -ip route | grep default +ip r | grep default # You will get something like default via IP_ADDRESS ... @@ -65,18 +62,19 @@ If your ISP (Internet Service Provider) allows it, you can put the `IP_ADDRESS` The password is probably the one you use to connect to Wi-Fi. -### Can't open ports in range [0, 32765[ +### Can't open ports in range (0, 32765) I had this problem. It's a serious issue if you are trying to self host because the HTTP/HTTPS port and tons of others are in this range. -Personally, I just went to the website of my ISP and there was an option to get a "static full stack IPv4 address". Maybe you should call your ISP I don't know. +To open these ports, I just went to the website of my ISP and there was an option to get a "static, full stack IPv4 address". Just some _thing_ to enable for free. The mail ports were also closed, I had to open them through the same website. + +Since then, I can open the ports I want (and send emails). ## DNS ### What is this ? -DNS (Domain Name System) is pretty cool, it's a fancy _alias_ for IP adresses. See it like a `Dictionnary` data structure in programming. - +DNS (Domain Name System) is pretty cool, it's a fancy _alias_ for IP adresses. So basically, you have a domain name that points to an IP address. ```txt @@ -87,17 +85,21 @@ This is possible by setting DNS records. You set "A" record that bind the domain Domain names are cool and convenient. It would be a pain to remember the IP addresses of my favourite websites. +You also have subdomains. Like [dns.mielota.com](https://dns.mielota.com), `dns` is a subdomain of [mielota.com](/). With the help of a webserver like [NGINX](https://nginx.org) you can ask your server to serve different kind of content depending on the domain/subdomains. + +You also have "CNAME" records, they act like _alias_. "MX" records are for _Mail Exchange_ and "TXT" store some data. + ### DNS resolvers -A DNS resolver is a server that translates domain names into IP addresses. See it like _getter_ function : +A DNS resolver is a server that translates domain names into IP addresses. See it like some function : -```lua -get_ip_from_domain_name("example.com") -- Returns 23.220.75.245 +```py +get_ip_from("example.com") # Returns 23.220.75.245 ``` -Some DNS resolvers have really weird IP addresses. There's 1.1.1.1 (cloudflare), 8.8.8.8 (google), 9.9.9.9 (quad9). I wonder how they even got them. +Commons DNS resolvers have really weird IP addresses. There's 1.1.1.1 (cloudflare), 8.8.8.8 (google), 9.9.9.9 (quad9). I wonder how they even got them. -Try one of them yourself. Send a DNS query for whatever domain name, to one of these DNS resolvers. +Try one of them yourself. Send a DNS query to one of these DNS resolvers to get the IP of some domain name. Install the `dig` command first. @@ -106,48 +108,95 @@ sudo pacman -S bind # On Arch sudo apt install dnsutils # On Debian ``` +(Note that you can pass in the `+short` arg to the `dig` command if you don't like the verbose output) + Now you can query some DNS resolver : ```sh dig example.com @1.1.1.1 ``` -> Note that some DNS providers are unsafe and/or log the IP of websites you connect to. Choose your DNS resolver carefully. Also know that using DNS over HTTPS or DNS over TLS doesn't make you invisible. +> Note that some DNS resolvers are unsafe and/or log the IP of websites you connect to. Choose your DNS resolver carefully. Also know that using DNS over HTTPS or DNS over TLS doesn't make you invisible. ### Control the websites you can visit You can filter the responses of DNS resolvers with programs like [blocky](https://0xerr0r.github.io/blocky/latest/). -You can ask `blocky` to redirect some domain names to the null IP 0.0.0.0. By doing so you can stop your computer/browser/phone from querying websites containing ads, malware, or [unwanted content](https://denshi.org/antiporn). +You can ask `blocky` to redirect some domain names to the null IP 0.0.0.0. For example you can add `example.com` to your "blacklist" and you will get this : + +```sh +dig example.com @your_custom_dns +# you will get 0.0.0.0 +``` -For example ask for the IP of `ads.google.com` : +By doing so you can stop your computer/browser/phone from finding websites containing ads, malware, or [unwanted content](https://denshi.org/antiporn). + +For example ask for the IP of `ads.google.com` to the 8.8.8.8 DNS server: ```sh -dig ads.google.com @8.8.8.8 +dig +short ads.google.com @8.8.8.8 ``` -You got the IP address right ? Now try with my DNS resolver : +You got the IP address right ? Now do the same with my DNS server: ```sh -dig ads.google.com @dns.mielota.com # or put the IPv4 of my server +dig +short ads.google.com @dns.mielota.com # or put the IPv4 of my server ``` You will get 0.0.0.0 -Here are some useful links if you want to do the same : +Here are some useful links if you want to use blocky on your server/computer. + +- [Blocky DNS](https://0xerr0r.github.io/blocky/latest/) - [Comfy Guide to Blocky](https://comfy.guide/server/blocky) - [Comfy Guide to Blocky (video)](https://www.youtube.com/watch?v=Uq6mafo9fEc) -- [Blocky DNS](https://0xerr0r.github.io/blocky/latest/) -You can also run `blocky` locally and query your `localhost`. +Use this command to get the blacklists I use (if you want the same ones): + +```sh +curl -fsSL "https://codeberg.org/mielota/dox/raw/branch/main/opt/blocky/blocky.yml" | grep -o "\- http.*" +``` + +### Get records of a domain name + +You can see what DNS records are setup for domain names too. For example, ask for the A record of my domain name : + +```sh +dig +short A mielota.com +``` + +You can get the MX records of let's say, GitHub : + +```sh +dig +short MX github.com +``` + +You can of course ask for AAAA, TXT, CNAME etc. ### Reverse DNS If you want to setup an email server, you have to setup `reverse DNS`, it's basically DNS but the other way around : Give an IP, get a domain name. -To setup r-dns I had to go to my ISP's website. Some people say that they had to call their ISP. Some people are not allowed to have r-dns. So it's just a matter of luck. +To setup r-DNS I had to go to my ISP's website. Some people say that they had to call their ISP. Some people are not allowed to have r-DNS. So it's just a matter of luck. + +You can see if you have r-DNS with this command : + +```sh +dig +short -x IP_ADDRESS_OF_YOUR_SERVER +``` + +For example you can see that Arch Linux has a working reverse DNS: + +```sh +dig +short -x $(dig +short archlinux.org) # -> "archlinux.org." +``` ## Conclusion ? -These are just some random infos about DNS. Nothing big. Of course, I only covered the **tip** of the iceberg in _whatever_ this is. +These were just some random infos. + +More links : + +- [Check if your DNS records are okay](https://intodns.com/) +- [Addr Tools](https://addr.tools/) |