RFC 4345 specifies two modes of operation for using the arcfour stream cipher in the secure shell (SSH) protocol. Even at the time of publication, there were known weaknesses in the arcfour keystream; the extent and exploitability of such weaknesses has increased with time, to the extent that the arcfour ciphers should not be used anymore, as discussed in draft-ietf-curdle-rc4-die-die-die. Accordingly, RFC 4345 is moved to historic.