Hi, I have a very strange ssh issue, and I do not know how to solve it. I have a centos VM (managed by libvirt) running the latest centos 7 and latest openssh server package (debug1: sshd version OpenSSH_7.4, OpenSSL 1.0.2k-fips 26 Jan 2017). When I ssh remotely to this centos VM (using latest putty 0.70 and other ssh clients as well), I do not get a login prompt whatsoever. I used openssh-server in debug mode, to see where the ssh connection hangs, and here is what I get: [root@centos1 ~]# /sbin/sshd -p 22 -D -d -e debug1: sshd version OpenSSH_7.4, OpenSSL 1.0.2k-fips 26 Jan 2017 debug1: private host key #0: ssh-rsa SHA256:pEuFQsodwK+0PoRzbVRba1ahHLEpwp8DG2KGQmxOGJk debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:F6HrSNWZhYaU7LMweI+RBviqTCHcTYyMBGPDz5OjT4c debug1: private host key #2: ssh-ed25519 SHA256:aG3V6jjPHXUnNeavbxT/xozqrb5q3yWDkkAmXBCdnGk debug1: rexec_argv[0]='/sbin/sshd' debug1: rexec_argv[1]='-p' debug1: rexec_argv[2]='22' debug1: rexec_argv[3]='-D' debug1: rexec_argv[4]='-d' debug1: rexec_argv[5]='-e' debug1: Set /proc/self/oom_score_adj from 0 to -1000 debug1: Bind to port 22 on 0.0.0.0. Server listening on 0.0.0.0 port 22. debug1: Bind to port 22 on ::. Server listening on :: port 22. Here the debug log stops and the openssh server waits for an inbound ssh client connection. At this stage I am using Putty v0.70 with all default settings to connect to this openssh sever, and below is the debug log after Putty starts the ssh connection: debug1: Server will not fork when running in debugging mode. debug1: rexec start in 5 out 5 newsock 5 pipe -1 sock 8 debug1: sshd version OpenSSH_7.4, OpenSSL 1.0.2k-fips 26 Jan 2017 debug1: private host key #0: ssh-rsa SHA256:pEuFQsodwK+0PoRzbVRba1ahHLEpwp8DG2KGQmxOGJk debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:F6HrSNWZhYaU7LMweI+RBviqTCHcTYyMBGPDz5OjT4c debug1: private host key #2: ssh-ed25519 SHA256:aG3V6jjPHXUnNeavbxT/xozqrb5q3yWDkkAmXBCdnGk debug1: inetd sockets after dupping: 3, 3 Connection from x.x.x.181 port 49436 on x.x.x.115 port 22 debug1: Client protocol version 2.0; client software version PuTTY_Release_0.70 debug1: no match: PuTTY_Release_0.70 debug1: Local version string SSH-2.0-OpenSSH_7.4 debug1: Enabling compatibility mode for protocol 2.0 debug1: SELinux support enabled [preauth] debug1: permanently_set_uid: 74/74 [preauth] debug1: list_hostkey_types: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 [preauth] debug1: SSH2_MSG_KEXINIT sent [preauth] Here the debug mode stops, and there is no login prompt shown on the Putty window. Actually nothing happens on the Putty window or in the openssh-server side, even if I wait for couple of minutes. Finally when I give up and I close the Putty window, this is what is shown in the openssh server debug log: Connection closed by x.x.x.181 port 49436 [preauth] debug1: do_cleanup [preauth] debug1: monitor_read_log: child log fd closed debug1: do_cleanup debug1: Killing privsep child 1274 I used the log in Putty side to see whats happening, and this is all what I get: =~=~=~=~=~=~=~=~=~=~=~= PuTTY log 2018.01.22 18:51:38 =~=~=~=~=~=~=~=~=~=~=~= Event Log: Writing new session log (SSH packets mode) to file: C:\Users\adrian\Desktop\putty.log Event Log: Connecting to x.x.x.115 port 22 Event Log: We claim version: SSH-2.0-PuTTY_Release_0.70 I have tried with other ssh clients as well, like MobaXterm (OpenSSH_7.1p2, OpenSSL 1.0.1g 7 Apr 2014), and the debug log in this ssh client side is the following: [2018-01-25 19:41.04] ~ # ssh -vvv x.x.x.115 OpenSSH_7.1p2, OpenSSL 1.0.1g 7 Apr 2014 debug1: Reading configuration data /etc/ssh_config debug2: ssh_connect: needpriv 0 debug1: Connecting to x.x.x.115 [x.x.x.115] port 22. debug1: Connection established. debug1: key_load_public: No such file or directory debug1: identity file /home/mobaxterm/.ssh/id_rsa type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/mobaxterm/.ssh/id_rsa-cert type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/mobaxterm/.ssh/id_dsa type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/mobaxterm/.ssh/id_dsa-cert type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/mobaxterm/.ssh/id_ecdsa type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/mobaxterm/.ssh/id_ecdsa-cert type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/mobaxterm/.ssh/id_ed25519 type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/mobaxterm/.ssh/id_ed25519-cert type -1 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_7.1 debug1: ssh_exchange_identification: debug1: ssh_exchange_identification: debug1: ssh_exchange_identification: \024\324C9\0047\311'\316h\340.\365\213J\243d debug1: ssh_exchange_identification: 1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug1: ssh_exchange_identification: @openssh.com,aes128-cbc,aes192-cbc,aes256-cbc,blowfish-cbc,cast128-cbc,3des-cbc debug1: ssh_exchange_identification: cbc debug1: ssh_exchange_identification: 8-etm@xxxxxxxxxxx,hmac-sha2-256-etm@xxxxxxxxxxx,hmac-sha2-512-etm@xxxxxxxxxxx,hmac-sha1-etm@xxxxxxxxxxx,umac-64@xxxxxxxxxxx,umac-128@xxxxxxxxxxx,hmac-sha2-256,hmac-sha2-512,hmac-sha1 Here the debug log stops, and I do not get an login prompt whatsoever. This is the first time I see this kind of issue, and I do not have any idea how to troubleshoot it further, therefore any suggestion would really be appreciated. Many thanks, Adrian _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
