SSH and Networking
How to Audit SSH Logins and Failed Attempts the Safe Way
Audit SSH logins on Linux: read auth logs and the journal, count failed attempts, list successful logins by key, spot invalid users and raise the log level.
6 min read
Topic
SSH and Networking
SSH keys and tunnels, curl, DNS lookups and port checks, for when a connection will not come up.
SSH and Networking
How to Use Hardware Keys With SSH Without Surprises
Use a FIDO2 hardware key for SSH: generate an ed25519-sk key, choose resident or not, require touch and PIN, use it on new machines and keep a backup.
6 min read
Go
How to Write an SSH Client Script in Go With Examples
Write an SSH client in Go with golang.org/x/crypto/ssh: key or agent authentication, verified host keys through known_hosts, timeouts and running a command.
6 min read
Go
How to Write a Simple TCP Port Scanner in Go in Real Scripts
Write a simple concurrent TCP port scanner in Go with net.DialTimeout, a bounded worker pool, sorted results and notes on filtered versus closed ports.
6 min read
Command Line
How to Use scp and sftp to Transfer Files With Real Output
Use scp and sftp to copy files over SSH, with ports, keys and recursive copies, learn how scp changed in OpenSSH 9, and when to use rsync instead.
6 min read
Tooling
How to Use VS Code Remote SSH and Dev Containers Properly
Use VS Code Remote SSH and Dev Containers: connect with your ssh config, devcontainer.json, features, ports and the problems to expect.
6 min read
Tooling
How to Set Up a Remote Dev Machine and Edit Over SSH
Set up a remote dev machine and edit over SSH: host config, connection reuse, tmux, port forwarding, editors over SSH and file sync.
6 min read
SSH and Networking
SSH No Matching Host Key Type Found With Every Cause
Fix SSH no matching host key type found: why SHA-1 ssh-rsa was disabled, reading the server offer, HostKeyAlgorithms overrides, and re-keying.
6 min read
SSH and Networking
SSH No Matching Key Exchange Method Found Causes and Fixes
Fix SSH no matching key exchange method found: read the server offer, old server versus new client, safe KexAlgorithms overrides and upgrades.
6 min read
SSH and Networking
SSH Unprotected Private Key File Warning and How to Fix It
Fix the SSH unprotected private key file warning: set mode 600, fix ownership, handle WSL and Windows mounts, and see why open keys are refused.
6 min read
SSH and Networking
SSH Host Key Verification Failed Explained With Every Cause
Understand SSH Host key verification failed: every cause, from a changed key or unwritable known_hosts to a non-interactive session, with the fix for each.
6 min read
Git
How to Change a Git Remote URL From HTTPS to SSH Easily
Change a Git remote URL from HTTPS to SSH with git remote set-url: find the SSH address, test the connection, and fix credential and key problems.
6 min read
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