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EFF adds ASCII art to its DNS

pastebin.ca

11–20 of 32 posts

Re: EFF adds ASCII art to its DNS

#11
post #10
post #3

So, they don't use IP Telephony then? You're aware you can add whatever you want into DNS, it doesn't have to mean anything that computers understand right? you /could/ make your A records the intro to Star Wars- but nobody will be able to use your site. TXT is a much better option imho, or.. y'know, not doing this.

TXT isn't an option because the records themselves are unsorted. Use the above command without the pipe to sort looks weird, but not as weird as TXT would.

MX or with numbers then?

Re: EFF adds ASCII art to its DNS

#12
post #3

So, they don't use IP Telephony then? You're aware you can add whatever you want into DNS, it doesn't have to mean anything that computers understand right? you /could/ make your A records the intro to Star Wars- but nobody will be able to use your site. TXT is a much better option imho, or.. y'know, not doing this.

Which clients use NAPTR? Can't you have a SRV record without NAPTR?

Re: EFF adds ASCII art to its DNS

#13
post #8

Here's the whole thing unsorted: http://pastebin.com/z7BzEnhC and in case you want to learn about NAPTR: http://www.ietf.org/rfc/rfc2915.txt

Regular expressions in DNS records? That sounds like it would be an easy possibility of exponential resource consumption: http://en.wikipedia.org/wiki/ReDoS

After a quick Google, it turns out some versions of ISC BIND were vulnerable to this... but I'm almost willing to bet a lot of other software that handles NAPTR could be as well.

Re: EFF adds ASCII art to its DNS

#14
post #6

My first thought on seeing that is it would be great for a DNS amplification attack. Not sure the value as an advertisement though...

I think it's too big for UDP, it'll renegotiate TCP for anything over a certain size. thus DNS amplification is impossible because spoofing the TCP source would fail a handshake.

The size is 1876 bytes, DNS servers which support EDNS will do up to 4096 byte replies in UDP.

Re: EFF adds ASCII art to its DNS

#16
post #8

Here's the whole thing unsorted: http://pastebin.com/z7BzEnhC and in case you want to learn about NAPTR: http://www.ietf.org/rfc/rfc2915.txt

Regular expressions in DNS records? That sounds like it would be an easy possibility of exponential resource consumption: http://en.wikipedia.org/wiki/ReDoS After a quick Google, it turns out some versions of ISC BIND were vulnerable to this... but I'm almost willing to bet a lot of other software that handles NAPTR could be as well.

Hopefully they use re2[1] or a similar regexp engine without backtracking.

[1]: https://code.google.com/p/re2/

Re: EFF adds ASCII art to its DNS

#17
post #10
post #3

So, they don't use IP Telephony then? You're aware you can add whatever you want into DNS, it doesn't have to mean anything that computers understand right? you /could/ make your A records the intro to Star Wars- but nobody will be able to use your site. TXT is a much better option imho, or.. y'know, not doing this.

TXT isn't an option because the records themselves are unsorted. Use the above command without the pipe to sort looks weird, but not as weird as TXT would.

TXT records are actually variably-sized arrays of strings, making them very suitable for ASCII art. Unfortunately, `dig +short TXT` displays them as

    "string1" "string2" "string3"
instead of on separate lines. However, this is easily remedied with sed.

Using TXT for artwork also has the advantage that you don't risk an intermediate resolver re-ordering things.

Source: When this came up about a month ago: https://news.ycombinator.com/item?id=7185326

Re: EFF adds ASCII art to its DNS

#19
post #10
post #3

So, they don't use IP Telephony then? You're aware you can add whatever you want into DNS, it doesn't have to mean anything that computers understand right? you /could/ make your A records the intro to Star Wars- but nobody will be able to use your site. TXT is a much better option imho, or.. y'know, not doing this.

TXT isn't an option because the records themselves are unsorted. Use the above command without the pipe to sort looks weird, but not as weird as TXT would.

[deleted]

Re: EFF adds ASCII art to its DNS

#20
post #10
post #3

So, they don't use IP Telephony then? You're aware you can add whatever you want into DNS, it doesn't have to mean anything that computers understand right? you /could/ make your A records the intro to Star Wars- but nobody will be able to use your site. TXT is a much better option imho, or.. y'know, not doing this.

TXT isn't an option because the records themselves are unsorted. Use the above command without the pipe to sort looks weird, but not as weird as TXT would.

I really don't think you need to use NAPTR here. Using TXT works just fine, if you do a sort, if you prepend line numbers to the records. Alas, you still have to do a sort. It would be wonderful if there was a hack that involved not using the sort. Here's one I just added: dig txt art.ten7.com |sort
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