maxmalysh / r0c

retr0chat telnet server

r0c telnet server

• retr0chat, irc-like chat service for superthin clients (on PyPI)
• MIT-Licensed, 2018-01-07, ed @ irc.rizon.net
• windows telnet 360 noscope <- good video

• download the latest release (standalone): r0c.py

summary

imagine being stuck on ancient gear, in the middle of nowhere, on a slow connection between machines that are even more archaic than the toaster you're trying to keep from falling apart

retr0chat is the lightweight, no-dependencies, runs-anywhere solution for when life gives you lemons

• tries to be irssi
• zero dependencies on python 2.6, 2.7, 3.x
• supports telnet, netcat, /dev/tcp clients
• fallbacks for inhumane conditions
  • linemode
  • no vt100 / ansi escape codes

windows clients

• use putty in telnet mode
• or the powershell client
• or enable Telnet Client in control panel -> programs -> programs and features -> turn windows features on or off, then press WIN+R and run telnet r0c.int

putty is the best option;

• windows-telnet has a bug (since win7) where unicode letters become unstable the more text you have on the screen (starts flickering and then disappear one by one)
• the powershell client is no longer spammy as of windows 10.0.15063 (win10 1703 / LTSC)

linux clients

most to least recommended

client	example
telnet	telnet r0c.int
socat	socat -,raw,echo=0 tcp:r0c.int:531
bash	mostly internals
netcat	nc r0c.int 531

you can even exec 147<>/dev/tcp/r0c.int/531;cat<&147&while IFS= read -rn1 x;do [ -z "$x" ]&&x=$'\n';printf %s "$x">&147;done (disconnect using exec 147<&-; killall cat #sorry)

firewall rules

telnet uses port 23 by default, so on the server you'll want to port-forward 23 to 2323 (and 531 to 1531 for plaintext):

iptables -A INPUT -p tcp --dport 23 -m state --state NEW -j ACCEPT
iptables -A INPUT -p tcp --dport 531 -m state --state NEW -j ACCEPT
iptables -A INPUT -p tcp --dport 2323 -m state --state NEW -j ACCEPT
iptables -A INPUT -p tcp --dport 1531 -m state --state NEW -j ACCEPT
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 23 -j REDIRECT --to-port 2323
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 531 -j REDIRECT --to-port 1531

documentation

not really but there is a list of commands and a list of hotkeys