My server has 5 different external IPs (all working)
I added them by using:
ip addr add xx.xx.xx.xx/32 dev eth0
ip addr add yy.yy.yy.yy/32 dev eth0
ip addr add zz.zz.zz.zz/32 dev eth0
How can I should curl to use either zz.zz.zz.zz IP address ?
You should be able to use
curl --interface zz.zz.zz.zz http://example.com/
Related
I am attempting to validate ECMP functionality on a linux host with unnumbered interfaces and network namespaces.
The following example can be used to demonstrate:
# add address to loopback for unnumbered veth interfaces
ip addr add 198.51.100.0/32 dev lo
# namespace 1
ip netns add ns1
ip link add veth100 type veth peer name veth101
ip link set veth100 up
ip link set veth101 netns ns1
ip netns exec ns1 ip link set veth101 name eth0
ip netns exec ns1 ip addr add 192.0.2.1/32 dev eth0
ip netns exec ns1 ip link set eth0 up
ip netns exec ns1 ip route add 198.51.100.0/32 dev eth0
ip netns exec ns1 ip route add 0.0.0.0/0 via 198.51.100.0
ip route add 192.0.2.1/32 dev veth100
# namespace 2
ip netns add ns2
ip link add veth200 type veth peer name veth201
ip link set veth200 up
ip link set veth201 netns ns2
ip netns exec ns2 ip link set veth201 name eth0
ip netns exec ns2 ip addr add 192.0.2.2/32 dev eth0
ip netns exec ns2 ip link set eth0 up
ip netns exec ns2 ip route add 198.51.100.0/32 dev eth0
ip netns exec ns2 ip route add 203.0.113.0/32 dev eth0
ip netns exec ns2 ip route add 0.0.0.0/0 via 198.51.100.0
ip route add 192.0.2.2/32 dev veth200
# anycast / ecmp setup
ip netns exec ns1 ip addr add 203.0.113.0/32 dev lo
ip netns exec ns1 ip link set dev lo up
ip netns exec ns2 ip addr add 203.0.113.0/32 dev lo
ip netns exec ns2 ip link set dev lo up
ip route append 203.0.113.0/32 nexthop via 192.0.2.1 weight 100
ip route append 203.0.113.0/32 nexthop via 192.0.2.2 weight 100
I can see that I have two routes in my routing table:
$ ip route show
...
203.0.113.0 via 192.0.2.1 dev veth100 onlink
203.0.113.0 via 192.0.2.2 dev veth200 onlink
...
Ping to 203.0.113.0 works (as expected):
$ ping 203.0.113.0 -c 2
PING 203.0.113.0 (203.0.113.0) 56(84) bytes of data.
64 bytes from 203.0.113.0: icmp_seq=1 ttl=64 time=0.096 ms
64 bytes from 203.0.113.0: icmp_seq=2 ttl=64 time=0.079 ms
--- 203.0.113.0 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1024ms
rtt min/avg/max/mdev = 0.079/0.087/0.096/0.008 ms
I can set either veth100 or veth200 down and achieve fail over. However, the load does not appear to be shared across veth100 and veth200 at the same time. I verified this by tcpdump'ing both veth100 and veth200 at the same time.
Experimenting, I've tried adding the ecmp route this way:
ip route add 203.0.113.0/32 nexthop via 192.0.2.2 weight 10 nexthop via 192.0.2.1 weight 10
The route appears to be installed differently. I'm not sure what the difference is in reality, but it looks different.
$ ip route show
...
203.0.113.0
nexthop via 192.0.2.2 dev veth200 weight 10
nexthop via 192.0.2.1 dev veth100 weight 10
...
But, this still has the same problem as mentioned above.
I'm not sure what next steps to take. What am I doing wrong? Is there any way to achieve ECMP load sharing in this scenario?
If you're only testing with ICMP pings the behaviour is expected. ECMP's 5-tuple hash (sourceIP+sourcePort+destIP+destPort+protocol) can't work with ICMP since it doesn't use port numbers so you'll always hit the same host.
Experiment with multiple UDP and TCP and you should see the load balancing effect since at least source ports should be ephemeral (unlike the destination well-known service ports).
BTW - thanks for spelling out the steps you took since I'm currently experimenting with the same concepts in order to replace the K8S network mess with simple load-balanced, routed, IPv6 only.
The issus is:
I configured the following policy routing：
ip route add 192.168.1.0/24 via 10.0.2.15 dev eth0 table 10
ip route add default via 10.0.2.15 dev eth0 table 10
ip rule add from 10.0.2.15 table 10
these configurations are temporary, once network restart or reboot,the policy route I configured would lost, Is there any way you can solve this problem？
Create a file if does not exist
/etc/sysconfig/network-scripts/route-eth0
Add the following contents
192.168.1.0/24 via 10.0.2.15 dev eth0
default via 10.0.2.15 dev eth0
default route can be added in /etc/sysconfig/network-scripts/ifcfg-eth0
GATEWAY=10.0.2.15
Third rule is not clear to me
In my Linux server I have 2 interfaces so the linux server can be accessed via Terminal by typing
ssh username#IP1
or ssh username#IP2
Every thing works fine until I restarted my server. Now I could only access the linux server via the first IP address.
I checked IP configuration (here I am connected to the server via my first IP address)nano etc/network/interfacesgives:
iface eth0 inet static
address 192.168.1.13
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.253
# dns-* options are implemented by the resolvconf package, if installed
dns-nameservers 192.168.1.2
# The secondary network interface
allow-hotplug eth1
iface eth1 inet static
address 192.168.1.14
netmask 255.255.255.255
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.253
dns-nameservers 192.168.2.2
ifconfig shows that only eth0 is up so, so once I typed nano /sys/class/net/eth1/operstateI discovered that this interface(second IP adress) is down so I tried ifconfig eth1 192.168.1.14 netmask 255.255.255.255 up and then restarted my networking service and ifconfig shows that my interface is up and can be accessed via terminal, but my access is denied (Permission denied, please try again) once I tried ssh username#192.168.1.14what can I
do in order to be able to access the servers via terminal with this IP address
Try to ping the second interface just to make sure there isn't something wrong with the network itself
Make sure that SSH Daemon is configured to listen on both ports.
i'm pretty sure that the problem is in this line:
allow-hotplug eth1
change it to auto eth1, the interface should now start whenever the system starts.
I am creating GRE Tunnel between two Linux (CentOS6) servers using below steps.
On the master server:
chkconfig iptables off
service iptables stop
sysctl -w net.ipv4.conf.default.rp_filter=0
modprobe ip_gre
ip tunnel add tun1 mode gre remote 98.123.87.97 local 106.61.58.98 ttl 255
ip addr add 10.0.1.0/24 dev tun1
ip link set dev tun1 up
ip addr add 98.123.87.95/27 dev eth0
On the slave server:
chkconfig iptables off
service iptables stop
sysctl -w net.ipv4.ip_forward=1
sysctl -w net.ipv4.conf.all.forwarding=1
sysctl -w net.ipv4.conf.proxy_arp=1
sysctl -w net.ipv4.conf.all.proxy_arp=1
sysctl -w net.ipv4.conf.eth0.rp_filter=0
sysctl -w net.ipv4.conf.default.rp_filter=0
modprobe ip_gre
ip tunnel add tunx mode gre remote 106.61.58.98 local 98.123.87.97 ttl 255
ip addr add 10.0.2.0/24 dev tun0
ip link set tunx up
ip route add 98.123.87.95/27 dev tun0
I need to add slave server's IP into the on my master server, I am getting the ping response form tunnelled IPs (Slave Server's IP) and when I am trying to SSH the tunnelled IP (Slave IP) I am reaching to Masters(this is what I want).
Problem is when I am trying to send outgoing traffic like DNS query by Tunnelled IP(Slave IP) I am getting time out request.
I guess this is routing issue of one of my server. Any idea what should i do to get through my outgoing traffic by tunnelled IPs?
Thanks,
Are you really adding 10.0.1.0/24 address? This is a network address, looks like mistake.
Also, you shuold add default route(or route to dns servers or whatever you want) on client machine through your tunnel with gateway=another_end_of_tunnel.
Don't forget to add static route to your machine if you don't want to loose connection, before adding default route!
I have configured my server with static ip address but when happens a certain time change the ip address and I have to restart the network to put the original ip address.
This is my configuration:
auto eth0
iface eth0 inet static
address 192.168.1.218
netmask 255.255.255.0
gateway 192.168.1.100
nameserver 192.168.1.210
thank's