Working with legacy CentOS 5.x systems (like the 2.6.18 kernel version mentioned) presents unique challenges when trying to update fundamental tools like cURL. The standard repositories often don't contain recent enough packages, forcing administrators to find alternative approaches.

For CentOS 5.x systems, you have several potential paths:

# Check current cURL version
curl --version

# View available packages
yum list curl --showduplicates

The most reliable method is to enable additional repositories that maintain newer packages for CentOS 5:

# Install EPEL repository (if not already present)
rpm -Uvh http://archive.fedoraproject.org/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm

# Search for available cURL packages
yum --enablerepo=epel search curl

When repositories don't have recent enough versions, you can download specific RPMs:

# Example for downloading and installing a newer cURL RPM
wget http://some-mirror.example.com/path/to/newer-curl.rpm
rpm -Uvh newer-curl.rpm --nodeps

Note: Be cautious about dependencies when using --nodeps

After installation, verify the new version is active:

# Check the upgraded version
curl --version

# Test HTTPS functionality
curl -I https://example.com

If you encounter SSL/TLS errors after upgrading:

# Check linked SSL library
ldd $(which curl) | grep ssl

# Potential fix for SSL issues
yum install openssl098e

For maximum version flexibility without affecting system packages:

# Download and extract a static binary
wget https://curl.se/download/curl-7.85.0.tar.gz
tar xzf curl-7.85.0.tar.gz
cd curl-7.85.0
./configure --disable-shared --enable-static
make
./src/curl --version

Working with an older CentOS system (like the 2.6.18 kernel mentioned) presents unique challenges when trying to get modern software versions. The default repositories often contain outdated packages - this is particularly true for cURL, which evolves rapidly with new features and security patches.

Before resorting to source compilation, try these repository approaches:

# Check available cURL versions in default repos
yum --showduplicates list curl

# Add EPEL repository (common first attempt)
sudo yum install epel-release
yum list available curl*

For CentOS 7/8 systems, the IUS community repository often provides newer packages while maintaining compatibility:

# CentOS 7 installation
sudo yum install https://repo.ius.io/ius-release-el7.rpm

# Check available versions
yum --disablerepo="*" --enablerepo="ius" list available curl*

# Install specific version
sudo yum install curl5

When repositories fail, consider downloading RPMs directly. For example, for CentOS 7:

wget https://mirror.city-fan.org/ftp/contrib/sysutils/Mirroring/curl-7.76.1-1.cf.rhel7.x86_64.rpm
sudo rpm -Uvh curl-7.76.1-1.cf.rhel7.x86_64.rpm

After installation, verify the new version works correctly:

curl --version
curl -V | head -n 1
curl --http2 https://example.com -I

Newer cURL versions often require updated dependencies. If you encounter errors, you might need:

sudo yum install libnghttp2 openssl-libs nghttp2

If all else fails, here's a quick source install guide:

wget https://curl.se/download/curl-7.79.1.tar.gz
tar -xzf curl-7.79.1.tar.gz
cd curl-7.79.1
./configure --with-nghttp2 --with-openssl
make
sudo make install

When upgrading system components like cURL:

• Always test in a staging environment first
• Document the changes made
• Consider creating a system restore point
• Monitor application dependencies that might rely on specific cURL versions