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tests/vm: Set UseDNS=no in the sshd configuration

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make vm-build-freebsd sometimes fails with "Connection timed out during
banner exchange". The client strace shows:

    13:59:30 write(3, "SSH-2.0-OpenSSH_9.3\r\n", 21) = 21
    13:59:30 getpid()                       = 252655
    13:59:30 poll([{fd=3, events=POLLIN}], 1, 5000) = 1 ([{fd=3, revents=POLLIN}])
    13:59:32 read(3, "S", 1)                = 1
    13:59:32 poll([{fd=3, events=POLLIN}], 1, 3625) = 1 ([{fd=3, revents=POLLIN}])
    13:59:32 read(3, "S", 1)                = 1
    13:59:32 poll([{fd=3, events=POLLIN}], 1, 3625) = 1 ([{fd=3, revents=POLLIN}])
    13:59:32 read(3, "H", 1)                = 1

There is a 2s delay during connection, and ConnectTimeout is set to 1.
Raising it makes the issue go away, but we can do better. The server
truss shows:

    888: 27.811414714 socket(PF_INET,SOCK_DGRAM|SOCK_CLOEXEC,0) = 5 (0x5)
    888: 27.811765030 connect(5,{ AF_INET 10.0.2.3:53 },16) = 0 (0x0)
    888: 27.812166941 sendto(5,"\^Z/\^A\0\0\^A\0\0\0\0\0\0\^A2"...,39,0,NULL,0) = 39 (0x27)
    888: 29.363970743 poll({ 5/POLLRDNORM },1,5000) = 1 (0x1)

So the delay is due to a DNS query. Disable DNS queries in the server
config.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-ID: <20240206002344.12372-2-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This commit is contained in:
Ilya Leoshkevich 2024-02-06 01:22:00 +01:00 committed by Thomas Huth
parent d0143fa9ee
commit 7f0bf5ea41
1 changed files with 2 additions and 0 deletions
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2
tests/vm/basevm.py
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@ -423,6 +423,8 @@ class BaseVM(object):
def console_sshd_config(self, prompt): def console_sshd_config(self, prompt):
self.console_wait(prompt) self.console_wait(prompt)
self.console_send("echo 'PermitRootLogin yes' >> /etc/ssh/sshd_config\n") self.console_send("echo 'PermitRootLogin yes' >> /etc/ssh/sshd_config\n")
self.console_wait(prompt)
self.console_send("echo 'UseDNS no' >> /etc/ssh/sshd_config\n")
for var in self.envvars: for var in self.envvars:
self.console_wait(prompt) self.console_wait(prompt)
self.console_send("echo 'AcceptEnv %s' >> /etc/ssh/sshd_config\n" % var) self.console_send("echo 'AcceptEnv %s' >> /etc/ssh/sshd_config\n" % var)