Hi there I currently trying certificate based authentication with ssh and was successful with user authentication, but failed to configure host authentication. I have the newest and shiniest version: kb@kb-pc:~$ ssh -v OpenSSH_5.6p1, OpenSSL 0.9.8k 25 Mar 2009 Created a CA key: ssh-keygen -t dsa -f ca_root Signed the host key: ssh-keygen -s ca_root -I kb-pc -h /usr/local/etc/ssh_host_dsa_key.pub Added the certificate after the host key to /usr/local/etc/sshd_config: HostKey /usr/local/etc/ssh_host_dsa_key HostCertificate /usr/local/etc/ssh_host_dsa_key-cert.pub Added the CA public key to ~/.ssh/known_hosts: @cert-authority * ssh-dss AAAAB3NzaC1kc3MAA... and tried to log in: kb@kb-pc:~$ ssh -v root@localhost OpenSSH_5.6p1, OpenSSL 0.9.8k 25 Mar 2009 debug1: Reading configuration data /home/kb/.ssh/config debug1: Reading configuration data /usr/local/etc/ssh_config debug1: Applying options for * debug1: Connecting to localhost [::1] port 22. debug1: Connection established. debug1: identity file /home/kb/.ssh/id_rsa type -1 debug1: identity file /home/kb/.ssh/id_rsa-cert type -1 debug1: identity file /home/kb/.ssh/id_dsa type 2 debug1: ssh_dss_verify: signature correct debug1: identity file /home/kb/.ssh/id_dsa-cert type 4 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.6 debug1: match: OpenSSH_5.6 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.6 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY The authenticity of host 'localhost (::1)' can't be established. DSA key fingerprint is 96:2e:ae:c2:4a:b8:24:0d:ee:1d:18:73:29:ad:72:e8. Are you sure you want to continue connecting (yes/no)? Which was not the result I expected. do I miss something? strace /usr/local/sbin/sshd indicates that the cerificate is read: munmap(0xb774a000, 4096) = 0 open("/usr/local/etc/ssh_host_dsa_key-cert.pub", O_RDONLY|O_LARGEFILE) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=1454, ...}) = 0 read(3, "ssh-dss-cert-v01@xxxxxxxxxxx AAA"..., 1454) = 1454 close(3) = 0 open("/usr/local/etc/ssh_host_dsa_key-cert.pub", O_RDONLY|O_LARGEFILE) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=1454, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb774a000 read(3, "ssh-dss-cert-v01@xxxxxxxxxxx AAA"..., 4096) = 1454 read(3, "", 4096) = 0 close(3) = 0 munmap(0xb774a000, 4096) = 0 open("/usr/local/etc/ssh_host_dsa_key-cert.pub", O_RDONLY|O_LARGEFILE) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=1454, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb774a000 read(3, "ssh-dss-cert-v01@xxxxxxxxxxx AAA"..., 4096) = 1454 close(3) = 0 Any idea? Thanks and regards Konrad Bucheli -- konrad bucheli security engineer open systems ag raeffelstrasse 29 ch-8045 zurich t: +41 44 455 74 00 f: +41 44 455 74 01 kb@xxxxxxx http://www.open.ch