使用ssh时，把命令与登录拼在一起时，完成密码认证后，会报错“exec request failed on channel 0”。以下贴出debug.注意看最后，报出错误
ssh -v username@172.16.0.1 "dis cu"
[root@app1 ~]# ssh -v username@172.16.0.1 dir
OpenSSH_8.5p1, OpenSSL 1.0.2s 28 May 2019
debug1: Reading configuration data /root/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling
debug1: Connecting to 172.16.0.1 [172.16.0.1] port 22.
debug1: Connection established.
debug1: identity file /root/.ssh/id_rsa type 0
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: identity file /root/.ssh/id_ecdsa type -1
debug1: identity file /root/.ssh/id_ecdsa-cert type -1
debug1: identity file /root/.ssh/id_ecdsa_sk type -1
debug1: identity file /root/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /root/.ssh/id_ed25519 type -1
debug1: identity file /root/.ssh/id_ed25519-cert type -1
debug1: identity file /root/.ssh/id_ed25519_sk type -1
debug1: identity file /root/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /root/.ssh/id_xmss type -1
debug1: identity file /root/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.5
debug1: Remote protocol version 2.0, remote software version Comware-7.1.064
debug1: compat_banner: no match: Comware-7.1.064
debug1: Authenticating to 172.16.0.1:22 as 'username'
debug1: load_hostkeys: fopen /root/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: diffie-hellman-group-exchange-sha1
debug1: kex: host key algorithm: ssh-rsa
debug1: kex: server->client cipher: 3des-cbc MAC: hmac-sha1 compression: none
debug1: kex: client->server cipher: 3des-cbc MAC: hmac-sha1 compression: none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(2048<7680<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_GROUP received
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: SSH2_MSG_KEX_DH_GEX_REPLY received
debug1: Server host key: ssh-rsa SHA256:94V6il+RjoLL+tfgN1tRtIS55hgwFOV9tnqTUNNZQh4
debug1: load_hostkeys: fopen /root/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug1: Host '172.16.0.1' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:6
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: /root/.ssh/id_rsa RSA SHA256:u9nA509C/UOwsz2vwC0lKE52yaZPpOLMXXMmTGpf4RQ
debug1: Will attempt key: /root/.ssh/id_dsa
debug1: Will attempt key: /root/.ssh/id_ecdsa
debug1: Will attempt key: /root/.ssh/id_ecdsa_sk
debug1: Will attempt key: /root/.ssh/id_ed25519
debug1: Will attempt key: /root/.ssh/id_ed25519_sk
debug1: Will attempt key: /root/.ssh/id_xmss
debug1: SSH2_MSG_SERVICE_ACCEPT received
- Description:HuLianWangYeWu *
- Any Unauthorized Login is Illegal !!! *
debug1: Authentications that can continue: password
debug1: Next authentication method: password
username@172.16.0.1's password:
debug1: Authentication succeeded (password).
Authenticated to 172.16.0.1 ([172.16.0.1]:22).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: pledge: filesystem full
debug1: Sending command: dir
exec request failed on channel 0
如果是分开执行就可以， 登录时不拼接命令，先登录成功，然后输入命令 dir 这样就可以完美执行。
网络上搜索，都是说什么进程数太小。这个不能解释为什么分开执行就可以。再一个，我的目标机器是h3c防火墙，没有那些配置可以修改。
我目前的猜测是h3c防火墙设置了一些规则，防止ssh 跟命令拼在一起。
