如何编写简单的SSH客户端？

Question

我打算在C/C++中为我的介绍网络类中的项目编写一个简单的SSH客户端。然而，我在寻找关于如何做到这一点的良好文档方面遇到了麻烦。我不想要广泛的协议规范，只是一个简单的指南。有什么建议么？

Answer 1

我想借此看看libssl和libcrypto库，是OpenSSL project的一部分。在基于Debian的系统，你可以使用得到开发库：

sudo apt-get install libssl-dev 

我想看看文件下/usr/share/doc/libssl-dev/demos

编辑：另外，您也read the documentation here或安装后，运行man ssl

Answer 2

步骤：

1. 获得一个现有的服务器端实例凭证
2. 安装一个开源客户
3. 上执行命令行
4. 包括CLI，用于开关一个连接详细日志
5. 使用日志来推断在双方同意的密码实现上获取经过验证的会话时涉及的来回（C/S协议）消息。

标准输出：

$ ssh -vvv myhost.com 
OpenSSH_5.9p1, OpenSSL 0.9.8t 18 Jan 2012 
debug1: Reading configuration data /home/myself/.ssh/config 
debug2: ssh_connect: needpriv 0 
debug1: Connecting to myhost.com [74.99.99.99] port 22. 
debug1: Connection established. 
debug3: Incorrect RSA1 identifier 
debug3: Could not load "/home/myself/.ssh/id_rsa" as a RSA1 public key 
debug1: identity file /home/myself/.ssh/id_rsa type 1 
debug1: identity file /home/myself/.ssh/id_rsa-cert type -1 
debug3: Incorrect RSA1 identifier 
debug3: Could not load "/home/myself/.ssh/id_dsa" as a RSA1 public key 
debug1: identity file /home/myself/.ssh/id_dsa type 2 
debug1: identity file /home/myself/.ssh/id_dsa-cert type -1 
debug1: identity file /home/myself/.ssh/id_ecdsa type -1 
debug1: identity file /home/myself/.ssh/id_ecdsa-cert type -1 
debug1: Remote protocol version 2.0, remote software version OpenSSH_3.5p1 
debug1: match: OpenSSH_3.5p1 pat OpenSSH_3.* 
debug1: Enabling compatibility mode for protocol 2.0 
debug1: Local version string SSH-2.0-OpenSSH_5.9 
debug2: fd 3 setting O_NONBLOCK 
debug3: load_hostkeys: loading entries for host "myhost.com" from file "/home/myself/.ssh/known_hosts" 
debug3: load_hostkeys: found key type RSA in file /home/myself/.ssh/known_hosts:12 
debug3: load_hostkeys: loaded 1 keys 
debug3: order_hostkeyalgs: prefer hostkeyalgs: ssh-rsa-cert-v01@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-rsa 
debug1: SSH2_MSG_KEXINIT sent 
debug1: SSH2_MSG_KEXINIT received 
debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diff 
ie-hellman-group14-sha1,diffie-hellman-group1-sha1 
debug2: kex_parse_kexinit: ssh-rsa-cert-v01@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-rsa,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v 
01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,ssh-dss-cert-v00@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa- 
sha2-nistp521,ssh-dss 
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rij 
ndael-cbc@lysator.liu.se 
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rij 
ndael-cbc@lysator.liu.se 
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,hmac-ripemd160@op 
enssh.com,hmac-sha1-96,hmac-md5-96 
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,hmac-ripemd160@op 
enssh.com,hmac-sha1-96,hmac-md5-96 
debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib 
debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1 
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss 
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se 
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se 
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 
debug2: kex_parse_kexinit: none,zlib 
debug2: kex_parse_kexinit: none,zlib 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: mac_setup: found hmac-md5 
debug1: kex: server->client aes128-cbc hmac-md5 none 
debug2: mac_setup: found hmac-md5 
debug1: kex: client->server aes128-cbc hmac-md5 none 
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent 
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP 
debug2: dh_gen_key: priv key bits set: 124/256 
debug2: bits set: 510/1024 
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent 
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY 
debug1: Server host key: RSA ac:24:92:03:fd:24:f8:01:a6:86:2a:bf:37:e9:a8:fe 
debug3: load_hostkeys: loading entries for host "myhost.com" from file "/home/myself/.ssh/known_hosts" 
debug3: load_hostkeys: found key type RSA in file /home/myself/.ssh/known_hosts:12 
debug3: load_hostkeys: loaded 1 keys 
debug3: load_hostkeys: loading entries for host "74.99.99.99" from file "/home/myself/.ssh/known_hosts" 
debug3: load_hostkeys: found key type RSA in file /home/myself/.ssh/known_hosts:25 
debug3: load_hostkeys: loaded 1 keys 
debug1: Host 'myhost.com' is known and matches the RSA host key. 
debug1: Found key in /home/myself/.ssh/known_hosts:12 
debug2: bits set: 532/1024 
debug1: ssh_rsa_verify: signature correct 
debug2: kex_derive_keys 
debug2: set_newkeys: mode 1 
debug1: SSH2_MSG_NEWKEYS sent 
debug1: expecting SSH2_MSG_NEWKEYS 
debug2: set_newkeys: mode 0 
debug1: SSH2_MSG_NEWKEYS received 
debug1: Roaming not allowed by server 
debug1: SSH2_MSG_SERVICE_REQUEST sent 
debug2: service_accept: ssh-userauth 
debug1: SSH2_MSG_SERVICE_ACCEPT received 
debug2: key: /home/myself/.ssh/id_rsa (0x800471d8) 
debug2: key: /home/myself/.ssh/id_dsa (0x80048380) 
debug2: key: /home/myself/.ssh/id_ecdsa (0x0) 
debug3: input_userauth_banner 

debug1: Authentications that can continue: publickey,password 
debug3: start over, passed a different list publickey,password 
debug3: preferred 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: Offering RSA public key: /home/myself/.ssh/id_rsa 
debug3: send_pubkey_test 
debug2: we sent a publickey packet, wait for reply 
debug1: Authentications that can continue: publickey,password 
debug1: Offering DSA public key: /home/myself/.ssh/id_dsa 
debug3: send_pubkey_test 
debug2: we sent a publickey packet, wait for reply 
debug1: Server accepts key: pkalg ssh-dss blen 433 
debug2: input_userauth_pk_ok: fp 15:6c:78:1e:76:02:03:26:2e:53:1a:44:8e:59:97:b1 
debug3: sign_and_send_pubkey: DSA 15:6c:78:1e:76:02:03:26:2e:53:1a:44:8e:59:97:b1 
debug1: read PEM private key done: type DSA 
debug1: Authentication succeeded (publickey). 
Authenticated to myhost.com ([74.99.99.99]:22). 
debug1: channel 0: new [client-session] 
debug3: ssh_session2_open: channel_new: 0 
debug2: channel 0: send open 
debug1: Entering interactive session. 
debug2: callback start 
debug2: client_session2_setup: id 0 
debug2: fd 3 setting TCP_NODELAY 
debug2: channel 0: request pty-req confirm 1 
debug2: channel 0: request shell confirm 1 
debug2: callback done 
debug2: channel 0: open confirm rwindow 0 rmax 32768 
debug2: channel_input_status_confirm: type 99 id 0 
debug2: PTY allocation request accepted on channel 0 
debug2: channel 0: rcvd adjust 131072 
debug2: channel_input_status_confirm: type 99 id 0 
debug2: shell request accepted on channel 0