SCP Stalled : Server to Oracle VM

Question

I have a oracle VM as a test environment, when I try to scp some files from my production server it always get stalled. Sometimes with very small file <5kb scp runs successfully. Please help.

PS: Both machines run on Centos 6.4

Logs:

[root@mygw tmp]# scp -v -P#port# myuser@#myip#://#path#/#file#.sql.gz /tmp
Executing: program /usr/bin/ssh host #myip#, user myuser, command scp -v -f //#path#/#file#.sql.gz
OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to #myip# [#myip#] port #port#.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host '[#myip#]:#port#' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/identity
debug1: Trying private key: /root/.ssh/id_rsa
debug1: Trying private key: /root/.ssh/id_dsa
debug1: Next authentication method: password
myuser@#myip#'s password: 
debug1: Authentication succeeded (password).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
debug1: Sending command: scp -v -f //#path#/#file#.sql.gz
Sink: C0644 15557576 #file#.sql.gz
#file#.sql.gz                                                                                                                                           0%    0     0.0KB/s   --:-- ETASending file modes: C0644 15557576 #file#.sql.gz
#file#.sql.gz                                                                                                                                           0%    0     0.0KB/s - stalled -

Please provide some logs, for example output of scp with -v option. — b13n1u, Jul 07 '14 at 11:44
If you have any other servers in your network, is scp fast from some other server to Oracle? Or is scp fast between $some_other_server_1 <--> $some_other_server_2? Perhaps some firewall is throttling the connection. — Janne Pikkarainen, Jul 07 '14 at 12:18
By copying files from one server to another back and forth. And if you meant the firewall, then ask from the network administrators you might have. :) — Janne Pikkarainen, Jul 07 '14 at 14:02
I did the test and it worked (Server to server), I'm supposed to be "the network administrator" , I did the test in my VM with firewall disabled both sides but still getting stalled. — elarichi.y, Jul 08 '14 at 14:15

Roy · Answer 1 · 2017-10-16T15:58:51.053

This sounds like a traditional MTU problem, which makes sense if you have VLANs configured in the Oracle VM environment and some part of your network equipment does not support 802.11q VLAN tags.

Typically it would caused by an older network card or perhaps a small switch for home and small office. Often the case if you happen to build a lab on retired hardware or desktop computers.

You can work around the problem by setting MTU to 1498 on both end-points. If that solves it, you know what you are dealing with.

SCP Stalled : Server to Oracle VM

1 Answers1