Cannot scp file to an EC2 instance that I can ssh to

Question

I have two EC2 instances that were created from the same AMI, which was created from the Amazon Linux AMI. These are running mysql in a master-slave configuration. The security group ("db") is configured to allow port 22 from instances running under security group "web".

So, I ssh into one of the web instances, and then ssh or scp to the database instances. This has been working fine for a while.

Today, however, I can no longer scp to one of the instances (the master). I can ssh into it just fine, and both scp and ssh work fine to the slave instance.

Running scp with -vv produces almost idential output, up to the debug2: line below, which is the last output when connecting to the master.

debug2: exec request accepted on channel 0
Sending file modes: C0775 77 <filename>

Any idea what is going on? I've tried re-starting the instance, and that didn't make any difference.

Update:

/var/log/secure:
  Jan 10 19:02:59 <host> sshd[1987]: Accepted publickey for <user> from xx.xxx.xxx.xxx port 33285 ssh2
  Jan 10 19:02:59 <host> sshd[1987]: pam_unix(sshd:session): session opened for user <user> by (uid=0)

There were about 20 lines or so added to /var/log/audit/audit.log, all ending in res=success

Answer 1

I fixed this issue by doing the following:

$ sudo vi /etc/ssh/sshd_config

Changed this:

# override default of no subsystems
Subsystem      sftp    /usr/libexec/openssh/sftp-server

To this:

# override default of no subsystems
Subsystem      sftp    internal-sftp

Then restarted the sshd service:

$ sudo service sshd restart

Answer 2

I find it easier to just run a python SimpleHTTPServer and run wget on other side to download file.

• Add HTTP procotcol to be added in security config for all sources

• run the following command in the directory in which file exists

  $ sudo python -m SimpleHTTPServer 80

• on the receiving side, run the following command to download file

  $ wget http://ec2ip.aws.amaxon.com/file.txt