问题
I am in need of python sftp client to download files from a sftp server. I started to use Paramiko. Small files in KB works well but however when I try to download 600 MB of file, it hangs indefinitely after downloading 20 MB of file. Unable to figure out what the issue is. Increasing the window size did not solve either. Any help would be much appreciated!
host = config.getsafe(section, "host")
username = config.getsafe(section, "username")
port = config.getsafe(section, "port")
remote_dir = config.getsafe(section, "remote_dir")
download_dir = config.getsafe(section, "download_dir")
archive_dir = config.getsafe(section, "archive_dir") if config.has_option(section, "archive_dir") else \
None
password = config.getsafe(section, "password") if config.has_option(section, "password") else None
file_pattern = config.getsafe(section, "file_pattern") if config.has_option(section, "file_pattern") \
else "*"
passphrase = config.getsafe(section, "passphrase") if config.has_option(section, "passphrase") else None
gnupg_home = config.getsafe(section, "gnupg_home") if config.has_option(section, "gnupg_home") else None
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(hostname=host, port=int(port), username=username, password=password)
sftp = ssh.open_sftp()
sftp.sshclient = ssh
sftp.get("/SFTP/PL_DEV/test.dat", "C:/import/download/test.dat")
回答1:
I did two things to solve a similar problem:
increase window size – you say you tried that too; for me, this helped to get from a few ten MBs to half a GB but no further
effectively disable rekeying – this might have security implications, but helped me to get files over a GB from a weird windows sftp server
with paramiko.Transport((_SFTP['host'], 22)) as transport: # SFTP FIXES transport.default_window_size=paramiko.common.MAX_WINDOW_SIZE transport.packetizer.REKEY_BYTES = pow(2, 40) # 1TB max, this is a security degradation! transport.packetizer.REKEY_PACKETS = pow(2, 40) # 1TB max, this is a security degradation! # / SFTP FIXES transport.connect(username=_SFTP['user'], password=_SFTP['password']) with paramiko.SFTPClient.from_transport(transport) as sftp: listdir = sftp.listdir() # ... sftp.get(remotepath=filename, localpath=localpath)
回答2:
Increasing default_max_packet_size and default_window_size as follows worked for me:
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.load_system_host_keys()
client.connect(hostname, username=username, password=password, port=port)
tr = client.get_transport()
tr.default_max_packet_size = 100000000
tr.default_window_size = 100000000
sftp = client.open_sftp()
sftp.get(remote_file, local_filepath)
client.close()
回答3:
Using the latest paramiko 2.4.2, I have a similar issue. In my case, our vendor switched their SFTP provider from Globalscape (SSH-2.0-1.82_sshlib Globalscape) to Cerberus (SSH-2.0-CerberusFTPServer_10.0) a few days ago. Ever since then, paramiko has been unable to download a ~450MB file.
Here is the symptom:
The downloading speed is extremely slow. After downloading 20~30MB, it always errors out with:
Server connection dropped msg.
Here is the log (Globalscape) - successful download:
"paramiko.transport", "DEBUG", "starting thread (client mode): 0x160096d8"
"paramiko.transport", "DEBUG", "Local version/idstring: SSH-2.0-paramiko_2.4.1"
"paramiko.transport", "DEBUG", "Remote version/idstring: SSH-2.0-1.82_sshlib Globalscape"
"paramiko.transport", "INFO", "Connected (version 2.0, client 1.82_sshlib)"
"paramiko.transport", "DEBUG", "kex algos:['diffie-hellman-group14-sha1', 'diffie-hellman-group-exchange-sha1', 'diffie-hellman-group1-sha1'] server key:['ssh-rsa'] client encrypt:['twofish256-cbc', 'twofish-cbc', 'twofish128-cbc', 'blowfish-cbc', '3des-cbc', 'arcfour', 'cast128-cbc', 'aes256-cbc', 'aes128-cbc', 'aes256-ctr', 'aes128-ctr'] server encrypt:['twofish256-cbc', 'twofish-cbc', 'twofish128-cbc', 'blowfish-cbc', '3des-cbc', 'arcfour', 'cast128-cbc', 'aes256-cbc', 'aes128-cbc', 'aes256-ctr', 'aes128-ctr'] client mac:['hmac-sha1', 'hmac-md5', 'hmac-sha1-96', 'hmac-md5-96'] server mac:['hmac-sha1', 'hmac-md5', 'hmac-sha1-96', 'hmac-md5-96'] client compress:['zlib', 'none'] server compress:['zlib', 'none'] client lang:[''] server lang:[''] kex follows?False"
"paramiko.transport", "DEBUG", "HostKey agreed: ssh-rsa"
"paramiko.transport", "DEBUG", "Cipher agreed: aes128-ctr"
"paramiko.transport", "DEBUG", "MAC agreed: hmac-sha1"
"paramiko.transport", "DEBUG", "Compression agreed: none"
"paramiko.transport", "DEBUG", "Got server p (2048 bits)"
"paramiko.transport", "DEBUG", "kex engine KexGex specified hash_algo <built-in function openssl_sha1>"
"paramiko.transport", "DEBUG", "Switch to new keys ..."
"paramiko.transport", "DEBUG", "Attempting public-key auth..."
"paramiko.transport", "DEBUG", "userauth is OK"
"paramiko.transport", "INFO", "Auth banner: b'Welcome to the our Secure FTP Server'"
"paramiko.transport", "INFO", "Authentication (publickey) successful!"
"paramiko.transport", "DEBUG", "[chan 0] Max packet in: 32768 bytes"
"paramiko.transport", "DEBUG", "[chan 0] Max packet out: 35840 bytes"
"paramiko.transport", "DEBUG", "Secsh channel 0 opened."
"paramiko.transport", "DEBUG", "[chan 0] Sesch channel 0 request ok"
"paramiko.transport.sftp", "INFO", "[chan 0] Opened sftp connection (server version 3)"
"paramiko.transport.sftp", "DEBUG", "[chan 0] stat(b'data.csv')"
"paramiko.transport.sftp", "DEBUG", "[chan 0] open(b'data.csv', 'rb')"
"paramiko.transport.sftp", "DEBUG", "[chan 0] open(b'data.csv', 'rb') -> 31"
"paramiko.transport.sftp", "DEBUG", "[chan 0] close(31)"
"paramiko.transport.sftp", "INFO", "[chan 0] sftp session closed."
"paramiko.transport", "DEBUG", "[chan 0] EOF sent (0)"
"paramiko.transport", "DEBUG", "EOF in transport thread"
Here is the log (Cerberus) - failed download:
"paramiko.transport", "DEBUG", "starting thread (client mode): 0x119706d8"
"paramiko.transport", "DEBUG", "Local version/idstring: SSH-2.0-paramiko_2.4.1"
"paramiko.transport", "DEBUG", "Remote version/idstring: SSH-2.0-CerberusFTPServer_10.0"
"paramiko.transport", "INFO", "Connected (version 2.0, client CerberusFTPServer_10.0)"
"paramiko.transport", "DEBUG", "kex algos:['ecdh-sha2-nistp256', 'ecdh-sha2-nistp384', 'ecdh-sha2-nistp521', 'diffie-hellman-group-exchange-sha256', 'diffie-hellman-group-exchange-sha1', 'diffie-hellman-group14-sha1', 'diffie-hellman-group1-sha1'] server key:['ssh-rsa'] client encrypt:['aes128-ctr', 'aes128-cbc', 'aes192-ctr', 'aes192-cbc', 'aes256-ctr', 'aes256-cbc', '3des-cbc'] server encrypt:['aes128-ctr', 'aes128-cbc', 'aes192-ctr', 'aes192-cbc', 'aes256-ctr', 'aes256-cbc', '3des-cbc'] client mac:['hmac-sha1', 'hmac-sha1-96', 'hmac-sha2-256', 'hmac-sha2-256-96', 'hmac-sha2-512', 'hmac-sha2-512-96', 'hmac-ripemd160', 'hmac-ripemd160@openssh.com', 'hmac-md5'] server mac:['hmac-sha1', 'hmac-sha1-96', 'hmac-sha2-256', 'hmac-sha2-256-96', 'hmac-sha2-512', 'hmac-sha2-512-96', 'hmac-ripemd160', 'hmac-ripemd160@openssh.com', 'hmac-md5'] client compress:['none'] server compress:['none'] client lang:['en-US'] server lang:['en-US'] kex follows?False"
"paramiko.transport", "DEBUG", "Kex agreed: ecdh-sha2-nistp256"
"paramiko.transport", "DEBUG", "HostKey agreed: ssh-rsa"
"paramiko.transport", "DEBUG", "Cipher agreed: aes128-ctr"
"paramiko.transport", "DEBUG", "MAC agreed: hmac-sha2-256"
"paramiko.transport", "DEBUG", "Compression agreed: none"
"paramiko.transport", "DEBUG", "kex engine KexNistp256 specified hash_algo <built-in function openssl_sha256>"
"paramiko.transport", "DEBUG", "Switch to new keys ..."
"paramiko.transport", "DEBUG", "Attempting public-key auth..."
"paramiko.transport", "DEBUG", "userauth is OK"
"paramiko.transport", "INFO", "Authentication (publickey) successful!"
"paramiko.transport", "DEBUG", "[chan 0] Max packet in: 32768 bytes"
"paramiko.transport", "DEBUG", "[chan 0] Max packet out: 32768 bytes"
"paramiko.transport", "DEBUG", "Secsh channel 0 opened."
"paramiko.transport", "DEBUG", "[chan 0] Sesch channel 0 request ok"
"paramiko.transport.sftp", "INFO", "[chan 0] Opened sftp connection (server version 3)"
"paramiko.transport.sftp", "DEBUG", "[chan 0] stat(b'data.csv')"
"paramiko.transport.sftp", "DEBUG", "[chan 0] open(b'data.csv', 'rb')"
"paramiko.transport.sftp", "DEBUG", "[chan 0] open(b'data.csv', 'rb') -> 7b45394343333830462d383832352d343436342d393831302d4444373838314237303433367d"
"paramiko.transport", "DEBUG", "EOF in transport thread"
Adding
transport.default_window_size = paramiko.common.MAX_WINDOW_SIZE
works for me (at least for now). Not sure what would happen if the file size increases from ~450MB to >>0.5GB.
来源：https://stackoverflow.com/questions/45891553/paramiko-hangs-on-get-after-ownloading-20-mb-of-file