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> Greg MacSweeney, a spokesperson for The Clearing House, said the problem was caused by a “manual error” and is not linked to a cybersecurity issue. Surprisin

> Greg MacSweeney, a spokesperson for The Clearing House, said the problem was caused by a “manual error” and is not linked to a cybersecurity issue. Surprisingly, this explanation doesn't make me feel better about the problem. Is there some guy manually running batch jobs to keep everything going?

traviswingo 3y ago
AFAIK ACH is incredibly archaic. There are real reasons why money can’t transfer outside of business hours. It’s honestly bizarre to me.
- mistrial9 3y ago
  ultimately it is the negotiated contract between distrusting parties, with all of its warts, right? CS people might really get a shock out of how daily systems "work"
ganeshkrishnan 3y ago
All the clearing is (at least used to 10 years ago) done by manual SFTP transfers of transactions from one place to another. This is how inter-bank communications are done. Another process verifies the transactions later and checks if they match up. But yes, the process is archaic & simple with file drops, reads and processing. I worked on the EUR-GBP bank clearance software
- amluto 3y ago
  SFTP is a bizarre protocol for this, given that there isn’t any way for a process on the server to know that the client is done sending data. Yes, there are ways to bolt such a thing on top of SFTP. As far as I know, no one actually does this.
  - GauntletWizard 3y ago
    The protocol doesn't need to be that complex. A footer works. As does a move from the "incoming" to "to process" folder. But yes, most banking protocols have nothing of the sort.
- rootsudo 3y ago
  Can confirm that SFTP still is being used to clear ACH and SWIFT Wires.
  - JumpCrisscross 3y ago
    > SFTP still is being used to clear ACH and SWIFT Wires Nitpick, ACH clears (i.e. moves money). SWIFT is just a messaging protocol—you have to clear on your own. (Usually through a correspondent bank.)
  - CSSer 3y ago
    Are they batched into some binary/serialized format that ships a collection of transactions that is then processed on the other system one at a time or literally shipped via individual network transactions and then executed individually? If it’s the latter that just seems wild.
    - cosmie 3y ago
      They're specifically formatted ASCII text files[1][2]. A single file can have multiple batches. A single batch can have multiple transactions. For example, a company may upload an ACH file to their bank for payroll that contains a single batch in it and in that single batch they have entries for each employee's payroll deposit. Or maybe it has two batches – one for payroll deposits and a second one for reimbursements (or bonuses) that get deposited separately. Maybe it even has batches for things like 401k transfers to custodian accounts. Their bank may receive that batch file, validate that and combine those batches with all the other ones it has and send those as a combined file to the clearing house.[3] That said, nothing stops you from transfer if a file with a single batch containing a single transaction. Such as when you need to initiate an immediate transfer instead of collating it with all the other transactions at the end of the day. At the end of the day, the ACH network is just a bunch of text files being pushed to sftp servers and servers periodically polling for new text files in those sftp directories to pick up and process. [1] https://achdevguide.nacha.org/ach-file-overview https://achdevguide.nacha.org/ach-file-overview [2] https://github.com/moov-io/ach/blob/master/docs/file-structure.md https://github.com/moov-io/ach/blob/master/docs/file-structu... [3] My understanding of this aspect is vague at best, so may be misconstruing how they're aggregated or passed through to the clearing house.

traviswingo 3y ago

AFAIK ACH is incredibly archaic. There are real reasons why money can’t transfer outside of business hours. It’s honestly bizarre to me.

mistrial9 3y ago
ultimately it is the negotiated contract between distrusting parties, with all of its warts, right? CS people might really get a shock out of how daily systems "work"

ganeshkrishnan 3y ago

All the clearing is (at least used to 10 years ago) done by manual SFTP transfers of transactions from one place to another. This is how inter-bank communications are done. Another process verifies the transactions later and checks if they match up. But yes, the process is archaic & simple with file drops, reads and processing. I worked on the EUR-GBP bank clearance software

amluto 3y ago
SFTP is a bizarre protocol for this, given that there isn’t any way for a process on the server to know that the client is done sending data. Yes, there are ways to bolt such a thing on top of SFTP. As far as I know, no one actually does this.
- GauntletWizard 3y ago
  The protocol doesn't need to be that complex. A footer works. As does a move from the "incoming" to "to process" folder. But yes, most banking protocols have nothing of the sort.
rootsudo 3y ago
Can confirm that SFTP still is being used to clear ACH and SWIFT Wires.
- JumpCrisscross 3y ago
  > SFTP still is being used to clear ACH and SWIFT Wires Nitpick, ACH clears (i.e. moves money). SWIFT is just a messaging protocol—you have to clear on your own. (Usually through a correspondent bank.)
- CSSer 3y ago
  Are they batched into some binary/serialized format that ships a collection of transactions that is then processed on the other system one at a time or literally shipped via individual network transactions and then executed individually? If it’s the latter that just seems wild.
  - cosmie 3y ago
    They're specifically formatted ASCII text files[1][2]. A single file can have multiple batches. A single batch can have multiple transactions. For example, a company may upload an ACH file to their bank for payroll that contains a single batch in it and in that single batch they have entries for each employee's payroll deposit. Or maybe it has two batches – one for payroll deposits and a second one for reimbursements (or bonuses) that get deposited separately. Maybe it even has batches for things like 401k transfers to custodian accounts. Their bank may receive that batch file, validate that and combine those batches with all the other ones it has and send those as a combined file to the clearing house.[3] That said, nothing stops you from transfer if a file with a single batch containing a single transaction. Such as when you need to initiate an immediate transfer instead of collating it with all the other transactions at the end of the day. At the end of the day, the ACH network is just a bunch of text files being pushed to sftp servers and servers periodically polling for new text files in those sftp directories to pick up and process. [1] https://achdevguide.nacha.org/ach-file-overview https://achdevguide.nacha.org/ach-file-overview [2] https://github.com/moov-io/ach/blob/master/docs/file-structure.md https://github.com/moov-io/ach/blob/master/docs/file-structu... [3] My understanding of this aspect is vague at best, so may be misconstruing how they're aggregated or passed through to the clearing house.