SSH克隆GitHub仓库失败，端口22超时如何解决？

已生成SSH密钥对并添加到Bitbucket和GitHub账号，能正常克隆组织的Bitbucket仓库，但无法通过SSH克隆组织的GitHub仓库。

克隆GitHub仓库失败的命令输出 #

git clone git@github.com:xxx/abc.git
Cloning into 'abc'...
ssh: connect to host github.com port 22: Connection timed out
fatal: Could not read from remote repository.

测试SSH连接github.com（端口22超时） #

ssh -vT git@github.com
OpenSSH_8.2p1 Ubuntu-4ubuntu0.5, OpenSSL 1.1.1f  31 Mar 2020
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: Connecting to github.com [20.207.73.82] port 22.
debug1: connect to address 20.207.73.82 port 22: Connection timed out
ssh: connect to host github.com port 22: Connection timed out

测试SSH连接ssh.github.com（端口443成功） #

ssh -vT -p 443 git@ssh.github.com
OpenSSH_8.2p1 Ubuntu-4ubuntu0.5, OpenSSL 1.1.1f  31 Mar 2020
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: Connecting to ssh.github.com [20.207.73.83] port 443.
debug1: Connection established.
debug1: identity file /home/myuser/.ssh/id_rsa type -1
debug1: identity file /home/myuser/.ssh/id_rsa-cert type -1
debug1: identity file /home/myuser/.ssh/id_dsa type -1
debug1: identity file /home/myuser/.ssh/id_dsa-cert type -1
debug1: identity file /home/myuser/.ssh/id_ecdsa type -1
debug1: identity file /home/myuser/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/myuser/.ssh/id_ecdsa_sk type -1
debug1: identity file /home/myuser/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /home/myuser/.ssh/id_ed25519 type 3
debug1: identity file /home/myuser/.ssh/id_ed25519-cert type -1
debug1: identity file /home/myuser/.ssh/id_ed25519_sk type -1
debug1: identity file /home/myuser/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /home/myuser/.ssh/id_xmss type -1
debug1: identity file /home/myuser/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.2p1 Ubuntu-4ubuntu0.5
debug1: Remote protocol version 2.0, remote software version babeld-6046b64f
debug1: no match: babeld-6046b64f
debug1: Authenticating to ssh.github.com:443 as 'git'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:p2QAMXNIC1TJYWeIOttrVc98/R1BUFWu3/LiyKgUfQM
debug1: checking without port identifier
The authenticity of host '[ssh.github.com]:443 ([20.207.73.83]:443)' can't be established.
ECDSA key fingerprint is SHA256:p2QAMXNIC1TJYWeIOttrVc98/R1BUFWu3/LiyKgUfQM.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '[ssh.github.com]:443,[20.207.73.83]:443' (ECDSA) to the list of known hosts.
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: /home/myuser/.ssh/id_ed25519 ED25519 SHA256:jQIcEmfKxygZTBMM2W22ia6pPFigVGBLUIqcFGSlxy4 agent
debug1: Will attempt key: /home/myuser/.ssh/id_rsa 
debug1: Will attempt key: /home/myuser/.ssh/id_dsa 
debug1: Will attempt key: /home/myuser/.ssh/id_ecdsa 
debug1: Will attempt key: /home/myuser/.ssh/id_ecdsa_sk 
debug1: Will attempt key: /home/myuser/.ssh/id_ed25519_sk 
debug1: Will attempt key: /home/myuser/.ssh/id_xmss 
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp256-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,sk-ecdsa-sha2-nistp256@openssh.com,ssh-ed25519,ecdsa-sha2-nistp521,ecdsa-sha2-nistp384,ecdsa-sha2-nistp256,rsa-sha2-512,rsa-sha2-256,ssh-rsa>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /home/myuser/.ssh/id_ed25519 ED25519 SHA256:jQIcEmfKxygZTB112W22ia6pPFigVGBLUIqcFGSlxy4 agent
debug1: Server accepts key: /home/myuser/.ssh/id_ed25519 ED25519 SHA256:jQIcEmfKxygZTB112W22ia6pPFigVGBLUIqcFGSlxy4 agent
debug1: Authentication succeeded (publickey).
Authenticated to ssh.github.com ([20.207.73.83]:443).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: pledge: network
debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
debug1: Sending environment.
debug1: Sending env LANG = en_IN
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
Hi my-github-username! You've successfully authenticated, but GitHub does not provide shell access.
debug1: channel 0: free: client-session, nchannels 1
Transferred: sent 2156, received 2552 bytes, in 0.4 seconds
Bytes per second: sent 5121.8, received 6062.6
debug1: Exit status 1

公司VPN大概率封禁了SSH默认的22端口，但允许443端口通行。通过配置SSH客户端规则，让所有github.com的请求自动走ssh.github.com的443端口即可解决：

1. 打开（或创建）~/.ssh/config文件
2. 添加以下内容：

Host github.com
  Hostname ssh.github.com
  Port 443
  User git

3. 保存文件后，重新测试SSH连接：ssh -vT git@github.com，此时应该能成功完成认证
4. 再执行git clone git@github.com:xxx/abc.git即可正常克隆仓库

如果之前已克隆仓库但无法进行push/pull操作，可修改仓库的远程地址：

git remote set-url origin git@github.com:xxx/abc.git

内容的提问来源于stack exchange，提问作者Sachin Sheelavant