Not sure if this is known changed behavior in F24, but:
For the longest time I had /etc/sysconfig/network-scripts/eno2 specify:
TYPE=Ethernet BOOTPROTO=none DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=yes IPV6_AUTOCONF=yes IPV6_DEFROUTE=yes IPV6_FAILURE_FATAL=no NAME=wan0 UUID=71e6ac4b-c693-4c20-aa0d-e1a63b7373fe ONBOOT=yes IPADDR1=216.254.115.102 PREFIX1=24 IPADDR2=216.27.136.223 PREFIX2=24 HWADDR=0C:C4:7A:32:C1:83 IPADDR=216.254.115.190 GATEWAY=216.254.115.1 PREFIX=24 IPV6_PEERDNS=yes IPV6_PEERROUTES=yes
This host has three IP addresses, and up until now the default IP address for outgoing IP traffic was always 216.254.115.190, specified by IPADDR.
It appears that, right now, all of my outbound traffic now appears to come from one of the other IP addresses, 216.254.115.102.
This is true even if the outgoing socket explicitly binds to 216.254.115.190:
Sending mail to gmail, with an explicit bind(), strace shows:
13232 bind(5, {sa_family=AF_INET6, sin6_port=htons(0), inet_pton(AF_INET6, "::ffff:216.254.115.190", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 0 13232 fcntl(5, F_SETFL, O_RDONLY|O_NONBLOCK) = 0 13232 getsockopt(5, SOL_SOCKET, SO_TYPE, [1], [4]) = 0 13232 connect(5, {sa_family=AF_INET6, sin6_port=htons(25), inet_pton(AF_INET6, "::ffff:173.194.206.26", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = -1 EINPROGRESS (Operation now in progress) 13232 select(6, NULL, [5], NULL, {60, 0}) = 1 (out [5], left {59, 975901}) 13232 getsockopt(5, SOL_SOCKET, SO_ERROR, [0], [4]) = 0 13232 getsockname(5, {sa_family=AF_INET6, sin6_port=htons(41394), inet_pton(AF_INET6, "::ffff:216.254.115.190", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 0 13232 select(6, [5], [], NULL, {300, 0}) = 1 (in [5], left {299, 975360}) 13232 read(5, "220 mx.google.com ESMTP 92si8123707qkx.29 - gsmtp\r\n", 512) = 51
Gmail still shows 216.254.115.102 as the received-from IP address. I note that getsockname() insists that the socket is 216.254.115.190
This host is using masquerading, with firewalld. I suspect that this is firewalld's doing.
ip addr's output:
2: eno2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 link/ether 0c:c4:7a:32:c1:83 brd ff:ff:ff:ff:ff:ff inet 216.27.136.223/24 brd 216.27.136.255 scope global eno2 valid_lft forever preferred_lft forever inet 216.254.115.102/24 brd 216.254.115.255 scope global eno2 valid_lft forever preferred_lft forever inet 216.254.115.190/24 brd 216.254.115.255 scope global secondary eno2 valid_lft forever preferred_lft forever inet6 fe80::ec4:7aff:fe32:c183/64 scope link valid_lft forever preferred_lft forever
Anyone knows what could be the reason for this, I'd like to have 216.254.115.190 as the default externally-visible IP address.