1 This is Dropbear, a smallish SSH 2 server and client. 2 3 INSTALL has compilation instructions. 4 5 MULTI has instructions on making a multi-purpose binary (ie a single binary 6 which performs multiple tasks, to save disk space) 7 8 SMALL has some tips on creating small binaries. 9 10 See TODO for a few of the things I know need looking at, and please contact 11 me if you have any questions/bugs found/features/ideas/comments etc :) 12 13 Matt Johnston 14 matt (a] ucc.asn.au 15 16 17 In the absence of detailed documentation, some notes follow: 18 ============================================================================ 19 20 Server public key auth: 21 22 You can use ~/.ssh/authorized_keys in the same way as with OpenSSH, just put 23 the key entries in that file. They should be of the form: 24 25 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAwVa6M6cGVmUcLl2cFzkxEoJd06Ub4bVDsYrWvXhvUV+ZAM9uGuewZBDoAqNKJxoIn0Hyd0Nk/yU99UVv6NWV/5YSHtnf35LKds56j7cuzoQpFIdjNwdxAN0PCET/MG8qyskG/2IE2DPNIaJ3Wy+Ws4IZEgdJgPlTYUBWWtCWOGc= someone@hostname 26 27 You must make sure that ~/.ssh, and the key file, are only writable by the 28 user. Beware of editors that split the key into multiple lines. 29 30 NOTE: Dropbear ignores authorized_keys options such as those described in the 31 OpenSSH sshd manpage, and will not allow a login for these keys. 32 33 ============================================================================ 34 35 Client public key auth: 36 37 Dropbear can do public key auth as a client, but you will have to convert 38 OpenSSH style keys to Dropbear format, or use dropbearkey to create them. 39 40 If you have an OpenSSH-style private key ~/.ssh/id_rsa, you need to do: 41 42 dropbearconvert openssh dropbear ~/.ssh/id_rsa ~/.ssh/id_rsa.db 43 dbclient -i ~/.ssh/id_rsa.db <hostname> 44 45 Currently encrypted keys aren't supported, neither is agent forwarding. At some 46 stage both hopefully will be. 47 48 ============================================================================ 49 50 If you want to get the public-key portion of a Dropbear private key, look at 51 dropbearkey's '-y' option. 52 53 ============================================================================ 54 55 To run the server, you need to generate server keys, this is one-off: 56 ./dropbearkey -t rsa -f dropbear_rsa_host_key 57 ./dropbearkey -t dss -f dropbear_dss_host_key 58 59 or alternatively convert OpenSSH keys to Dropbear: 60 ./dropbearconvert openssh dropbear /etc/ssh/ssh_host_dsa_key dropbear_dss_host_key 61 62 ============================================================================ 63 64 If the server is run as non-root, you most likely won't be able to allocate a 65 pty, and you cannot login as any user other than that running the daemon 66 (obviously). Shadow passwords will also be unusable as non-root. 67 68 ============================================================================ 69 70 The Dropbear distribution includes a standalone version of OpenSSH's scp 71 program. You can compile it with "make scp", you may want to change the path 72 of the ssh binary, specified by _PATH_SSH_PROGRAM in options.h . By default 73 the progress meter isn't compiled in to save space, you can enable it by 74 adding 'SCPPROGRESS=1' to the make commandline. 75
