How to fix kex_exchange_identification: Connection closed by remote host in Git

GitINTERMEDIATEMEDIUM

The server closed the connection during SSH authentication or data transfer. This typically happens due to network issues, SSH configuration problems, or server-side restrictions like rate limiting or IP blocking.

What this error means

This error occurs when a Git remote server abruptly terminates the SSH connection during the key exchange phase or while transferring data. The message "Connection closed by remote host" indicates the server actively closed the connection rather than a network timeout. Common variations include "fatal: The remote end hung up unexpectedly" during push/pull operations, or "ssh_exchange_identification: Connection closed by remote host" during the initial SSH handshake. The error typically appears when using SSH to communicate with remote Git repositories (GitHub, GitLab, Bitbucket, or self-hosted servers). It can occur during clone, fetch, push, or pull operations. The root cause usually falls into one of several categories: network connectivity issues, SSH authentication problems, server-side security restrictions (IP allowlists, rate limiting), or resource exhaustion on the remote server.

How to fix "kex_exchange_identification: Connection closed by remote host"

1Test SSH connection to verify the issue

First, confirm the connection problem is SSH-related and not specific to Git:

bash

# Test GitHub connection
ssh -T [email protected]

# Test GitLab connection
ssh -T [email protected]

# Test Bitbucket connection
ssh -T [email protected]

If this fails with the same error, the issue is with SSH connectivity, not Git specifically.

2Configure SSH keep-alive to prevent timeouts

Add keep-alive settings to your SSH config to maintain the connection:

bash

# Edit your SSH config file
nano ~/.ssh/config

# Add these lines
Host *
    ServerAliveInterval 60
    ServerAliveCountMax 30

This sends a keep-alive packet every 60 seconds for up to 30 rounds (30 minutes total), preventing idle connection timeouts.

For immediate testing without editing config:

bash

ssh -o ServerAliveInterval=60 -o ServerAliveCountMax=30 -T [email protected]

3Use SSH over port 443 if port 22 is blocked

If your network blocks SSH port 22, try using SSH over HTTPS port 443:

bash

# Test if port 443 works
ssh -T -p 443 [email protected]

# If successful, configure it permanently
nano ~/.ssh/config

# Add this section
Host github.com
    Hostname ssh.github.com
    Port 443
    User git

This works for GitHub and some other providers that offer SSH on port 443.

4Verify SSH key authentication

Ensure your SSH keys are properly configured and have correct permissions:

bash

# Check SSH directory permissions (should be 700)
ls -la ~/.ssh
chmod 700 ~/.ssh

# Check private key permissions (should be 600)
chmod 600 ~/.ssh/id_rsa
chmod 644 ~/.ssh/id_rsa.pub

# List your SSH keys
ls -la ~/.ssh/*.pub

# Display your public key to verify it matches what is on the server
cat ~/.ssh/id_rsa.pub

Verify the public key is added to your account on GitHub/GitLab/Bitbucket.

5Disable conflicting network connections

If you have multiple network interfaces active (both WiFi and Ethernet), disconnect one:

bash

# On Linux, list network interfaces
ip link show

# Temporarily disable WiFi if using Ethernet
sudo ip link set wlan0 down

# Or disable Ethernet if using WiFi
sudo ip link set eth0 down

On Windows/Mac, simply disable one network adapter in your network settings. SSH keys may be tied to specific MAC addresses, causing conflicts with multiple interfaces.

6Check and disable VPN if causing interference

VPNs can interfere with SSH connections. Try temporarily disabling your VPN:

bash

# Test connection without VPN
ssh -T [email protected]

# If it works, configure VPN split tunneling to exclude Git traffic
# Or switch to HTTPS for Git operations
git remote set-url origin https://github.com/username/repo.git

7Increase Git buffer size for large transfers

For large repositories, increase the HTTP post buffer to prevent connection drops:

bash

# Increase buffer to 500MB
git config --global http.postBuffer 524288000

# For slow connections, adjust timeout settings
git config --global http.lowSpeedLimit 0
git config --global http.lowSpeedTime 999999

This helps when the error occurs during push/pull of large files.

8Clear SSH known_hosts if experiencing host key issues

If DNS changes caused host key mismatches, clear the problematic entry:

bash

# Remove specific host from known_hosts
ssh-keygen -R github.com
ssh-keygen -R gitlab.com

# Or backup and clear entire known_hosts
mv ~/.ssh/known_hosts ~/.ssh/known_hosts.backup
touch ~/.ssh/known_hosts

The next connection will prompt you to accept the new host key.

9Switch to HTTPS if SSH issues persist

As a workaround, use HTTPS instead of SSH for Git operations:

bash

# Check current remote URL
git remote -v

# Change from SSH to HTTPS
git remote set-url origin https://github.com/username/repo.git

# For authentication, use a personal access token instead of password
git config --global credential.helper store

HTTPS is more firewall-friendly but requires token-based authentication.

How to fix kex_exchange_identification: Connection closed by remote host in Git

What this error means

Typical symptoms

Common causes

How to fix "kex_exchange_identification: Connection closed by remote host"

Advanced notes

Related errors

Official resources & further reading