$ cat writeup.md…
$ cat writeup.md…
grodno_new_year_2026
Task: Custom TCP protocol challenge requiring a payload with MD5 hash computed from the TCP sequence number. Solution: Used Scapy raw sockets with a random ISN (not zero) to perform the TCP handshake, computed md5(str(seq) + "get_flag") for the data packet payload, and blocked kernel RST packets via iptables in Docker.
Permission denied (requires tier.pro)
Sign in with GitHub, Discord, or Google to continue. No email required.
$sign in$ grep --similar