Negotiation failed after updating version.

0 votes
asked May 19 by JP_Instech (130 points)

I have an issue where we updated our licensed version of Rebex from 3.0.6586.0 to 5.0.7800.0

after the update we started getting negotiation failed errors.
IE: Negotiation failed. The connection was closed by the server.

If we revert to the older version it works. ultimately we want it to work on the newer version for the security fixes, but will be forced to revert if we cannot solve this problem.

After searching your forum I have tried manipulating the KeyExchangeAlgorithms, PreferredHostKeyAlgorithm, and UseLegacyGroupExchange to see if that would resolve the problem but so far I've been working in the blind.

the code that works with 3.0.6586.0 has these settings:

_client.Settings.SshParameters.KeyExchangeAlgorithms |= SshKeyExchangeAlgorithm.DiffieHellmanGroup1SHA1;
_client.Settings.SshParameters.PreferredHostKeyAlgorithm = SshHostKeyAlgorithm.RSA;

I'll post the failure log in a reply as it is too long.

Applies to: Rebex SFTP
commented May 19 by JP_Instech (130 points)
2021-05-18 16:12:44.298 Opening log file.
2021-05-18 16:12:44.305 INFO FileLogWriter(1)[1] Info: Assembly: Rebex.Common R5.2 for .NET 4.6-4.8
2021-05-18 16:12:44.308 INFO FileLogWriter(1)[1] Info: Platform: Windows 6.2.9200 32-bit; CLR: 4.0.30319.42000
2021-05-18 16:12:44.310 DEBUG FileLogWriter(1)[1] Info: Culture: en; Windows-1252
2021-05-18 16:12:46.436 INFO Sftp(1)[1] Info: Connecting to 207.45.41.162:22 using Sftp.
2021-05-18 16:12:46.436 INFO Sftp(1)[1] Info: Assembly: Rebex.Sftp R5.2 for .NET 4.6-4.8
2021-05-18 16:12:46.438 INFO Sftp(1)[1] Info: Platform: Windows 6.2.9200 32-bit; CLR: 4.0.30319.42000
2021-05-18 16:12:46.438 DEBUG Sftp(1)[1] Info: Culture: en; Windows-1252
2021-05-18 16:12:46.511 DEBUG Sftp(1)[1] Proxy: Connecting to 207.45.41.162:22 (no proxy).
2021-05-18 16:12:46.587 DEBUG Sftp(1)[1] Proxy: Connection established.
2021-05-18 16:12:46.599 VERBOSE Sftp(1)[1] SSH: Sending data:
 0000 |53-53-48-2D-32-2E-30-2D 52-65-62-65-78-53-53-48| SSH-2.0-RebexSSH
 0010 |5F-35-2E-30-2E-37-38-30 30-2E-30-0D-0A         | _5.0.7800.0..
2021-05-18 16:12:46.790 VERBOSE Sftp(1)[1] SSH: Received data:
 0000 |53-53-48-2D-32-2E-30-2D 4F-70-65-6E-53-53-48-5F| SSH-2.0-OpenSSH_
 0010 |37-2E-36-0D-0A                                 | 7.6..
2021-05-18 16:12:46.791 DEBUG Sftp(1)[1] SSH: Server is 'SSH-2.0-OpenSSH_7.6'.
2021-05-18 16:12:46.801 INFO Sftp(1)[1] SSH: Negotiation started.
2021-05-18 16:12:46.816 VERBOSE Sftp(1)[7] SSH: Received packet SSH_MSG_KEXINIT (975 bytes).
 0000 |14-B5-72-05-09-43-1E-09 DB-4C-95-7C-C5-B9-93-3B| ..r..C...L.|...;
 0010 |4A-00-00-01-40-63-75-72 76-65-32-35-35-31-39-2D| J...@curve25519-
 0020 |73-68-61-32-35-36-2C-63 75-72-76-65-32-35-35-31| sha256,curve2551
 0030 |39-2D-73-68-61-32-35-36 40-6C-69-62-73-73-68-2E| 9-sha256@libssh.
 0040 |6F-72-67-2C-65-63-64-68 2D-73-68-61-32-2D-6E-69| org,ecdh-sha2-ni
 0050 |73-74-70-32-35-36-2C-65 63-64-68-2D-73-68-61-32| stp256,ecdh-sha2
 0060 |2D-6E-69-73-74-70-33-38 34-2C-65-63-64-68-2D-73| -nistp384,ecdh-s
 0070 |68-61-32-2D-6E-69-73-74 70-35-32-31-2C-64-69-66| ha2-nistp521,dif
 0080 |66-69-65-2D-68-65-6C-6C 6D-61-6E-2D-67-72-6F-75| fie-hellman-grou
 0090 |70-2D-65-78-63-68-61-6E 67-65-2D-73-68-61-32-35| p-exchange-sha25
 00A0 |36-2C-64-69-66-66-69-65 2D-68-65-6C-6C-6D-61-6E| 6,diffie-hellman
 00B0 |2D-67-72-6F-75-70-31-36 2D-73-68-61-35-31-32-2C| -group16-sha512,
 00C0 |64-69-66-66-69-65-2D-68 65-6C-6C-6D-61-6E-2D-67| diffie-hellman-g
 00D0 |72-6F-75-70-31-38-2D-73 68-61-35-31-32-2C-64-69| roup18-sha512,di
 00E0 |66-66-69-65-2D-68-65-6C 6C-6D-61-6E-2D-67-72-6F| ffie-hellman-gro
 00F0 |75-70-2D-65-78-63-68-61 6E-67-65-2D-73-68-61-31| up-exchange-sha1
 0100 |2C-64-69-66-66-69-65-2D 68-65-6C-6C-6D-61-6E-2D| ,diffie-hellman-
 0110 |67-72-6F-75-70-31-34-2D 73-68-61-32-35-36-2C-64| group14-sha256,d
 0120 |69-66-66-69-65-2D-68-65 6C-6C-6D-61-6E-2D-67-72| iffie-hellman-gr
 0130 |6F-75-70-31-34-2D-73-68 61-31-2C-64-69-66-66-69| oup14-sha1,diffi
 0140 |65-2D-68-65-6C-6C-6D-61 6E-2D-67-72-6F-75-70-31| e-hellman-group1
 0150 |2D-73-68-61-31-00-00-00 21-73-73-68-2D-72-73-61| -sha1...!ssh-rsa
 0160 |2C-72-73-61-2D-73-68-61 32-2D-35-31-32-2C-72-73| ,rsa-sha2-512,rs
 0170 |61-2D-73-68-61-32-2D-32 35-36-00-00-00-6F-61-65| a-sha2-256...oae
 0180 |73-31-32-38-2D-63-74-72 2C-61-65-73-31-39-32-2D| s128-ctr,aes192-
 0190 |63-74-72-2C-61-65-73-32 35-36-2D-63-74-72-2C-61| ctr,aes256-ctr,a
 01A0 |65-73-31-32-38-2D-63-62 63-2C-61-65-73-31-39-32| es128-cbc,aes192
 01B0 |2D-63-62-63-2C-61-65-73 32-35-36-2D-63-62-63-2C| -cbc,aes256-cbc,
 01C0 |61-65-73-32-35-36-2D-67 63-6D-40-6F-70-65-6E-73| aes256-gcm@opens
 01D0 |73-68-2E-63-6F-6D-2C-61 65-73-31-32-38-2D-67-63| sh.com,aes128-gc
 01E0 |6D-40-6F-70-65-6E-73-73 68-2E-63-6F-6D-00-00-00| m@openssh.com...
 01F0 |6F-61-65-73-31-32-38-2D 63-74-72-2C-61-65-73-31| oaes128-ctr,aes1
 0200 |39-32-2D-63-74-72-2C-61 65-73-32-35-36-2D-63-74| 92-ctr,aes256-ct
 0210 |72-2C-61-65-73-31-32-38 2D-63-62-63-2C-61-65-73| r,aes128-cbc,aes
 0220 |31-39-32-2D-63-62-63-2C 61-65-73-32-35-36-2D-63| 192-cbc,aes256-c
 0230 |62-63-2C-61-65-73-32-35 36-2D-67-63-6D-40-6F-70| bc,aes256-gcm@op
 0240 |65-6E-73-73-68-2E-63-6F 6D-2C-61-65-73-31-32-38| enssh.com,aes128
 0250 |2D-67-63-6D-40-6F-70-65 6E-73-73-68-2E-63-6F-6D| -gcm@openssh.com
 0260 |00-00-00-A5-68-6D-61-63 2D-73-68-61-31-2D-65-74| ....hmac-sha1-et
 0270 |6D-40-6F-70-65-6E-73-73 68-2E-63-6F-6D-2C-68-6D| m@openssh.com,hm
 0280 |61-63-2D-73-68-61-32-2D 32-35-36-2D-65-74-6D-40| ac-sha2-256-etm@
 0290 |6F-70-65-6E-73-73-68-2E 63-6F-6D-2C-68-6D-61-63| openssh.com,hmac
 02A0 |2D-73-68-61-32-2D-35-31 32-2D-65-74-6D-40-6F-70| -sha2-512-etm@op
 02B0 |65-6E-73-73-68-2E-63-6F 6D-2C-68-6D-61-63-2D-73| enssh.com,hmac-s
 02C0 |68-61-31-2D-39-36-2D-65 74-6D-40-6F-70-65-6E-73| ha1-96-etm@opens
 02D0 |73-68-2E-63-6F-6D-2C-68 6D-61-63-2D-73-68-61-31| sh.com,hmac-sha1
 02E0 |2C-68-6D-61-63-2D-73-68 61-32-2D-32-35-36-2C-68| ,hmac-sha2-256,h
 02F0 |6D-61-63-2D-73-68-61-32 2D-35-31-32-2C-68-6D-61| mac-sha2-512,hma
 0300 |63-2D-73-68-61-31-2D-39 36-00-00-00-A5-68-6D-61| c-sha1-96....hma
 0310 |63-2D-73-68-61-31-2D-65 74-6D-40-6F-70-65-6E-73| c-sha1-etm@opens
 0320 |73-68-2E-63-6F-6D-2C-68 6D-61-63-2D-73-68-61-32| sh.com,hmac-sha2
 0330 |2D-32-35-36-2D-65-74-6D 40-6F-70-65-6E-73-73-68| -256-etm@openssh
 0340 |2E-63-6F-6D-2C-68-6D-61 63-2D-73-68-61-32-2D-35| .com,hmac-sha2-5
 0350 |31-32-2D-65-74-6D-40-6F 70-65-6E-73-73-68-2E-63| 12-etm@openssh.c
 0360 |6F-6D-2C-68-6D-61-63-2D 73-68-61-31-2D-39-36-2D| om,hmac-sha1-96-
 0370 |65-74-6D-40-6F-70-65-6E 73-73-68-2E-63-6F-6D-2C| etm@openssh.com,
 0380 |68-6D-61-63-2D-73-68-61 31-2C-68-6D-61-63-2D-73| hmac-sha1,hmac-s
 0390 |68-61-32-2D-32-35-36-2C 68-6D-61-63-2D-73-68-61| ha2-256,hmac-sha
 03A0 |32-2D-35-31-32-2C-68-6D 61-63-2D-73-68-61-31-2D| 2-512,hmac-sha1-
 03B0 |39-36-00-00-00-04-6E-6F 6E-65-00-00-00-04-6E-6F| 96....none....no
 03C0 |6E-65-00-00-00-00-00-00 00-00-00-00-00-00-00   | ne.............
commented May 19 by JP_Instech (130 points)
2021-05-18 16:12:46.937 VERBOSE Sftp(1)[1] SSH: Sending packet SSH_MSG_KEXINIT (1282 bytes).
 0000 |14-DA-C5-A4-B2-CB-2F-18 31-C5-0F-5A-65-BF-14-C6| ....../.1..Ze...
 0010 |68-00-00-01-25-63-75-72 76-65-32-35-35-31-39-2D| h...%curve25519-
 0020 |73-68-61-32-35-36-2C-63 75-72-76-65-32-35-35-31| sha256,curve2551
 0030 |39-2D-73-68-61-32-35-36 40-6C-69-62-73-73-68-2E| 9-sha256@libssh.
 0040 |6F-72-67-2C-65-63-64-68 2D-73-68-61-32-2D-6E-69| org,ecdh-sha2-ni
 0050 |73-74-70-32-35-36-2C-64 69-66-66-69-65-2D-68-65| stp256,diffie-he
 0060 |6C-6C-6D-61-6E-2D-67-72 6F-75-70-2D-65-78-63-68| llman-group-exch
 0070 |61-6E-67-65-2D-73-68-61 32-35-36-2C-64-69-66-66| ange-sha256,diff
 0080 |69-65-2D-68-65-6C-6C-6D 61-6E-2D-67-72-6F-75-70| ie-hellman-group
 0090 |31-34-2D-73-68-61-32-35 36-2C-64-69-66-66-69-65| 14-sha256,diffie
 00A0 |2D-68-65-6C-6C-6D-61-6E 2D-67-72-6F-75-70-31-35| -hellman-group15
 00B0 |2D-73-68-61-35-31-32-2C 64-69-66-66-69-65-2D-68| -sha512,diffie-h
 00C0 |65-6C-6C-6D-61-6E-2D-67 72-6F-75-70-31-36-2D-73| ellman-group16-s
 00D0 |68-61-35-31-32-2C-64-69 66-66-69-65-2D-68-65-6C| ha512,diffie-hel
 00E0 |6C-6D-61-6E-2D-67-72-6F 75-70-2D-65-78-63-68-61| lman-group-excha
 00F0 |6E-67-65-2D-73-68-61-31 2C-64-69-66-66-69-65-2D| nge-sha1,diffie-
 0100 |68-65-6C-6C-6D-61-6E-2D 67-72-6F-75-70-31-34-2D| hellman-group14-
 0110 |73-68-61-31-2C-64-69-66 66-69-65-2D-68-65-6C-6C| sha1,diffie-hell
 0120 |6D-61-6E-2D-67-72-6F-75 70-31-2D-73-68-61-31-2C| man-group1-sha1,
 0130 |65-78-74-2D-69-6E-66-6F 2D-63-00-00-00-9F-72-73| ext-info-c....rs
 0140 |61-2D-73-68-61-32-2D-32 35-36-2C-73-73-68-2D-72| a-sha2-256,ssh-r
 0150 |73-61-2D-73-68-61-32-35 36-40-73-73-68-2E-63-6F| sa-sha256@ssh.co
 0160 |6D-2C-72-73-61-2D-73-68 61-32-2D-35-31-32-2C-73| m,rsa-sha2-512,s
 0170 |73-68-2D-72-73-61-2C-73 73-68-2D-64-73-73-2C-78| sh-rsa,ssh-dss,x
 0180 |35-30-39-76-33-2D-73-69 67-6E-2D-72-73-61-2D-73| 509v3-sign-rsa-s
 0190 |68-61-32-35-36-40-73-73 68-2E-63-6F-6D-2C-78-35| ha256@ssh.com,x5
 01A0 |30-39-76-33-2D-73-69-67 6E-2D-72-73-61-2C-78-35| 09v3-sign-rsa,x5
 01B0 |30-39-76-33-2D-73-69-67 6E-2D-64-73-73-2C-73-73| 09v3-sign-dss,ss
 01C0 |68-2D-65-64-32-35-35-31 39-2C-65-63-64-73-61-2D| h-ed25519,ecdsa-
 01D0 |73-68-61-32-2D-6E-69-73 74-70-32-35-36-00-00-01| sha2-nistp256...
 01E0 |05-61-65-73-32-35-36-2D 67-63-6D-40-6F-70-65-6E| .aes256-gcm@open
 01F0 |73-73-68-2E-63-6F-6D-2C 61-65-73-31-32-38-2D-67| ssh.com,aes128-g
 0200 |63-6D-40-6F-70-65-6E-73 73-68-2E-63-6F-6D-2C-61| cm@openssh.com,a
 0210 |65-73-32-35-36-2D-63-74 72-2C-61-65-73-31-39-32| es256-ctr,aes192
 0220 |2D-63-74-72-2C-61-65-73 31-32-38-2D-63-74-72-2C| -ctr,aes128-ctr,
 0230 |33-64-65-73-2D-63-74-72 2C-74-77-6F-66-69-73-68| 3des-ctr,twofish
 0240 |32-35-36-2D-63-74-72-2C 74-77-6F-66-69-73-68-31| 256-ctr,twofish1
 0250 |39-32-2D-63-74-72-2C-74 77-6F-66-69-73-68-31-32| 92-ctr,twofish12
 0260 |38-2D-63-74-72-2C-61-65 73-32-35-36-2D-63-62-63| 8-ctr,aes256-cbc
 0270 |2C-61-65-73-31-39-32-2D 63-62-63-2C-61-65-73-31| ,aes192-cbc,aes1
 0280 |32-38-2D-63-62-63-2C-33 64-65-73-2D-63-62-63-2C| 28-cbc,3des-cbc,
 0290 |74-77-6F-66-69-73-68-32 35-36-2D-63-62-63-2C-74| twofish256-cbc,t
 02A0 |77-6F-66-69-73-68-31-39 32-2D-63-62-63-2C-74-77| wofish192-cbc,tw
 02B0 |6F-66-69-73-68-31-32-38 2D-63-62-63-2C-74-77-6F| ofish128-cbc,two
 02C0 |66-69-73-68-2D-63-62-63 2C-63-68-61-63-68-61-32| fish-cbc,chacha2
 02D0 |30-2D-70-6F-6C-79-31-33 30-35-40-6F-70-65-6E-73| 0-poly1305@opens
 02E0 |73-68-2E-63-6F-6D-00-00 01-05-61-65-73-32-35-36| sh.com....aes256
 02F0 |2D-67-63-6D-40-6F-70-65 6E-73-73-68-2E-63-6F-6D| -gcm@openssh.com
 0300 |2C-61-65-73-31-32-38-2D 67-63-6D-40-6F-70-65-6E| ,aes128-gcm@open
 0310 |73-73-68-2E-63-6F-6D-2C 61-65-73-32-35-36-2D-63| ssh.com,aes256-c
 0320 |74-72-2C-61-65-73-31-39 32-2D-63-74-72-2C-61-65| tr,aes192-ctr,ae
 0330 |73-31-32-38-2D-63-74-72 2C-33-64-65-73-2D-63-74| s128-ctr,3des-ct
 0340 |72-2C-74-77-6F-66-69-73 68-32-35-36-2D-63-74-72| r,twofish256-ctr
 0350 |2C-74-77-6F-66-69-73-68 31-39-32-2D-63-74-72-2C| ,twofish192-ctr,
 0360 |74-77-6F-66-69-73-68-31 32-38-2D-63-74-72-2C-61| twofish128-ctr,a
 0370 |65-73-32-35-36-2D-63-62 63-2C-61-65-73-31-39-32| es256-cbc,aes192
 0380 |2D-63-62-63-2C-61-65-73 31-32-38-2D-63-62-63-2C| -cbc,aes128-cbc,
 0390 |33-64-65-73-2D-63-62-63 2C-74-77-6F-66-69-73-68| 3des-cbc,twofish
 03A0 |32-35-36-2D-63-62-63-2C 74-77-6F-66-69-73-68-31| 256-cbc,twofish1
 03B0 |39-32-2D-63-62-63-2C-74 77-6F-66-69-73-68-31-32| 92-cbc,twofish12
 03C0 |38-2D-63-62-63-2C-74-77 6F-66-69-73-68-2D-63-62| 8-cbc,twofish-cb
 03D0 |63-2C-63-68-61-63-68-61 32-30-2D-70-6F-6C-79-31| c,chacha20-poly1
 03E0 |33-30-35-40-6F-70-65-6E 73-73-68-2E-63-6F-6D-00| 305@openssh.com.
 03F0 |00-00-61-68-6D-61-63-2D 73-68-61-32-2D-32-35-36| ..ahmac-sha2-256
 0400 |2D-65-74-6D-40-6F-70-65 6E-73-73-68-2E-63-6F-6D| -etm@openssh.com
 0410 |2C-68-6D-61-63-2D-73-68 61-32-2D-32-35-36-2C-68| ,hmac-sha2-256,h
 0420 |6D-61-63-2D-73-68-61-32 2D-35-31-32-2D-65-74-6D| mac-sha2-512-etm
 0430 |40-6F-70-65-6E-73-73-68 2E-63-6F-6D-2C-68-6D-61| @openssh.com,hma
 0440 |63-2D-73-68-61-32-2D-35 31-32-2C-68-6D-61-63-2D| c-sha2-512,hmac-
 0450 |73-68-61-31-00-00-00-61 68-6D-61-63-2D-73-68-61| sha1...ahmac-sha
 0460 |32-2D-32-35-36-2D-65-74 6D-40-6F-70-65-6E-73-73| 2-256-etm@openss
 0470 |68-2E-63-6F-6D-2C-68-6D 61-63-2D-73-68-61-32-2D| h.com,hmac-sha2-
 0480 |32-35-36-2C-68-6D-61-63 2D-73-68-61-32-2D-35-31| 256,hmac-sha2-51
 0490 |32-2D-65-74-6D-40-6F-70 65-6E-73-73-68-2E-63-6F| 2-etm@openssh.co
 04A0 |6D-2C-68-6D-61-63-2D-73 68-61-32-2D-35-31-32-2C| m,hmac-sha2-512,
 04B0 |68-6D-61-63-2D-73-68-61 31-00-00-00-1A-6E-6F-6E| hmac-sha1....non
 04C0 |65-2C-7A-6C-69-62-2C-7A 6C-69-62-40-6F-70-65-6E| e,zlib,zlib@open
 04D0 |73-73-68-2E-63-6F-6D-00 00-00-1A-6E-6F-6E-65-2C| ssh.com....none,
 04E0 |7A-6C-69-62-2C-7A-6C-69 62-40-6F-70-65-6E-73-73| zlib,zlib@openss
 04F0 |68-2E-63-6F-6D-00-00-00 00-00-00-00-00-00-00-00| h.com...........
 0500 |00-00                                          | ..
2021-05-18 16:12:46.951 DEBUG Sftp(1)[1] SSH: Negotiating key.
2021-05-18 16:12:46.959 VERBOSE Sftp(1)[1] SSH: Sending packet SSH_MSG_KEX_30 (37 bytes).
 0000 |1E-00-00-00-20-1D-F6-B6 CC-C4-B6-5A-74-70-71-85| .... ......Ztpq.
 0010 |B7-44-8B-14-88-3A-00-3B DB-ED-06-48-6F-98-F3-2E| .D...:.;...Ho...
 0020 |FE-CF-2B-6D-2A                                 | ..+m*
2021-05-18 16:12:47.015 DEBUG Sftp(1)[7] SSH: SSH connection closed.
2021-05-18 16:12:47.020 ERROR Sftp(1)[1] SSH: Negotiation failed. The connection was closed by the server.
2021-05-18 16:12:47.028 ERROR Sftp(1)[1] Info: Rebex.Net.SshException: The connection was closed by the server.
   at Rebex.Net.SshSession.zdtde[T,S](nryaa`2 p0, Int32 p1, wvmhp p2, S p3, T p4, T p5)
   at Rebex.Net.SshSession.yntgu[T,S](nryaa`2 p0, S p1)
   at Rebex.Net.SshSession.fdetz(wjwzv p0)
   at fbmqn.yuozn.acyly(SshSession p0, Byte[] p1, Byte[] p2, Byte[] p3, Byte[] p4, vuqti& p5, Byte[]& p6, SshPublicKey& p7)
   at Rebex.Net.SshSession.dgduw(Byte[] p0)
   at Rebex.Net.SshSession.Negotiate()
   at Rebex.Net.Sftp.fbmqn.mjgdl.gmlbl(rqghl p0, Boolean p1)
   at Rebex.Net.Sftp.yhxos(String p0, Int32 p1, SshParameters p2, rqghl p3)

1 Answer

+1 vote
answered May 19 by Lukas Pokorny (123,150 points)

This looks like Curve25519 key exchange cipher might be to blame, although it's a bit strange, because we are currently not aware of any incompatibility between Rebex SFTP and OpenSSH 7.6. Please try disabling this cipher and let us know whether that helps:

_client.Settings.SshParameters.KeyExchangeAlgorithms &=
~SshKeyExchangeAlgorithm.Curve25519;

On an unrelated note: unless you really need DiffieHellmanGroup1SHA1 and accept its risks, it's recommended not to enable that cipher because it is considered vulnerable to state-level adversaries.

commented May 19 by JP_Instech (130 points)
edited May 19 by JP_Instech
Thanks for your time on this. I've discussed this with the relevant people and the best access we could give you is to do a live session where I share the screen of the machine that has connectivity and we interactively go from there. Also if there are other tools like network sniffers that would give you more relevant information we can go down that route.  if that would be useful let me know. If we can continue this with email that would be great as I would prefer to discuss this on something other then a public forum due to security concerns.

Thanks.
commented May 19 by Lukas Pokorny (123,150 points)
OK, in that case, let's first try configuring v5.0.7800.0 to send SSH_MSG_KEXINIT identical to that of v3.0.6586.0 tomorrow (I'll send you an email with relevant code from support@rebex.net and notify you here as well), and if that doesn't get us closer to a solution, we'll try the live session later.
commented May 20 by Lukas Pokorny (123,150 points)
I just sent you an e-mail with instructions. Please give it a try and let me know whether that works around the issue.
commented May 20 by JP_Instech (130 points)
Thanks the specific configuration you provided fixed the issue. I did not have to resort to using the hotfix.
Thanks for the really great and responsive support.
commented May 21 by Lukas Pokorny (123,150 points)
Thanks for letting us know!
Still, it might be useful to know which particular setting triggers the issue. Would it be possible to try removing those 7 settings one-by-one to find out which ones are actually necessary to work around the problem? Let me know by e-mail if you prefer.
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