dhclient 卡死
学习 openstack 和 openvswitch 过程中， 遇到dhclient 卡死，而且也分配不了地址，于是只能先学习 dhcp 服务器和 dhclient。搭建的一个假的网关 （203.0.113.1），之前是 2 个网卡，现在增加一个eth2 ，用于直接在本机先测试。其实，最简单还是 journalctl -xe ，也看到了 问题出在 n1.local.tecadmin.ne。所以，他
问题
学习 openstack 和 openvswitch 过程中， 遇到dhclient 卡死，而且也分配不了地址，于是只能先学习 dhcp 服务器和 dhclient
还使用之前 Ubuntu 20.04 手动安装OpenStack 搭建的一个假的网关 （203.0.113.1），之前是 2 个网卡，现在增加一个eth2 ，用于直接在本机先测试
环境
Ubuntu 20.04 虚拟机
eth0 ： 192.168.0.109 （用于远程管理）
eth1 ： 203.0.113.1 （网关）
eth2 ： 用于dhclient 测试
搭建DHCP 服务器
这是服务端安装
Dynamic Host Configuration Protocol (DHCP)
这是网卡配置 （客户端）
Network Configuration
抄录并整理一下步骤
-
sudo apt install isc-dhcp-server
-
修改配置
root@gate-109:/etc/dhcp# vim /etc/dhcp/dhcpd.conf
...... # wzh 20221212 subnet 203.0.113.0 netmask 255.255.255.0 { range 203.0.113.10 203.0.113.100; option routers 203.0.113.1; option subnet-mask 255.255.255.0; # option domain-search "local.tecadmin.net"; # option domain-name-servers n1.local.tecadmin.net; option domain-search ""; option domain-name-servers 203.0.113.1; option time-offset -18000; option broadcast-address 203.0.113.255; default-lease-time 600; max-lease-time 7200; } ......卡死的原因在于 ： local.tecadmin.net 找不到！
后面错误处理再叙述 -
dhcp 服务网卡指定 （ubuntu 文档中没有）
root@gate-109:/etc/netplan# vim /etc/default/isc-dhcp-server
修改最后两行# wzh 20221212 INTERFACESv4="eth1" INTERFACESv6="eth1" -
重启生效
sudo systemctl restart isc-dhcp-server.service -
确认
root@gate-109:/etc/netplan# netstat -tulnp | grep dhcpudp 0 0 0.0.0.0:67 0.0.0.0:* 818/dhcpd
dhclient 客户端
-
最终效果
root@gate-109:/etc/dhcp# ip addr show eth24: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 link/ether 00:15:5d:5a:a6:95 brd ff:ff:ff:ff:ff:ff inet 203.0.113.12/24 brd 203.0.113.255 scope global dynamic eth2 valid_lft 308sec preferred_lft 308sec inet6 fe80::215:5dff:fe5a:a695/64 scope link valid_lft forever preferred_lft forever -
不管 dhclient 是否卡死，好像一直在执行
root@gate-109:/etc/dhcp# ps -ef |grep dhc
dhcpd 818 1 0 09:12 ? 00:00:00 dhcpd -user dhcpd -group dhcpd -f -4 -pf /run/dhcp-server/dhcpd.pid -cf /etc/dhcp/dhcpd.conf eth1 root 1662 1 0 10:21 ? 00:00:00 dhclient eth2 root 1823 1 0 10:43 ? 00:00:00 dhclient eth2 root 1850 1 0 10:43 ? 00:00:00 dhclient eth2 root 1885 1499 0 10:47 pts/1 00:00:00 grep --color=auto dhc -
执行到 3 次以后，就不再分配了，继续执行就会这样
root@gate-109:/etc/netplan# dhclient eth2RTNETLINK answers: File exists所以，他从 203.0.113.10/24 开始，执行了 3 次，就变成 203.0.113.12/24
错误处理
-
Not configured to listen on any interfaces!
root@ubuntu2004-121:/home/dhbm# systemctl status isc-dhcp-server
● isc-dhcp-server.service - ISC DHCP IPv4 server Loaded: loaded (/lib/systemd/system/isc-dhcp-server.service; enabled; vendor preset: enabled) Active: failed (Result: exit-code) since Mon 2022-12-12 14:12:25 CST; 2min 20s ago Docs: man:dhcpd(8) Process: 26013 ExecStart=/bin/sh -ec CONFIG_FILE=/etc/dhcp/dhcpd.conf; if [ -f /etc/ltsp/dhcpd.conf ]; then CONFIG_FILE=/etc/ltsp/dhcpd.conf; fi; [ -e /var/lib/dhcp/dhcpd.leases ] ||> Main PID: 26013 (code=exited, status=1/FAILURE) Dec 12 14:12:25 gate-109 dhcpd[26013]: Dec 12 14:12:25 gate-109 dhcpd[26013]: Not configured to listen on any interfaces! Dec 12 14:12:25 gate-109 dhcpd[26013]: Dec 12 14:12:25 gate-109 dhcpd[26013]: If you think you have received this message due to a bug rather Dec 12 14:12:25 gate-109 dhcpd[26013]: than a configuration issue please read the section on submitting Dec 12 14:12:25 gate-109 dhcpd[26013]: bugs on either our web page at www.isc.org or in the README file Dec 12 14:12:25 gate-109 dhcpd[26013]: before submitting a bug. These pages explain the proper Dec 12 14:12:25 gate-109 dhcpd[26013]: process and the information we find helpful for debugging. Dec 12 14:12:25 gate-109 dhcpd[26013]: Dec 12 14:12:25 gate-109 dhcpd[26013]: exiting. ......处理：
记不太清楚了！大概是修改正确的 IP 地址网段，开始时我好像是设置的 10.0.0.0/24 ，但是 DHCP 服务在 203.0.113.0/24 -
Not configured to listen on any interfaces!
root@ubuntu2004-121:/home/dhbm# systemctl status isc-dhcp-server
Dec 12 14:12:25 gate-109 dhcpd[26027]: Dec 12 14:12:25 gate-109 dhcpd[26027]: Not configured to listen on any interfaces! Dec 12 14:12:25 gate-109 dhcpd[26027]: Dec 12 14:12:25 gate-109 dhcpd[26027]: If you think you have received this message due to a bug rather Dec 12 14:12:25 gate-109 dhcpd[26027]: than a configuration issue please read the section on submitting Dec 12 14:12:25 gate-109 dhcpd[26027]: bugs on either our web page at www.isc.org or in the README file Dec 12 14:12:25 gate-109 dhcpd[26027]: before submitting a bug. These pages explain the proper Dec 12 14:12:25 gate-109 dhcpd[26027]: process and the information we find helpful for debugging. Dec 12 14:12:25 gate-109 dhcpd[26027]: Dec 12 14:12:25 gate-109 dhcpd[26027]: exiting.处理：
dhcp 服务网卡指定root@gate-109:/etc/netplan# vim /etc/default/isc-dhcp-server
修改最后两行# wzh 20221212 INTERFACESv4="eth1" INTERFACESv6="eth1" -
dhclient 卡死
开始时总想找到 dhclient 的 error 日志，所以就 greproot@gate-109:/var/log# grep -nr dhc * root@gate-109:/var/log# grep -nr "n1.local.tecadmin.net" *也找到了问题出在 n1.local.tecadmin.ne
其实，最简单还是 journalctl -xe ，也看到了 问题出在 n1.local.tecadmin.ne
root@gate-109:/var/log# journalctl -xe
…Dec 13 09:32:47 gate-109 dhcpd[818]: DHCPREQUEST for 203.0.113.10 from 00:15:5d:5a:a6:91 (ubuntu2004-101) via eth1 Dec 13 09:32:48 gate-109 systemd-resolved[721]: Using degraded feature set (UDP) for DNS server 223.5.5.5. Dec 13 09:32:52 gate-109 systemd-resolved[721]: Using degraded feature set (TCP) for DNS server 114.114.114.114. Dec 13 09:32:55 gate-109 systemd-resolved[721]: Using degraded feature set (TCP) for DNS server 223.5.5.5. Dec 13 09:32:57 gate-109 dhcpd[818]: n1.local.tecadmin.net: temporary name server failure Dec 13 09:32:57 gate-109 dhcpd[818]: DHCPACK on 203.0.113.10 to 00:15:5d:5a:a6:91 (ubuntu2004-101) via eth1 Dec 13 09:33:01 gate-109 systemd-resolved[721]: Using degraded feature set (TCP) for DNS server 114.114.114.114. Dec 13 09:33:04 gate-109 systemd-resolved[721]: Using degraded feature set (UDP) for DNS server 114.114.114.114. Dec 13 09:33:04 gate-109 systemd-resolved[721]: Using degraded feature set (UDP) for DNS server 223.5.5.5. Dec 13 09:33:07 gate-109 systemd-resolved[721]: Using degraded feature set (TCP) for DNS server 223.5.5.5. Dec 13 09:33:10 gate-109 systemd-resolved[721]: Using degraded feature set (UDP) for DNS server 114.114.114.114. Dec 13 09:33:19 gate-109 systemd-resolved[721]: Using degraded feature set (TCP) for DNS server 223.5.5.5. Dec 13 09:33:22 gate-109 systemd-resolved[721]: Using degraded feature set (TCP) for DNS server 114.114.114.114. Dec 13 09:33:25 gate-109 systemd-resolved[721]: Using degraded feature set (UDP) for DNS server 223.5.5.5. Dec 13 09:33:28 gate-109 systemd-resolved[721]: Using degraded feature set (TCP) for DNS server 114.114.114.114. Dec 13 09:33:38 gate-109 systemd-resolved[721]: Using degraded feature set (UDP) for DNS server 223.5.5.5. Dec 13 09:33:41 gate-109 systemd-resolved[721]: Using degraded feature set (UDP) for DNS server 114.114.114.114. Dec 13 09:33:44 gate-109 systemd-resolved[721]: Using degraded feature set (TCP) for DNS server 223.5.5.5. Dec 13 09:33:47 gate-109 systemd-resolved[721]: Using degraded feature set (UDP) for DNS server 114.114.114.114.
分析 ：
过去配置静态 ip 时，最后总是 search: [],从来没有想过为什么
既然 search: [] 可以，那么干脆配置文件中也空，不用 n1.local.tecadmin.net
处理：
修改配置
root@gate-109:/etc/dhcp# vim /etc/dhcp/dhcpd.conf
......
# wzh 20221212
subnet 203.0.113.0 netmask 255.255.255.0 {
range 203.0.113.10 203.0.113.100;
option routers 203.0.0.1;
option subnet-mask 255.255.255.0;
# option domain-search "local.tecadmin.net";
# option domain-name-servers n1.local.tecadmin.net;
option domain-search "";
option domain-name-servers 203.0.113.1;
option time-offset -18000;
option broadcast-address 203.0.113.255;
default-lease-time 600;
max-lease-time 7200;
}
......
再来 dhclient eth2 ，立马 OK ！哈哈哈哈！
后续
以上使用了第三块卡 eth2 ，并且在本机进行
如果在其他服务器呢？
如果是虚拟机呢？
待继续…
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