Hi All, I am currently trying to port sshd and sftpserver to an embedded OS which is having a Single Monolith Process Space. Hence I have converted the whole openssh code re-entrant for the RTOS tasks. The re-entrant code is tested and is working under Linux. But once I started the sshd running on the target, it looks like the sshd sends the SSH_MSG_SERVICE_ACCEPT but is NOT received by the sftp client. Hence the client infinitely waits after sending SSH2_MSG_SERVICE_REQUEST and no further communication is happening. The sshd is in the select() loop as normal after sending the SSH_MSG_SERVICE_ACCEPT packet. It would be highly helpful if you could put some pointers to overcome this issue. Following is the client and server logs. sftp client log (Ubuntu) : http://pastebin.com/9697H7Y7 ... debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent sshd log (RTOS) : http://pastebin.com/3U3Mw2d9 ... I/O: debug2: set_newkeys: mode 1 I/O: debug2: cipher_init_context: 1 I/O: debug2: packet_send done I/O: debug2: SSH2_MSG_NEWKEYS sent I/O: debug2: expecting SSH2_MSG_NEWKEYS I/O: debug2: packet_read() I/O: debug2: input: packet len 16 I/O: debug2: partial packet: block 8, need 8, maclen 0, authlen 0, aadlen 0 I/O: read_poll enc/full: 0000 0000 0000 0000 I/O: debug2: input: padlen 10 I/O: debug2: input: len before de-compress 1 I/O: debug2: set_newkeys: mode 0 I/O: debug2: cipher_init_context: 0 I/O: read/plain[21]: I/O: I/O: debug2: received packet type 21 I/O: debug2: SSH2_MSG_NEWKEYS received I/O: debug2: KEX done I/O: debug2: packet_read() I/O: debug2: input: packet len 32 I/O: debug2: partial packet: block 16, need 16, maclen 16, authlen 0, aadlen 0 I/O: read_poll enc/full: 80e5 0ff5 e0c5 6f48 62cb 4383 6c43 2e98 I/O: b28a 3677 5765 5d81 fc18 b389 9f5d e203 I/O: I/O: debug2: MAC #4 ok I/O: debug2: input: padlen 10 I/O: debug2: input: len before de-compress 17 I/O: read/plain[5]: I/O: 0000 000c 7373 682d 7573 6572 6175 7468 I/O: I/O: debug2: received packet type 5 I/O: debug2: packet_start[6] I/O: plain: 0000 0000 0006 0000 000c 7373 682d 7573 I/O: 6572 6175 7468 I/O: debug2: send: len 32 (includes padlen 10, aadlen 0) I/O: debug2: done calc MAC out #4 I/O: encrypted: 77c1 c72a 976c 4e1e 0461 8a11 5391 9d0d I/O: d85d db30 73f1 0286 11a4 add3 8e07 4b5b I/O: I/O: debug2: packet_send done I/O: debug2: packet_read() Thanks, Shinose.