Telnet to SSH Migration

Secure Your Remote Access – Replace Telnet with SSH

Expert guidance and hands-on migration from insecure Telnet to modern, encrypted SSH — eliminating clear-text credentials while maintaining functionality for legacy systems and scripts.

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Our Telnet to SSH Migration Services

Telnet remains in use in many legacy environments despite sending passwords and data in clear text. Zwiegnet specializes in secure, low-risk migrations from Telnet to SSH across Linux, Solaris, FreeBSD, and other Unix platforms — protecting credentials and sessions without disrupting operations.

We handle the full migration process:

Assessment & Inventory – Identification of Telnet servers, clients, embedded devices, scripts, and automated processes relying on Telnet.
SSH Server Deployment – Installation and configuration of OpenSSH on Linux/Solaris/FreeBSD with compatible settings (Protocol 2, legacy ciphers if needed temporarily).
Authentication Migration – Transition from password to key-based authentication, SSH certificates, or integration with LDAP/Kerberos for centralized credentials.
Client & Script Updates – Replacement of telnet commands with ssh/scp/sftp in scripts, expect automation, cron jobs, and monitoring tools.
Legacy Compatibility – Temporary support for older clients (e.g., PermitOpen, ForceCommand, restricted shells) and tunneling for non-SSH-aware applications.
Security Hardening – Disable Telnet/insecure services, enforce strong ciphers, Fail2Ban integration, two-factor authentication, and audit logging.
Port & Service Mapping – Running SSH on port 23 temporarily for seamless client transition, then migrating to standard port 22.
High Availability & Load Balancing – Multi-node SSH access with shared keys, load-balanced jump hosts, or SSH over HAProxy.
Testing & Parallel Operation – Side-by-side Telnet/SSH operation during transition, user acceptance testing, and automated connectivity checks.
Cutover & Decommissioning – Phased client migration, final Telnet shutdown, and verification of all connections using SSH.
Post-Migration Support – Ongoing SSH management, key rotation, monitoring, and user training.

Benefits include encrypted sessions, stronger authentication, reduced attack surface, and compliance with modern security standards — all while preserving legacy workflows.

Located between Madison and Milwaukee, Wisconsin since 2009 — direct, personal service with proven Telnet-to-SSH migration experience in sensitive and legacy environments.

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