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

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 wastes a LOT of data (an entire kilobyte for each new message, totally unbelievable, who could possibly afford that) because powershell's scrolling is glitchy af

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