All posts by iiidefix

Tmux on login

to start tmux on login add the following to your ~/.bashrc

# Start Tmux by default
# If not running interactively, do not do anything
if command -v tmux>/dev/null; then
  [[ ! $TERM =~ screen ]] && [ -z $TMUX ] && exec tmux
fi

Auto attach

to automatically attach to last session or create a new if none available extend your ~/.bashrc and ~/.tmux.conf with the following

~/.bashrc

# Start Tmux by default
# If not running interactively, do not do anything
if command -v tmux>/dev/null; then
  [[ ! $TERM =~ screen ]] && [ -z $TMUX ] && exec tmux attach
fi

~/.tmux.conf

# if run as "tmux attach", create a session if one does not already exist
new-session -n $HOST

Continue reading Tmux on login

DNS Fun

calc

A calculator supporting addition, substraction, multiplication and division (respectively : ADD, SUB ,MUL, and DIV operations). More information here.

dig 2.8.add.calc.postel.org @dns.postel.org +short
0.10.0.0
dig 8.2.sub.calc.postel.org @dns.postel.org +short
0.6.0.0
dig 2.8.mul.calc.postel.org @dns.postel.org +short
0.16.0.0
dig 8.2.div.calc.postel.org @dns.postel.org +short
0.4.0.0

IP to ASN Mapping

A service providing a way to map IPv4 and IPv6 addresses or prefixs to ASNs, get information about ASNs, and even find possible peers. More details here.

Mapping an IP address or prefix to a corresponding BGP Origin ASN:

dig 4.4.8.8.origin.asn.cymru.com TXT +short
"15169 | 8.8.4.0/24 | US | arin |"
dig 4.8.8.origin.asn.cymru.com TXT +short
"15169 | 8.8.4.0/24 | US | arin |"
dig 4.4.8.8.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.6.8.4.0.6.8.4.1.0.0.2.origin6.asn.cymru.com TXT +short
"15169 | 2001:4860::/32 | US | arin | 2005-03-14"

Getting information about a given ASN:

dig AS15169.asn.cymru.com TXT +short
"15169 | US | arin | 2000-03-30 | GOOGLE - Google Inc.,US"

fun

dig any google-public-dns-a.google.com +noall +answer
; <<>> DiG 9.8.3-P1 <<>> any google-public-dns-a.google.com +noall +answer
;; global options: +cmd
google-public-dns-a.google.com.	38271 IN TXT	"http://xkcd.com/1361/"
google-public-dns-a.google.com.	38271 IN AAAA	2001:4860:4860::8888
google-public-dns-a.google.com.	38271 IN A	8.8.8.8

more stuff at http://www.cambus.net/interesting-dns-hacks/