2

I have a jumpbox server for SSH with an external IP that has DNS match with a wildcard – i.e., any address with the structure *.mydomain.com will result in the same IP address, which is the jumpbox IP.

What I'm attempting to do is to relay the connection to internal machines with a matching rule with User and Host criteria.

So far I succeeded doing so with a User criterion – i.e., ssh to the jumpbox will relay the connection to my internal machine when using a certain user.

The Match rule looks like below:

Match User myuser
  ForceCommand ssh -i /home/someuser/.ssh/global-rsa myuser@internalmachine $SSH_ORIGINAL_COMMAND

This works great when the user is doing ssh [email protected], but when I add Host to it:

Match User myuser Host usermachine.dev1.mydomain.com
  ForceCommand ssh -i /home/myuser/.ssh/global-rsa myuser@internalmachine $SSH_ORIGINAL_COMMAND

it completely ignores the matching rule.

The idea is to have this user routed to the specific machine it asked for and not to use different usernames for each machine for it.

After adding: UseDNS yes, when I do ssh [email protected] -vvv, I get:

OpenSSH_7.4p1 Debian-10+deb9u6, OpenSSL 1.0.2r  26 Feb 2019
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "usermachine.dev1.mydomain.com" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to usermachine.dev1.mydomain.com [xx.xx.xx.xx] port 22.
debug1: Connection established.
debug1: key_load_public: No such file or directory
debug1: identity file /home/myuser/.ssh/id_rsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/myuser/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/myuser/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/myuser/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/myuser/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/myuser/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/myuser/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/myuser/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.4p1 Debian-10+deb9u6
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.4p1 Debian-10+deb9u6
debug1: match: OpenSSH_7.4p1 Debian-10+deb9u6 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to usermachine.dev1.mydomain.com:22 as 'myuser'
debug3: hostkeys_foreach: reading file "/home/myuser/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/myuser/.ssh/known_hosts:3
debug3: load_hostkeys: loaded 1 keys from usermachine.dev1.mydomain.com
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected],aes128-cbc,aes192-cbc,aes256-cbc
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected],aes128-cbc,aes192-cbc,aes256-cbc
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected],zlib
debug2: compression stoc: none,[email protected],zlib
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1
debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected]
debug2: compression stoc: none,[email protected]
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:eqPQ2fPZ9tVXyJ2me5VdBaHPHI9avXYUJjIETGmFTlM
debug3: hostkeys_foreach: reading file "/home/myuser/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/myuser/.ssh/known_hosts:3
debug3: load_hostkeys: loaded 1 keys from usermachine.dev1.mydomain.com
debug3: hostkeys_foreach: reading file "/home/myuser/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/myuser/.ssh/known_hosts:4
debug3: load_hostkeys: loaded 1 keys from xx.xx.xx.xx
debug1: Host 'usermachine.dev1.mydomain.com' is known and matches the ECDSA host key.
debug1: Found key in /home/myuser/.ssh/known_hosts:3
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug2: key: /home/myuser/.ssh/id_rsa ((nil))
debug2: key: /home/myuser/.ssh/id_dsa ((nil))
debug2: key: /home/myuser/.ssh/id_ecdsa ((nil))
debug2: key: /home/myuser/.ssh/id_ed25519 ((nil))
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,password
debug3: start over, passed a different list publickey,password
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /home/myuser/.ssh/id_rsa
debug3: no such identity: /home/myuser/.ssh/id_rsa: No such file or directory
debug1: Trying private key: /home/myuser/.ssh/id_dsa
debug3: no such identity: /home/myuser/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/myuser/.ssh/id_ecdsa
debug3: no such identity: /home/myuser/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/myuser/.ssh/id_ed25519
debug3: no such identity: /home/myuser/.ssh/id_ed25519: No such file or directory
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
[email protected]'s password:
debug3: send packet: type 50
debug2: we sent a password packet, wait for reply
debug3: receive packet: type 52
debug1: Authentication succeeded (password).
Authenticated to usermachine.dev1.mydomain.com ([xx.xx.xx.xx]:22).
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug3: send packet: type 90
debug1: Requesting [email protected]
debug3: send packet: type 80
debug1: Entering interactive session.
debug1: pledge: network
debug3: receive packet: type 80
debug1: client_input_global_request: rtype [email protected] want_reply 0
debug3: receive packet: type 91
debug2: callback start
debug2: fd 3 setting TCP_NODELAY
debug3: ssh_packet_set_tos: set IP_TOS 0x10
debug2: client_session2_setup: id 0
debug2: channel 0: request pty-req confirm 1
debug3: send packet: type 98
debug1: Sending environment.
debug3: Ignored env LS_COLORS
debug3: Ignored env SSH_CONNECTION
debug1: Sending env LANG = en_US.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env USER
debug3: Ignored env PWD
debug3: Ignored env HOME
debug3: Ignored env SSH_CLIENT
debug3: Ignored env SSH_TTY
debug3: Ignored env MAIL
debug3: Ignored env TERM
debug3: Ignored env SHELL
debug3: Ignored env SHLVL
debug3: Ignored env LOGNAME
debug3: Ignored env PATH
debug3: Ignored env _
debug2: channel 0: request shell confirm 1
debug3: send packet: type 98
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug3: receive packet: type 99
debug2: channel_input_status_confirm: type 99 id 0
debug2: PTY allocation request accepted on channel 0
debug2: channel 0: rcvd adjust 2097152
debug3: receive packet: type 99
debug2: channel_input_status_confirm: type 99 id 0
debug2: shell request accepted on channel 0
Linux jumpbox-6ff6b97487-6x5mg 4.14.89+ #1 SMP Wed Jan 9 13:35:00 PST 2019 x86_64

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Wed Apr 10 12:35:19 2019 from 10.16.0.110
myuser@jumpbox-6ff6b97487-6x5mg:~$
9
  • Does it work when the IP address is used instead of the FQDN? Commented Apr 10, 2019 at 11:34
  • That will miss the purpose since the IP is the same for ALL host names with that structure
    – Itai Malek
    Commented Apr 10, 2019 at 11:37
  • UseDNS ... If this option is set to no (the default) then only addresses and not host names may be used in ~/.ssh/authorized_keys from and sshd_config Match Host directives. Commented Apr 10, 2019 at 11:44
  • Please add the output of ssh [email protected] -vvv there should be the lines: debug3: /home/user/.ssh/config line 4: matched 'User "otheruser"' and debug3: /home/user/.ssh/config line 4: matched 'Host "test.mydomain.com"'.
    – ctx
    Commented Apr 10, 2019 at 11:55
  • I added the -vvv output to the question
    – Itai Malek
    Commented Apr 10, 2019 at 12:42

2 Answers 2

1

yes, there is, try to use syntax like this:

Host usermachine.dev1.mydomain.com
    Match User myuser
        ForceCommand ssh -i /home/myuser/.ssh/global-rsa myuser@internalmachine $SSH_ORIGINAL_COMMAND
0
0

I think this is the same question

https://serverfault.com/questions/34552/is-there-a-name-based-virtual-host-ssh-reverse-proxy

Short answer is no.

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