Many developers working behind corporate firewalls encounter this puzzling scenario:

fatal: Unable to look up someserver.org (port 9418) (No such host is known.)

While your browser happily loads the same domain, command-line tools like ping and git fail to resolve hostnames. This typically indicates a split DNS configuration or firewall restrictions on your corporate network.

First, let's verify the symptoms with these commands:

# Check basic DNS resolution
nslookup someserver.org
ping someserver.org

# Test git specifically
git ls-remote git://someserver.org/repo.git

If these fail while browser access works, we're dealing with one of these scenarios:

• Corporate proxy intercepting HTTP/HTTPS but not other protocols
• Firewall blocking non-web ports (like git's 9418)
• Different DNS servers for different applications

1. Using SSH Instead of Git Protocol

Many corporate networks allow SSH (port 22) while blocking git:// (port 9418):

git clone ssh://git@someserver.org:repo.git
# Or for GitHub-like services:
git clone git@github.com:user/repo.git

2. Configuring Git to Use HTTPS

Force git to use the web protocol which bypasses the restriction:

git config --global url."https://".insteadOf git://
git config --global url."https://github.com/".insteadOf git@github.com:

3. Custom DNS Resolution

If DNS is the issue, try overriding system DNS:

# Linux/macOS
sudo vim /etc/resolv.conf
# Add: nameserver 8.8.8.8

# Windows (Admin PowerShell)
Set-DnsClientServerAddress -InterfaceIndex 12 -ServerAddresses 8.8.8.8,8.8.4.4

4. Proxy Configuration for Git

If your company uses a web proxy:

git config --global http.proxy http://proxy.example.com:8080
git config --global https.proxy https://proxy.example.com:8080

For strict networks, create an SSH tunnel to an external server:

ssh -L 9418:someserver.org:9418 user@external-server.com
# Then locally:
git clone git://localhost/repo.git

These commands help identify network issues:

# Check DNS resolution
dig someserver.org
host someserver.org

# Check port accessibility
telnet someserver.org 9418
nc -zv someserver.org 9418

# Trace network path
traceroute someserver.org
pathping someserver.org

Remember that corporate IT policies exist for security reasons. Always check with your network administrators before implementing workarounds.

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When working behind corporate networks, you might encounter a situation where your browser can access a Git server (like GitHub or Bitbucket) while command-line tools fail with errors like:

fatal: Unable to look up someserver.org (port 9418) (No such host is known.)

This typically indicates DNS resolution issues specific to non-browser applications.

First, let's verify the symptoms:

# Basic connectivity tests
ping someserver.org          # Fails
nslookup someserver.org      # Fails
curl https://someserver.org  # Works in browser but fails in CLI

This behavior usually stems from:

• HTTP proxy configurations affecting only browser traffic
• Split DNS configurations where internal/external lookups differ
• Firewall rules blocking non-web ports (like Git's 9418)
• Different DNS servers being used by browser vs system

Solution 1: Configure Git to Use HTTPS Instead of SSH

git config --global url."https://".insteadOf git://
git config --global url."https://github.com/".insteadOf git@github.com:

Solution 2: Override DNS Resolution

Find the IP address through your browser (using developer tools) and add it to your hosts file:

# Linux/Mac
echo "123.45.67.89 someserver.org" | sudo tee -a /etc/hosts

# Windows (Run as Administrator)
Add-Content -Path $env:windir\System32\drivers\etc\hosts -Value "123.45.67.89 someserver.org"

Solution 3: Configure System-Wide Proxy

# Linux
export http_proxy=http://corporate.proxy:8080
export https_proxy=http://corporate.proxy:8080

# Windows
netsh winhttp set proxy corporate.proxy:8080

Solution 4: Use SSH Config Bypass

# ~/.ssh/config
Host github.com
    Hostname ssh.github.com
    Port 443
    User git

After applying any solution, test with:

git ls-remote https://someserver.org/repo.git
# or
ssh -T git@someserver.org