Aspera ascp Command Fails with "Failed to open TCP connection for SSH" Error

Question

[Akansh]

Hello Biostars community,

I'm encountering an issue while attempting to download a file using the Aspera ascp command. Here’s the command I’m using:

"ascp -QT -l 100M -P 33001 [e-mail]:/sra/sra-instant/reads/ByRun/sra/SRR/SRR123/SRR123456/SRR123456.sra . "

However, I receive the following error: --> ascp: Failed to open TCP connection for SSH, exiting.

Session Stop (Error: Failed to open TCP connection for SSH)

Has anyone experienced a similar issue, or does anyone have suggestions for troubleshooting this? Any help would be greatly appreciated.

[Michael]

The most likely explanation are firewall issues or rarely problems with the internet connection. (given this is a valid Download URL!) See https://www.ibm.com/support/pages/ascp-connectivity-testing and https://www.ibm.com/docs/en/ahts/4.3?topic=upgrades-configuring-firewall#configuring-the-firewall__section_jlp_z3v_cy__title__1

If you can, talk to your friendly IT operator or try a different network.

Answer 1

[ATpoint]

Two things: First, this accession is under access control, so you need to apply for access via dbGaP and then use prefetch to download that file. Second, in general, I am quite sure NCBI moved the SRA files away from their ftp servers to some sort of cloud so I think even without access restrict this command would fail. Note sure though.

atpoint@foo:~$ prefetch SRR123456

2024-08-08T11:48:51 prefetch.2.11.3 err: libs/vfs/names4-response.c:1937:ContainerProcessStatus: query unauthorized while resolving query within virtual file system module - failed to resolve accession 'SRR123456' - Access denied - please request permission to access phs000298 / DS-ASD in dbGaP. ( 403 )

Mind the Access denied - please request permission to access phs000298 / DS-ASD in dbGaP.

[Michael]

You're right: https://github.com/ncbi/sra-tools/wiki/Avoid-using-ascp-directly-for-downloads

Answer 2

[Michael]

The answer is: don't! Use SRA tools and prefetch to download from SRA. The reasons are given here: https://github.com/ncbi/sra-tools/wiki/Avoid-using-ascp-directly-for-downloads https://github.com/ncbi/sra-tools/issues/304