ERC20 vulnerability? Executing transferFrom undesirably

Say I have contract A, and I require to send 100000 DAI to it. Ideally, I’d firstly call approve(<address of A>, 100000e18) in DAI’s contract itself. Secondly, I’d execute, for instance, the function collectDAI(100e18) from contract A. This function will internally call transferFrom(msg.sender, address(this), 100000e18) in DAI’s contract and update the contract’s state accordingly. Well,…

Discover more

Bitcoin Orphan blocks – short question about the “time lag” factor and proof-of-work “size”

“However, it is possible that two miners produce a block at a similar time. This situation occurs because the acceptance of the blocks into the blockchain by the nodes of the blockchain network does not happen instantaneously. This time lag in accepting a block may lead to another miner solving for the same exact block.…

Discover more

SSHFS: Cannot umount / re-mount remote directory after connection is interrupted

I often use sshfs to mount a remote directory to make it appear as local: sudo sshfs -o allow_other myname@server:/remote/path /mnt/remote/ Occasionally there could be interruption to the connection so /mnt/remote will appear as empty. If I try to re-run the above command, I’d get ‘/mnt/remote:’ Transport endpoint is not connected’ However I’m unable to…

Discover more

Performance differences between multiple vhosts vs single vhost on same server?

Is there a performance difference between 1000 concurrent connection with single vhost vs 100 concurrent connections with 10 vhost on same server? I created 2 diagrams of my project which one is better option for performance wise? More Info : Apache server , laravel (php) application with mysql database. Project Diagram 1 vs Project Diagram…

Discover more

Can’t send secure cookies using node and a ProxyPass/ProxyPassReverse (Httpd/Amazon linux)

I am still pretty new but I am using an Amazon linux image and httpd to encrypt and decrypt SSL requests. Then I Proxy those messages to and from a NodeJS app running on port 3001. To do this I have the following in my /etc/httpd/conf.d/ssl.conf <VirtualHost _default_:443> … ProxyPreserveHost On ProxyPass / http://*IP*:3001/ ProxyPassReverse…

Discover more

vsftpd.service don’t start with error ExecStart=/usr/sbin/vsftpd /etc/vsftpd.conf (code=exited, status=2)

I have a VM and I want to upload/download file so I’ve installed vsftpd, but if I start the service I get this error: ● vsftpd.service – vsftpd FTP server Loaded: loaded (/lib/systemd/system/vsftpd.service; enabled; vendor preset: enabled) Active: failed (Result: exit-code) since Thu 2019-11-14 20:57:51 CET; 2s ago Process: 1637 ExecStartPre=/bin/mkdir -p /var/run/vsftpd/empty (code=exited, status=0/SUCCESS)…

Discover more