CentOS系统中Apache服务无法启动/重启的问题排查与解决请求

问题情况 #

之前运行正常的Apache突然无法重启，执行apachectl configtest返回符号查找错误：

/usr/local/apache/bin/httpd: undefined symbol: apr_crypto_init

systemctl status httpd.service输出如下：

httpd.service - Web server Apache
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Tue 2022-10-04 22:36:27 CST; 1min 24s ago
  Process: 13030 ExecStop=/usr/local/apache/bin/apachectl graceful-stop (code=exited, status=127)
  Process: 3911 ExecStart=/usr/local/apache/bin/apachectl start (code=exited, status=127)
 Main PID: 851 (code=exited, status=0/SUCCESS)

Oct 04 22:36:27 hwsrv-985893.hostwindsdns.com systemd[1]: Starting Web server Apache...
Oct 04 22:36:27 hwsrv-985893.hostwindsdns.com apachectl[3911]: /usr/local/apache/bin/httpd: symbol lookup error: /usr/local/apache/bin/httpd: undefined symbol: apr_crypto_init
Oct 04 22:36:27 hwsrv-985893.hostwindsdns.com systemd[1]: httpd.service: control process exited, code=exited status=127
Oct 04 22:36:27 hwsrv-985893.hostwindsdns.com systemd[1]: Failed to start Web server Apache.
Oct 04 22:36:27 hwsrv-985893.hostwindsdns.com systemd[1]: Unit httpd.service entered failed state.
Oct 04 22:36:27 hwsrv-985893.hostwindsdns.com systemd[1]: httpd.service failed.

journalctl -xe输出未包含Apache启动失败的相关有效信息，仅显示SSH暴力破解日志：

Oct 04 22:51:54 hwsrv-985893.hostwindsdns.com kernel: net_ratelimit: 75 callbacks suppressed
Oct 04 22:51:56 hwsrv-985893.hostwindsdns.com sshd[4063]: Failed password for root from 61.177.172.114 port 36803 ssh2
Oct 04 22:51:56 hwsrv-985893.hostwindsdns.com sshd[4065]: Failed password for root from 218.92.0.195 port 33236 ssh2
Oct 04 22:51:56 hwsrv-985893.hostwindsdns.com sshd[4063]: Received disconnect from 61.177.172.114 port 36803:11:  [preauth]
Oct 04 22:51:56 hwsrv-985893.hostwindsdns.com sshd[4063]: Disconnected from 61.177.172.114 port 36803 [preauth]
Oct 04 22:51:56 hwsrv-985893.hostwindsdns.com sshd[4063]: PAM 2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=61.177.172.114  user=root
Oct 04 22:51:56 hwsrv-985893.hostwindsdns.com sshd[4065]: pam_succeed_if(sshd:auth): requirement "uid >= 1000" not met by user "root"
Oct 04 22:51:59 hwsrv-985893.hostwindsdns.com sshd[4065]: Failed password for root from 218.92.0.195 port 33236 ssh2
Oct 04 22:51:59 hwsrv-985893.hostwindsdns.com sshd[4065]: Received disconnect from 218.92.0.195 port 33236:11:  [preauth]
Oct 04 22:51:59 hwsrv-985893.hostwindsdns.com sshd[4065]: Disconnected from 218.92.0.195 port 33236 [preauth]
Oct 04 22:51:59 hwsrv-985893.hostwindsdns.com sshd[4065]: PAM 2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=218.92.0.195  user=root
Oct 04 22:51:59 hwsrv-985893.hostwindsdns.com kernel: net_ratelimit: 65 callbacks suppressed
Oct 04 22:52:05 hwsrv-985893.hostwindsdns.com kernel: net_ratelimit: 77 callbacks suppressed

问题根源 #

报错undefined symbol: apr_crypto_init本质是httpd无法找到APR（Apache运行时库）加密模块的初始化函数，常见原因包括：

• APR/APR-util版本不兼容：近期更新过APR库，但httpd基于旧版APR编译，导致符号匹配失败
• 加密库丢失或损坏：APR加密相关库（如libaprutil-1.so）被误删、损坏，或系统无法识别库路径
• httpd编译配置问题：编译时启用了加密支持，但运行环境缺少对应库依赖

解决办法 #

办法1：检查并修复APR库依赖 #

1. 查找系统中APR-util库的位置：

find / -name "libaprutil-1.so*"

2. 验证httpd是否能识别该库：

ldd /usr/local/apache/bin/httpd | grep aprutil

若未找到库路径，需添加到动态链接配置：

• 编辑/etc/ld.so.conf.d/apr.conf，写入库所在路径（例如/usr/local/apr/lib）
• 执行ldconfig更新缓存

办法2：重新编译APR与httpd（源码编译环境适用） #

1. 卸载现有不兼容的APR/APR-util：

# 源码安装环境，进入APR源码目录执行
make uninstall
# 包管理器环境（以CentOS为例）
yum remove apr apr-util

2. 下载并编译匹配版本的APR和APR-util：

# 下载APR（版本需与httpd编译时一致，示例版本）
wget https://dlcdn.apache.org/apr/apr-1.7.4.tar.gz
tar zxvf apr-1.7.4.tar.gz
cd apr-1.7.4
./configure --prefix=/usr/local/apr
make && make install

# 下载APR-util
wget https://dlcdn.apache.org/apr/apr-util-1.6.3.tar.gz
tar zxvf apr-util-1.6.3.tar.gz
cd apr-util-1.6.3
./configure --prefix=/usr/local/apr-util --with-apr=/usr/local/apr
make && make install

3. 重新编译httpd并指定APR路径：

cd httpd源码目录
./configure --prefix=/usr/local/apache --with-apr=/usr/local/apr --with-apr-util=/usr/local/apr-util
make && make install

办法3：回滚APR版本（近期更新过APR时适用） #

若更新APR后出现问题，直接回滚至之前正常版本：

• 包管理器环境（CentOS）：

yum downgrade apr apr-util

• 源码安装环境：重新编译旧版本APR并安装

办法4：检查httpd编译配置 #

确认编译时是否启用加密支持，若需要则重新编译时添加--enable-crypto选项：

./configure --prefix=/usr/local/apache --with-apr=/usr/local/apr --with-apr-util=/usr/local/apr-util --enable-crypto

验证修复 #

执行apachectl configtest，若返回Syntax OK则重启httpd：

systemctl restart httpd.service

再通过systemctl status httpd.service确认服务状态正常。

内容的提问来源于stack exchange，提问作者johnoula