Troubleshooting SSH stuck on “Connecting to server” – WP Reset

Secure Shell (SSH) is a crucial component for remotely managing and administering servers. It can be frustrating if you’re stuck at the “Connecting to server” message in your SSH client, especially if you’re dealing with production environments or time-sensitive configurations. This issue may seem vague, but there are several possible causes, ranging from network misconfigurations to issues with the SSH daemon on the target server. Knowing how to effectively troubleshoot SSH connectivity issues will save you time and unnecessary stress.

TL; DR

If your SSH session hangs on “Connecting to server”, first check the availability and network connectivity of the target host. Verify that the SSH service is running on the destination and listening on the correct port. Then check your local firewall, DNS resolution or VPN settings. Use verbose SSH logging (-vvv) for more insight during the connection attempt.

1. Confirm basic network connectivity

Before you dive deep into the configurations and logs, start with the simplest checks:

• Ping the server: Usage ping to verify that the host is reachable.
• Traceroute or MTR: This can help determine if there is a connectivity block on a network jump between you and the SSH server.
• Telnet or Netcat: Try accessing port 22 (or the custom SSH port) to confirm that it is accessible: telnet your.server.ip 22 or nc -zv your.server.ip 22

If the server does not respond to ping or refuses the SSH port, the host is offline, the network is blocking traffic, or SSH is not working properly on the server.

2. Use extended mode to gain insight

SSH offers different levels of verbosity that can help determine where in the connection process the delay occurs. Use the -v, -vvor -vvv options to get more detailed output:

ssh -vvv user@your.server.ip

Common locations where extended mode helps include:

• Check DNS resolution
• Determine whether the connection attempt times out at a certain step
• Identification of key exchange or authentication errors

3. Firewall and security group settings

Often firewalls or cloud security settings are the culprits. You need to check the following on both your client side and server side:

• Client-side firewall: Make sure outbound connections are allowed on port 22 (or your custom SSH port).
• Server side firewall: Tools such as iptables or ufw can drop incoming SSH traffic.
• Cloud security groups: In AWS, GCP, or Azure environments, verify that the security group allows your IP address and the correct port.

If your connection hangs at ‘Connecting’, this may indicate that packets are being silently dropped rather than actively rejected.

4. Check the SSH daemon on the server

If you have alternate access to the server (for example via console, serial access or another remote session), log in immediately and authenticate the SSH service:

sudo systemctl status sshd

sudo netstat -tulpn | grep ssh

Things to watch out for:

• Is the service up and running?
• Is it listening on the expected IP address and port?
• Have there been any recent changes to the SSH configuration file (usually /etc/ssh/sshd_config) that can cause disruptions?

If SSH was recently reconfigured or restarted incorrectly, the process may be stuck or unresponsive to incoming connections.

5. DNS resolution issues

If you are connecting to a hostname instead of an IP address, make sure DNS resolves correctly:

nslookup your.server.domain

dig your.server.domain

Issues with DNS settings can slow down or interrupt your SSH connection if the hostname cannot be resolved. Also check your /etc/resolv.conf or DNS settings in your router or VPN.

6. TCP Wrappers and Host-Based Restrictions

On some Linux distributions, TCP wrappers are controlled via /etc/hosts.allow And /etc/hosts.deny—can restrict SSH access:

• Make sure /etc/hosts.deny does not contain a line like sshd: ALL
• Explicitly allow your IP /etc/hosts.allow of sshd: your.ip.address

Although TCP wrappers are largely outdated, older systems can still use them without obvious indications in logs.

7. VPN or proxy interference

VPNs and certain proxy settings can interfere with SSH traffic:

• Make sure your VPN is active and forwarding your traffic correctly.
• If you are using a split VPN tunnel, check that the traffic to the SSH server is included in the tunnel.
• Try temporarily disabling the VPN and reconnecting using direct Internet access.

Similarly, corporate proxies or throttling gateways can drop or manipulate SSH packets, resulting in session crashes.

8. SSH key issues and authentication delays

While authentication failures typically result in a clear “Permission Denied” message, long delays in key processing or authorized key lookups can sometimes mimic a hung connection.

• Too many keys in your ~/.ssh directory may delay authentication. Usage IdentitiesOnly yes in ~/.ssh/config attempts to reduce.
• Configure a specified key: ssh -i ~/.ssh/my_key user@host

9. Server Load and Resource Limitations

A heavily loaded server can slow down or even block new SSH connections:

• Check for high CPU, RAM, or process limits on the server
• If access is not possible via SSH, use a cloud console to inspect the system status

Low memory situations can cause this sshd behaving erratically or simply timing out new connection attempts.

10. Temporarily banned by Fail2Ban or similar tools

Security tools such as Fail2Ban or DenyHosts can block IP addresses where authentication has failed repeatedly. This can cause the silent connection to hang:

• Check for IP bans /var/log/fail2ban.log or related logs
• Whitelist your IP where possible or access the server from another network

Conclusion

SSH connection issues (especially stuck on “Connecting to server”) can be due to several factors, ranging from local firewall settings to performance issues with remote servers. A disciplined approach to troubleshooting that starts with simple connectivity tests and progresses to in-depth logging and configuration checks is essential. By using tools like extended SSH execution, viewing system logs, validating DNS, and ensuring your server is responsive, you can efficiently isolate the root cause.

Please note: always test changes incrementally and make a backup of any configurations you change. In high availability environments, having an out-of-band management method, such as IPMI, serial console, or primary server access, is critical when SSH is unresponsive.