blog // ~ben

a blog about tildes and other things

november 13 post mortem

November 13, 2018 — ~ben

we had something of an outage on november 13, 2018 on tilde.team.

i awoke, not suspecting anything to be amiss. as soon as i logged in to check my email and irc mentions, it became clear.

tilde.team was at the least inaccessible, and at the worst, down completely. according the message in my inbox, there hade been an attempted "attack" from my IP.


We have indications that there was an attack from your server. Please take all necessary measures to avoid this in the future and to solve the issue.

at this point, i have no idea what could have happened over night while i'm sleeping. the timestamp shows that it arrive only 30 minutes after i'd turned in for the night.

when i finally log on in the morning to check mails and irc mentions, i find that i'm unable to connect to tilde.team... strange, but ok; time to troubleshoot. i refresh the webmail to see what i'm missing. it ends up failing to find the server. even stranger! i'd better get the mails off my phone if they're on my @tilde.team mail!

here, i launch in to full debugging mode: what command was it? who ran it?

search ~/.bash_history per user was not very successful. nothing i could find was related to net or map. i had checked sudo grep nmap /home/*/.bash_history and many other commands.

at this point, i had connected with other ~teammates across other irc nets (#!, ~town, etc). among suggestions to check /var/log/syslog, /var/log/kern.log, and dmesg, i finally decided to check ps. ps -ef | grep nmap yielded nmap on an obscured uid and gid, which is shortly established to belong to a container i had provisioned for ~fosslinux.

i'm not considering methods of policing access to any site over port 80 and port 443. this is crazy. how do you police nmap when it isn't scanning on every port?

after a bit of shit-talking and reassurance from other sysadmins, i reexamined and realized that ~fosslinux had only run nmap for addresses in the 10.0.0.0/8 space. the 10/8 address space is intended to not be addressable outside the local space. how could hetzner have found out about a localhost network probe!?

finally, after speaking with more people than i expected to speak with in one day, i ended up sending three different support emails to hetzner support, which finally resulted in them unlocking the ip.

it's definitely time to research redundancy options!

tags: post-mortem, linux, sysadmin